1. EECE.2160 ECE Application Programming
Instructors:
Dr. Michael Geiger & Dr. Peilong Li
Spring 2017
Lecture 26:
Nested structures

2. ECE Application Programming: Lecture 26
Lecture outline
Announcements/reminders
Program 7 due Friday, 4/7
Today’s class
2-D arrays and functions
Program 7 intro
Nested structures
Start PE4 (Structures)
7/31/2019
ECE Application Programming: Lecture 26

3. 2-D arrays and functions
When passing 2-D array to function, can omit first dimension (rows) but must list columns
Example:
// Assume n = # of rows
int f(int arr[][4], int n);
int main() {
int x[3][4];
f(x, 3);
... }
7/31/2019
ECE Application Programming: Lecture 22

4. ECE Application Programming: Lecture 26
Program 7 overview
Store 21 * 51 grid in 2-D character array
Each character is grid line ('-', '|', or '+'), space (' '), or star ('*')
Stars represent “boxes” added to grid
User inputs x, y coordinates of lower left corner + width/height of box
Commands (all strings)
“add”: add a box to the grid
“print”: print current state of grid + added boxes
“reset”: reset grid to original state (no boxes)
“exit”: end the program
Functions
resetGrid(char grid[][NCols]): resets grid to hold only grid lines & spaces
addBox(char grid[][NCols], int x, int y, int width, int height): adds new box to grid
printGrid(char grid[][NCols]): output current grid state to screen
7/31/2019
ECE Application Programming: Lecture 26

5. Program 7 overview (continued)
A few tricky things about the program:
Don’t assume commands match just because first few characters match
e.g. if I type “resetting”, your grid shouldn’t be reset
Boxes can lie partially inside grid
e.g. box with origin (-1, -1), width 5, height 5
Program must check for such cases and only modify coordinates inside grid
Failure to check for these cases leads to either
Boxes “wrapping around” grid, or
Program crashing when you go outside your grid array
7/31/2019
ECE Application Programming: Lecture 26

6. ECE Application Programming: Lecture 26
Review: Structures
User-defined types; example:
typedef struct {
char first[50];
char middle;
char last[50];
unsigned int ID;
double GPA;
} StudentInfo;
Can define variables of that type
Scalar: StudentInfo student1;
Array: StudentInfo classList[10];
Pointer: StudentInfo *sPtr = &student1;
Access members using
Dot operator: student1.middle = ‘J’;
Arrow (if pointers): sPtr->GPA = 3.5;
Typically passed to functions by address
7/31/2019
ECE Application Programming: Lecture 26

7. ECE Application Programming: Lecture 26
Nested structures
Structures can contain other structures:
typedef struct {
char first[50]; // First name
char middle; // Middle initial
char last[50]; // Last name
} Name;
Name sname; // Student name
unsigned int ID; // ID #
double GPA; // Grade point
} SINew;
Will need multiple dot operators to access field within nested structure
Given SINew s1;
s1.sname  Name structure within s1
s1.sname.middle  middle initial of name within s1
7/31/2019
ECE Application Programming: Lecture 26

8. ECE Application Programming: Lecture 26
PE4 (Structures)
Given header files, main program
Complete specified functions
For the Name structure
void printName(Name *n): Print the name pointed to by n, using format <first> <middle>. <last>
void readName(Name *n): Prompt for and read a first, middle, and last name, and store them in the structure pointed to by n
SINew functions on next slide
7/31/2019
ECE Application Programming: Lecture 26

9. Today’s exercise (continued)
Given header files, main program
Complete specified functions
Name functions on previous slide
For the SINew structure
void printStudent(SINew *s): Print information about the student pointed to by s
void readStudent(SINew *s): Prompt for and read information into the student pointed to by s
void printList(SINew list[], int n): Print the contents of an array list that contains n StudentInfo structures
int findByLName(SINew list[], int n, char lname[]): Search for the student with last name lname in the array list. Return the index of the structure containing that last name, or -1 if not found
int findByID(SINew list[], int n, unsigned int sID): Search for the student with ID # sID in the array list. Return the index of the structure containing that last name, or -1 if not found
7/31/2019
ECE Application Programming: Lecture 26

10. ECE Application Programming: Lecture 26
Next time
Finish PE4
Dynamic memory allocation
Reminders:
Program 7 due Friday, 4/7
7/31/2019
ECE Application Programming: Lecture 26