1. Lecture08: Static Variable, Memory Model, Top-Down Program Development 4/22/2013

2. Outline Midterm results Static variables Memory model
Program development
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

3. Midterm results Good job – most of you have done well. Avg: 84.68
Std: 36
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

4. Static Local Variables A permanent variable inside a function whose value lifetime lasts through the entire program execution (vs. local variable, its storage is gone at the end of the function)
#include <stdio.h> void f1() { static int k=0; int j = 10; printf("value of k=%d j=%d\n", k, j); k=k+10; } void main() int i = 0; f1(); printf("after first call\n"); printf("after second call\n"); printf("after third call\n");
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

5. Exercise 8-1
Complete the following function sumit() that reads an integer from the user, computes an accumulative sum, and print it out.
void sumit() {
static int sum = 0;
..int num;
printf("\nEnter a number: ");
..scanf("%d", &num);
..sum+=num;
printf("The current sum is: %d", sum); }
int main()
int i =0;
printf("Enter 5 numbers to be summed\n");
for(i = 0; i<5; ++i)
sumit();
printf("Program completed\n");
return 0;
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

6. C Memory Model – where are variables & program code stored in the computer memory?
Function variables
Arguments
Local variables
Return location
Global Variables
Statically allocated
Dynamically allocated
int fact (int n)
{ return(n*fact(n-1)); }
void main() { … fact(5); …}
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

7. The Stack Stores Function local variables Temporary variables
Arguments for next function call
Where to return when function ends
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

8. The Stack Managed by compiler
One stack frame each time function called
Created when function called
Stacked on top (under) one another
Destroyed at function exit
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

9. What can go wrong? Recall that local variables are stored on the stack
Memory for local variables is deallocated when function returns
Returning a pointer to a local variable is almost always a bug!
char *my_strcat(char *s1, char *s2) {
char s3[1024];
strcpy(s3, s1);
strcat(s3, s2);
return s3; }
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

10. What Can Go Wrong? Run out of stack space
Unintentionally change values on the stack
In some other function's frame
Even return address from function
Access memory even after frame is deallocated
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

11. The Heap C can use space in another part of memory: the heap
The heap is separate from the execution stack
Heap regions are not deallocated when a function returns
The programmer requests storage space on the heap
C never puts variables on the heap automatically
But local variables might point to locations on the heap
Heap space must be explicitly allocated and deallocated by the programmer
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

12. malloc() Library function in <stdlib.h>
Stands for memory allocate
Requests a memory region of a specied size
Syntax: void *malloc(int size)
void * is generic pointer type
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

13. Usage Good to check the return value from malloc()
int main() { int* p1 = (int *) malloc(10 * sizeof(int)); if (p1 == NULL) // do cleanup } // do something free(p1); return 0;
Good to check the return value from malloc()
Must explicitly free memory when no longer in use
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

14. What Can Go Wrong? Run out of heap space: malloc returns 0
Unintentionally change other heap data
Access memory after free'd
free memory twice
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

15. Multidimensional Array
On the stack: int a[10][20];
Initialization: int a[][] = {{1, 2, 3}, {4, 5, 6}};
Accessing the array: a[1][0]
On the heap: int **a = (int **) malloc()
The array size is not known until runtime and stored in a variable x
int **a = (int **) malloc(x * sizeof(int *));
for (int i = 0; i < 10; i++) {
a[i] = (int *) malloc(20 * sizeof(int)); }
Don't forget to free them!
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

16. Exercise 8-2
Write a program that (1) asks for the number of friends, (2) asks for a name, and (3) checks a series of strings to see which one matches the names of friends. Please use
Use malloc() to create this multi-dimensional array to stores friends’ names. Assume that each name is less than 10 characters.
Use <string.h> library
Use scanf(“ %s”, ..) to read a name separated by one or more whitespaces
You can modify from the skeleton code on the next slide.
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

17. #include <stdio. h> #include <string. h> int main() { char
#include <stdio.h> #include <string.h> int main() { char** friends; char name[10]; int n, i; printf("Input the number of your friends: "); scanf("%d", &n); /* call malloc() to allocate dynamic memory for friends and friends[1..n-1] */ … for (;;) printf("Input a name: "); scanf(" %s", name); for (i=0; i<n; i++) if (strcmp(friends[i], name) == 0) printf("%s is friend #%d\n", name, i+1); break; } if (i == n) printf("%s is not a friend\n", name); /* call free() to free memory for friends and friends[1..n-1] */
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

18. Program development (important!)
A Common problem
Know all C commands but don’t know how to use them to write a program.
Top-down approach – always work!
Start by writing down the main steps (in words/comments, not code) of a program. Like a paragraph in an essay.
For each difficult main step, break it down into smaller steps. Again in words/comments, not code.
Apply this “divide-and-conquer” approach until the steps are simple enough to code.
Write code
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

19. Last Year’s Midterm Problem 1
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

20. Top-Down Approach to Program Development
Start by writing down the main steps (in words/comments, not code) of a program. Like a paragraph in an essay.
For each difficult main step, break it down into smaller steps. Again in words/comments, not code.
Apply this “divide-and-conquer” approach until the steps are simple enough to code.
Write code
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

21. Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

22. Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

23. Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

24. Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

25. Top-Down Approach to Program Development
Start by writing down the main steps (in words/comments, not code) of a program. Like a paragraph in an essay.
For each difficult main step, break it down into smaller steps. Again in words/comments, not code.
Apply this “divide-and-conquer” approach until the steps are simple enough to code.
Write code
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

26. Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

27. Top-Down Approach to Program Development
Start by writing down the main steps (in words/comments, not code) of a program. Like a paragraph in an essay.
For each difficult main step, break it down into smaller steps. Again in words/comments, not code.
Apply this “divide-and-conquer” approach until the steps are simple enough to code.
Write code
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

28. Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

29. Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

30. Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

31. Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

32. Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

33. Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

34. Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

35. Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

36. Systematic way of writing programs
Like writing an essay.
Start with an outline that describes what you are going to write.
Okay to write the comments in Chinese.
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

37. Exercise 8-3
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

38. Top-Down Approach to Program Development
Start by writing down the main steps (in words/comments, not code) of a program. Like a paragraph in an essay.
For each difficult main step, break it down into smaller steps. Again in words/comments, not code.
Apply this “divide-and-conquer” approach until the steps are simple enough to code.
Write code
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

39. Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

40. Top-Down Approach to Program Development
Start by writing down the main steps (in words/comments, not code) of a program. Like a paragraph in an essay.
For each difficult main step, break it down into smaller steps. Again in words/comments, not code.
Apply this “divide-and-conquer” approach until the steps are simple enough to code.
Write code
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

41. Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

42. Top-Down Approach to Program Development
Start by writing down the main steps (in words/comments, not code) of a program. Like a paragraph in an essay.
For each difficult main step, break it down into smaller steps. Again in words/comments, not code.
Apply this “divide-and-conquer” approach until the steps are simple enough to code.
Write code
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

43. Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

44. Top-Down Approach to Program Development
Start by writing down the main steps (in words/comments, not code) of a program. Like a paragraph in an essay.
For each difficult main step, break it down into smaller steps. Again in words/comments, not code.
Apply this “divide-and-conquer” approach until the steps are simple enough to code.
Write code one step at a time
Debug each step if necessary
Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

45. Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

46. Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

47. Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

48. Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?

49. Software infrastructure: support integration between physical space and virtual computing space, adapting to different smart environment, etc.
Sensors: acquire user context such as techniques to estimate location from , etc.
Context-aware applications: how can we use the context information to make application or everyday objects intelligent
Security and privacy: user context information (where you are) should be protected.
Human experience: user experience in ubicomp environment – how to evaluate it quantitatively or qualitatively?
Ubiquitous data access: access information from any devices in any modalities from any networks
Coping with uncertainty: sensors may have errors (GPS).
Social computing: ubicomp is used in everyday physical / virtual activities. It will affect your social activities. How can we use it to improve your social lives?