1. Programming Fundamentals

2. If you have programming experience (in any language other than C),
Click here to skip the Programming Fundamentals part.
If you are new to programming…, continue reading.

3. Objectives Understand the different types of programming languages.
Understand the basic procedures in a program as input, processing and output.
Understand the importance of variables.
Understand a basic map of the program development cycle.

4. Computer Components CPU Central Processing Unit
RAM (Random Access Memory)
Mass storage devices
Input devices
Output Devices

5. Software
Software is comprised of instructions that get a computer to perform a task.
Application Software
Word Processors
Spreadsheets
Painting programs
Web browsers, programs
System Software
Operating Systems
Windows
Macintosh OS
Unix
Linux
Drivers

6. Programming Languages
Programming languages allow programmers to code software.
The three major families of languages are:
Machine languages
Assembly languages
High-Level languages

7. Machine Languages Comprised of 1s and 0s
The “native” language of a computer
Difficult to program – one misplaced 1 or 0 will cause the program to fail.
Example of code:

8. Assembly Languages A step towards easier programming.
Comprised of a set of elemental commands
tied to a specific processor.
Assembly language code needs to be translated to machine language before the computer processes it.
Example: ADD ,

9. High-Level Languages
High-level languages represent a giant leap towards easier programming.
The syntax of HL languages is similar to English.
Historically, we divide HL languages into two groups:
Procedural languages
Object-Oriented languages (OOP)

10. Procedural Languages Procedural languages
The focus of such languages is on sequence of activities to be carried out.
Based on specifying the steps the program must take to reach the desired state.
Examples include C, COBOL, Fortran, LISP, Perl, HTML, VBScript

11. Object-Oriented Languages
Focus on modeling data.
Programmers code using “blueprints” of data models called classes.
Examples of OOP languages include C++, Visual Basic.NET and Java.

12. Compiling All HL programs need to be translated to machine code
so that a computer can process the program.
Programs may be translated using
a compiler:
translated all at once
An interpreter
translated line by line
Compiled programs typically execute more quickly than interpreted programs, but have a slower translation speed.
On the other hand, interpreted programs generally translate quicker than compiled programs, but have a slower execution speed.

13. Programming Example
Simple programming problem: Convert a length from feet into meters.
Pseudocode:
Input the length of an item, LengthInFeet, in feet and Compute the length of the item in meters:
Write “Enter the length in feet”
Input LengthInFeet
Set LengthInMeters = LengthInFeet * .3048
Write LengthInMeters

14. Programming Example Partial Code in C: float LengthInFeet;
LengthInMeters = LengthInFeet * .3048;
printf (“%f”, LengthInMeters);

15. Input & Variables Input operations get data into the programs
A user is prompted to enter data:
Write “Enter the length in feet”
Input LengthInFeet
Computer programs store data in named sections of memory called variables.
In the example above, the variables are named LengthInFeet & LengthInMeters.
The value of a variable can, and often does, change throughout the program.

16. Variables
Needed because we might want the program to run using different values:
E.g. we might want to calculate LengthInMeters for different values of LengthInFeet
Each value for which computation is to be carried out will be stored in the variable LengthInFeet one-by-one
Referring to the variable LengthInFeet by its name gives the value stored in it.

17. Constants
Many a time we need to used fixed values for certain computations.
E.g. in the program given above
the conversion from miles to meters requires the length in miles to be multiplied by .3048
a value that doesn’t (need to) change
Such values are constants
We may also give names to constants: such constants are called named constants

18. Types of Data Numeric Data
Integer data, I.e., whole numbers,
Floating point data – have a decimal point , -5.0
Character data (alphanumeric)
All the characters you can type at the keyboard
Letters & numbers not used in calculations
Boolean data
TRUE/FALSE

19. Data Processing and Output
LengthInMeters = * LengthInFeet
The above statement is a processing statement.
Take the value in the variable LengthInFeet,
Multiply by .3048, and
Set the value of the variable LengthInMeters to the result of the multiplication.
Also stated as assign the result of multiplication to the variable LengthInMeters
Write LengthInMeters
Output the value in LengthInMeters to the monitor.

20. Assignment Statements
If the variable being assigned to already contains a data value,
the previously stored value is overwritten
E.g. the following statements:
Age= 12;
Age=15;
Have an effect of storing 15 in the variable Age.
Reason: The value 12 (stored as an effect of the first assignment statement) gets overwritten after the execution of the second statement.

21. Assignment Statements
The statement
Age = Age + 1
Changes the value of the variable Age in such a way that the new value is one greater than the previous value.
Working: Take the value of Age, add 1, and store the result back in the same variable.

22. Operations on Data
Operator is a symbol that is used to perform certain operations
Data values on which operation is performed are termed as operands
Operators generally work on many types of variables or constants,
though some are restricted to work on certain types.
some may even exhibit different behaviors with different data types
Operators in C may be:
Unary: Work on single operand
Binary: Work on two operands
Ternary: Work on three operands

23. Operators
C, like most programming languages, supports operators to carry out various kinds of operations
We have operators for:
Arithmetic operations
Type Conversions
Performing Comparisons
Performing Logical Operations
Working on individual bits of data
And many more…

24. Precedence of Operators
Operator precedence:
A set of rules decide the order of operations in an expression
Like BODMAS rule in mathematics
Operator Precedence clarifies unambiguously, which operations should be performed first in a given expression.
Parentheses i.e. () can always be used to improve clarity

25. Associativity of Operators
Operator Associativity:
Rule used for two operators of equal precedence (i.e. same importance)
Associativity may be either of the following
left to right: left operator is evaluated first
right to left: right operator is evaluated first

26. Structured Programming
A method for designing and coding programs in a systematic, organized manner.
It combines
the principles of top-down design,
modularity and
the use of the three accepted control structures of
sequence,
repetition and
selection.

27. Control Structures Sequence –in sequential order.
The simplest of control structures –
start at the beginning and continue in sequential order.
Selection – selectively execute statements
Called a branch,
it requires a condition to determine when to execute statements.

28. Control Structures Repetition – repeat statements more than once
Called a loop,
It needs a stop condition,
I.e, the program will continue to loop (repeatedly execute a set of statements) until some condition is met.

29. Counter-Controlled Loop: (Definite Repetition)
If it is known in advance exactly how many times a loop will execute, the repetition is said to be counter-controlled
Counter-controlled loop:
Execute a set of statements repeatedly a specified number of times
The counter may be advanced according to programmers requirements .

30. Event-Controlled Loop: (Indefinite Repetition)
If it is NOT known in advance exactly how many times a loop will execute, the loop is said to be event-controlled.
An event-controlled loop
Terminates when some event occurs.
The event may be based upon:
User input
Results of calculation
And many more….

31. Steps in Developing a Program
Analyze the problem
Design the program
Code the program
Test the program

32. Step-1 Analyze the Problem
Brewster’s Thousands
The problem: Brewster wants to invest money at a local bank. There are many options such as interest rates, terms of deposit, compounding frequencies. He needs a program to compute, for any given initial investment, the final maturity (value) of the deposit.
What are the inputs? (given data)
What are the outputs? (required data)
How will we calculate the required outputs from the given inputs?

33. Step-2 Design the Program
Create an outline of the program
An algorithm – a step by step procedure that will provide the required results from the given inputs.
Algorithm Examples: Instructions on how to make a cake, use the bank’s ATM, etc.

34. Step-3 Code the Program
Once the design is completed, write the program code.
Code is written in some programming language such as BASIC, Pascal, C++, Java, etc.

35. Errors in Development Forgetting punctuation, misspelling keyword
While writing a program, certain errors may get induced in the code.
Errors may be categorized as :
Syntactical Errors – Incorrect Syntax (wrong grammar), i.e., breaking the rules of how to write the language
Forgetting punctuation, misspelling keyword
The program will not run at all with syntax errors
Semantic Errors: Incorrect Logic:
Using an incorrect formula, incorrect sequence of statements, etc.
The program runs, but does not produce the expected results.

36. Step-4 Testing the program
Purpose: Locate any errors (bugs) / problems
Most of the work should be done before the phase begins – creating of a testing document – telling what to test & how.
Two types of testing:
Testing for errors
Quality testing
Testing is done throughout the development cycle
Desk-checking, or code walkthrough is performed to locate errors in the code.
Pretend you are the computer and execute your own code.
Ultimate test is to run the program to see if the outputs are correct for the given inputs.

37. Good Programming Practice
It is best not to take the “big bang” approach to coding.
Use an incremental approach by writing your code in incomplete, yet working, pieces.
For example, for your projects,
Don’t write the whole program at once.
Just write enough to display the user prompt on the screen.
Get that part working first (compile and run).
Next, write the part that gets the value from the user, and then just print it out.

38. Modular Programming
Determine the major tasks that the program must accomplish.
Each of these tasks will be a module.
Some modules will be complex themselves, and they will be broken into sub-modules,
and those sub-modules may also be broken into even smaller modules.
This is called top-down design

39. Code Modules
A module is an independent, self-contained section of code that performs a single task.
The main module is the module that drives the application.
It “controls” all other modules.
Typically, the main module calls other modules in order to have them perform certain tasks.

40. Program Control & Modules
When the main module calls another module, program control transfers to the called module.
Program control cedes back to the main module when the called module finishes.

41. Structure Chart
A structure chart shows what modules exist and how they are related.
A structure chart is a top-down modular design tool
It is used in structured programming to arrange program modules into a tree
It’s a good idea to keep modules short – about 1 page per module.
We will have very small modules while getting comfortable with programming.

42. Documentation Internal Documentation
Comments explain to the reader the logic and decision processes of the programmer.
Comments are ignored by an interpreter or compiler.
External Documentation
External documentation includes a user’s guide and, typically, a more technical system administrator’s guide.

43. Over to C Fundamentals…

44. C Fundamentals

45. Objectives History of C Characteristics of C
Converting a C Program to Executable
Dissecting a simple C Program
Defining Variables in C
Printing Out and Inputting Variables
Constants & Literals

46. History of C
Developed by Brian Kernighan and Dennis Ritchie of AT&T Bell Labs in 1972
In 1983 the American National Standards Institute began the standardization process
In 1989 the International Standards Organization continued the standardization process
In 1990 a standard was finalized, known simply as “Standard C”

47. Features of C C can be thought of as a “high level assembler”
Most popular programming language for writing system software
Focus on the procedural programming paradigm, with facilities for programming in a structured style
Low-level unchecked access to computer memory via the use of pointers
And many more…

48. Writing C Programs
A programmer uses a text editor to create or modify files containing C code.
Code is also known as source code.
A file containing source code is called a source file.
After a C source file has been created, the programmer must invoke the C compiler before the program can be executed (run)

49. Getting an executable program
The process of conversion from source code to machine executable code is a multi step process.
If there are no errors in the source code, the processes called compilation & linking produce an executable file
To execute the program, at the prompt, type
<executable file name>

50. Conversion from .C to executable
Preprocessing
Compilation
Linking

51. Stage 1: Preprocessing Performed by a program called the preprocessor
Modifies the source code (in RAM) according to preprocessor directives (preprocessor commands) embedded in the source code
Strips comments and white space from the code
The source code as stored on disk is not modified

52. Stage 2: Compilation Performed by a program called the compiler.
Checks for syntax errors and warnings
Translates the preprocessor-modified source code into object code (machine code).
Saves the object code to a disk file
If any compiler errors are received, no object code file will be generated.
An object code file will be generated if only warnings, not errors, are received.

53. Stage 3: Linking
Combines the program object code with other object code to produce the executable file.
The other object code can come from the
Run-Time Library
other libraries
or object files that you have created.
Saves the executable code to a disk file.
If any linker errors are received, no executable file is generated.

54. Developing a C Program Editor Preprocessor Compiler Linker
Modified Source Code in RAM
Source File pgm.c
Program Object Code File
Executable File
Preprocessor
Compiler
Linker
Editor

55. A Simple C Program /* Filename: hello.c Author: --------
Date written: --/--/----
Description: This program prints the greeting “Hello, World!” */
#include <stdio.h>
int main ( void ) {
printf ( “Hello, World!\n” ) ;
return 0 ; }

56. Structure of a C Program
program header comment
preprocessor directives (if any)
int main ( ) {
statement(s)
return 0 ; }

57. Explanation
tells compiler about standard input and output functions (i.e. printf + others)
#include <stdio.h> /* comment */
int main(void) {
printf("Hello\n");
printf("Welcome to the Course!\n");
return 0; }
main function
“begin”
flag success to operating system
Hello
Welcome to the Course!
“end”

58. Tokens The smallest element in the C language is the token.
It may be a single character or a sequence of characters to form a single item.

59. Tokens can be any of: Numeric Literals Character Literals
String Literals
Keywords
Names (identifiers)
Punctuation
Operators

60. Numeric Literals
Numeric literals are an uninterrupted sequence of digits
May contain
A period,
A leading + or – sign
A scientific format number
A character to indicate data type
Examples:
123
98.6

61. Character Literals Singular! One character defined character set.
Surrounded on the single quotation mark.
Examples:
‘A’
‘a’
‘$’
‘4’

62. String Literals
A sequence characters surrounded by double quotation marks.
Considered a single item.
Examples:
“UMBC”
“I like ice cream.”
“123”
“CAR”
“car”

63. Keywords Sometimes called reserved words.
Are defined as a part of the C language.
Can not be used for anything else!
Examples:
int
while
for

64. Reserved Words (Keywords) in C
auto
case
const
default
double
enum
float
goto
break
char
continue do
else
extern
for if
int
register
short
sizeof
struct
typedef
unsigned
volatile
long
return
signed
static
switch
union
void
while
All the C keywords are in small case

65. Names / Identifiers
Variables must be declared before use and immediately after “{”
Can be of anything length, but only the first 31 are significant (A very long name is as bad as a very short, un-descriptive name).
Are case sensitive: abc is different from ABC
Must begin with a letter and the rest can be letters, digits, and underscores.
Cannot be a reserved word.

66. Which Are Legal Identifiers?
AREA area_under_the_curve
3D num45
Last-Chance #values
x_yt pi
num$ %done
lucky*** continue
Float integer

67. Punctuation
Semicolons, colons, commas, apostrophes, quotation marks, brackets, and parentheses.
; : , ‘ “ { } ( )

68. Things to remember Statements are terminated with semicolons
Indentation is ignored by the compiler
C is case sensitive - all keywords and Standard Library functions are lowercase

69. Variables and Constants in C

70. Topics Variables Naming Declaring Using The Assignment Statement
Constants
Data Input & Output

71. Naming Conventions Begin variable names with lowercase letters
Use meaningful names
Separate “words” within identifiers with underscores or mixed upper and lower case.
Use all uppercase for symbolic constants (used in #define preprocessor directives).
Be consistent!
In addition to the conventions one must follow all the naming rules as discussed in previous sessions.
Note: symbolic constants are not variables, but make the program easier to read.

72. Declaring Variables
All variables need to be declared before they are used.
The declaration statement includes (apart from other information) the data type of the variable.
Examples of variable declarations:
int meatballs ;
float area ;

73. Declaring Variables age FE07 int garbage the variable name
When we declare a variable
Space is set aside in memory to hold a value of the specified data type
That space is associated with
the variable name
a unique address
Visualization of the declaration
int age ;
age
FE07
int
garbage
It is required to declare variables before using
as compiler needs this information
Purpose!!!

74. More About Variables Basic data types available in C are:
char: stores single character
int: stores whole numbers
float: store floating point numbers
double: store floating point numbers with higher precision

75. Integer Types in C C supports different kinds of integers, like
signed int
unsigned int
long int
short int
And more…
Limits depend upon size in bytes which in turn depends upon environment
maxima and minima defined in “limits.h”
We can work with different bases as well (octal, hexadecimal).

76. The int Data Type (Contd.)
Use
scanf (“%i”, &ch) ;
to read a single integer into the variable ch.
printf(“%i”, ch) ;
to display the value of an integer variable.

77. The char Data Type The char data type holds a single character.
char ch;
Example assignments:
char grade, symbol;
grade = ‘B’;
symbol = ‘$’;
The char is held as a one-byte integer in memory. The ASCII code is what is actually stored, so we can use them as characters or integers, depending on our need.

78. The char Data Type (Contd.)
Use
scanf (“%c”, &ch) ;
to read a single character into the variable ch.
printf(“%c”, ch) ;
to display the value of a character variable.

79. char I/O #include <stdio.h> int main ( ) { char ch ;
printf (“Enter a character: “) ;
scanf (“%c”, &ch) ;
printf (“The value of %c\n.”, ch) ;
return 0 ; }
Input: A
Output : The value of A is 65.

80. Real Types In C C supports different kinds of reals
maxima and minima are defined in “float.h”
type format minimum maximum
float %f %e %g FLT_MIN FLT_MAX
double %lf %le %lg DBL_MIN DBL_MAX
long double %Lf %Le %Lg LDBL_MIN LDBL_MAX

81. Notes About Variables
You must not use a variable until you somehow give it a value.
You can not assume that the variable will have a value before you give it one.
Some compilers do, others do not! This is the source of many errors that are difficult to find.

82. Operators in C

83. Arithmetic Operators and their Usage
Name Operator Example
Addition + num1 + num2
Subtraction - initial - spent
Multiplication * fathoms * 6
Quotient of Division / sum / count
Remainder of Division % m % n
% can not be used with reals

84. Relational Operators
< less than
> greater than
<= less than or equal to
>= greater than or equal to
== is equal to
!= is not equal to
Relational expressions evaluate to the integer values:
1 (true) on success
0 (false) on failure

85. Logical Operators
At times we need to test multiple conditions in order to make a decision.
Logical operators combine simple conditions to make complex conditions.
Result into a 0 (false) or 1 (true)
&& AND if ( x > 5 && y < 6 )
|| OR if ( z == 0 || x > 10 )
! NOT if (! (age > 42) )

86. Truth Table for && Expression1 Expression2 Expression1 && Expression2
nonzero
nonzero
nonzero nonzero
Exp1 && Exp2 && … && Expn will evaluate to 1 (true) only if ALL sub-conditions are true.

87. Truth Table for || Expression1 Expression2 Expression1 || Expression2
nonzero
nonzero
nonzero nonzero
Exp1 || Exp2 || … || Expn will evaluate to 1 (true) if any one of the sub-conditions is true.

88. Expression ! Expression
Truth Table for !
Expression ! Expression
nonzero

89. Precedence/Associativity Table
Operator Associativity
() [] -> . left to right
! ~ (cast) * & sizeof right to left
* / % left to right
+ - left to right
<< >> left to right
< <= >= > left to right
== != left to right
& left to right
| left to right
^ left to right
&& left to right
|| left to right
?: right to left
= += -= *= /= %= etc right to left
, left to right
+ - : unary

90. User Interaction in C

91. Functions
Functions are named code blocks that make reusability of code possible.
These are parts of programs that
Perform a well defined task.
At times, expect some information in order to complete the task.
The information is provided in form of parameters (arguments)
Can return a value to convey result / status of execution

92. I/O Example create two integer variables, “a” and “b”
#include <stdio.h>
int main(void) {
int a, b;
printf("Enter two numbers: ");
scanf("%i %i", &a, &b);
printf("%i - %i = %i\n", a, b, a - b);
return 0; }
read two integer numbers into “a” and “b”
write “a”, “b” and “a-b” in the format specified
Enter two numbers: 21 17
= 4

93. Displaying Variables
A Function that allows us to display formatted data:
printf( ).
Needs two pieces of information to display things.
How to display it
What to display
printf( “%f\n”, diameter );

94. printf( “%f\n”, diameter );
The name of the function is “printf”.
Inside the parentheses are two comma separated parameters:
Format specifier: indicates the format in which the output will be produced
%f => a floating point value
\n => a new-line character (escape sequence)
The expression diameter whose value is to be displayed.

95. scanf (“%f”, &meters) ; This function is used to
read values from the standard input; and
Store them in memory.
The scanf( ) function also needs two items:
The input specification “%f”.
The address of the memory location where the information is to be stored.
We can input more than one item at a time if we wish, as long as we specify it correctly!!!
Notice the “&” in front of the variable name. Can you explain its significance!

96. Format Specifiers Why are these required!!!
Format specifiers are normal strings with embedded “conversion specifications” which are placeholders for arguments
Conversion specifications are a ‘%’ and a letter with an optional set of arguments in between the ‘%’ and letter.
Why are these required!!!

97. Selection: the if statement
if ( condition ) {
statement(s) /* body of the if statement */ }
The braces are not required if the body contains only a single statement.
However, they are a good idea and are required by the C Coding Standards.

98. Examples if ( age >= 18 ) { printf(“Vote!\n”) ; } if ( value == 0 )
printf (“The value you entered was zero.\n”);
printf (“Please try again.\n”) ;

99. Some Control Constructs in C

100. Selection: the if-else statement
if ( condition ) {
statement(s) /* the if clause */ }
else
statement(s) /* the else clause */

101. Example if ( age >= 18 ) { printf(“Vote!\n”) ; } else
printf(“Maybe next time!\n”) ;

102. Repetition Structure There are three repetition structures in C: -
the while loop
the for loop
the do-while loop.
Either of these structures may be used for counter-controlled / event-controlled logic, but
The syntax of for loop makes it more suitable for counter-controlled repetition
And, The syntax of while / do-while loops makes them more suitable for event-controlled repetition

103. The while Repetition Structure
while ( condition ) {
statement(s) }
The braces are not required if the loop body contains only a single statement.
However, they are a good idea and are required by the C Coding Standards.

104. while Loop The simplest C loop is the while
Parentheses must surround the condition
Condition could be based on user input or some calculation
Braces must be added if more statements are to be executed
total= 0;
while (number != -1) {
total = total + number;
printf(“Enter another number: “) ;
scanf(“%d”, &number) ; }

105. The for Loop Repetition Structure
The for loop handles details of the counter-controlled loop “automatically”.
The following are handled within the for loop structure
initialization of the the loop control variable,
the termination condition test, and
control variable modification.
for ( i = 1; i < 101; i = i + 1) { }
initialization test modification

106. A for Loop That Counts From 0 to 9
for ( i = 0; i < 10; i = i + 1 ) {
printf (“%d\n”, i) ; }

107. We Can Count Backwards, Too
for ( i = 9; i >= 0; i = i - 1 ) {
printf (“%d\n”, i) ; }

108. Count By 2’s or 7’s or Whatever
for ( i = 0; i < 10; i = i + 2 ) {
printf (“%d\n”, i) ; }

109. The do-while Repetition Structure{
statement(s)
} while ( condition ) ;
The body of a do-while is ALWAYS executed at least once.
Is this true of a while loop?
What about a for loop?

110. Example do { printf (“Enter a number, 0 to terminate: “);
scanf (“%d”, &number) ;
if (number == 1)
printf (“\n Do Something\n”) ;
else if (number == 2)
printf (“\n Do Something Else\n”) ;
} while ( num != 0 );

111. An Equivalent while Loop
printf (“Enter a number, 0 to terminate:“) ;
scanf (“%d”, &number) ;
while ( number != 0 ) {
if (number == 1)
printf (“\n Do Something\n”) ;
else if (number == 2)
printf (“\n Do Something Else\n”) ;
printf (“Enter a number , 0 to terminate:“) ; }
Notice that using a while loop in this case requires a priming read.

112. An Equivalent for Loop
printf (“Enter a positive number, 0 to terminate: “) ;
scanf (“%d”, &number) ;
for ( ; number != 0; ) {
if (number == 1)
printf (“\n Do Something\n”) ;
else if (number == 2)
printf (“\n Do Something Else\n”) ;
printf (“Enter a number , 0 to terminate:“) ; }
A for loop is a very awkward choice here because the loop is event-controlled.

113. So, Which Type of Loop Should One Use?
Use a for loop for counter-controlled repetition.
Use a while or do-while loop for event-controlled repetition.
Use a do-while loop when the loop must execute at least one time.
Use a while loop when it is possible that the loop may never execute.

114. That’s all for now…
We are ready for writing a simple C program.