The document provides examples of different variable types in C programming such as character, integer, floating point, and double precision variables. It also demonstrates how to take user input using scanf and print output using printf. Decision making and selection statements like if, if-else, and switch statements are explained. Operators for equality and relational comparisons are covered. Finally, the while loop construct is introduced as a method of repetition or iteration in C programs.

1. Programming with C
Chapter 2

3. Example - c program to take input
from user using scanf
#include <stdio.h>
main()
{
int number;
printf("Enter an integern");
scanf("%d",&number);
printf("Integer entered by you is %dn", number);
return 0;
}

4. Character (char) variable in C
• #include <stdio.h>
• int main()
{
• char c; // char variable declaration
• c = 'A'; // defining a char variable
printf("value of c is %c", c);
• return 0;
}

5. Integer (int) variable in C
#include <stdio.h>
int main()
{
int i; // integer variable declaration
i = 123; // defining integer variable
printf("value of i is %d", i);
return 0;
}

6. Rules of Precedence
• Expressions contained operators +, -, *, / & % follow
rules of precedence (priority) to perform calculation.
• Multiplication, division and remainder operators are
applied first, while, addition and subtraction are
evaluated next.
• *, /, % are said to be on same level of precedence.
• Operator in expressions contained within pairs of
parenthesis are evaluated first.
• Evaluation proceed from left to right

7. Floating point (float) variable in C
#include <stdio.h>
int main()
{
float f; // floating point variable declaration
f = 12.001234; // defining float variable
printf("value of f is %f", f);
return 0;
}

8. Double precision(double) floating
point variable in C
#include <stdio.h>
int main()
{
double d; // double precision variable declaration
d = 12.001234; // defining double precision variable
printf("value of d is %e", d);
return 0;
}

9. Simple Calculator performing
Basic Athematic Operations
#include <stdio.h>
int main()
{
int first, second, add, subtract, multiply;
float divide;
printf("Enter two integersn");
scanf("%d%d", &first, &second);
add = first + second;
subtract = first - second;
multiply = first * second;
divide = first / (float)second; //typecasting
printf("Sum = %dn",add);
printf("Difference = %dn",subtract);
printf("Multiplication = %dn",multiply);
printf("Division = %.2fn",divide);
return 0;
}

10. Operator Precedence
• Parenthesis have highest level of precedence.
• ( ( a + b ) + c )
Operator Operations Order of Evaluation (precedence)
( ) Parenthesis Evaluated first. If nested then inner most
evaluated first.
* Multiplication
Evaluated second. If several they are
evaluated form left to right
/ Division
% Remainder
+ Addition Evaluated last. If there are several, they
are evaluated left to right
- Subtraction Evaluated last. If there are several, they
are evaluated left to right

11. Sample Algebra & C Expressions
Algebra C Programming
m = a + b + c + d + e
5
m = (a + b + c + d + e ) / 5; end with a ; colon
Y = mx + b Y = m * x + b;
❸ ❷ ❷ Precedence
Z = pr%q + w/x - y Z = p * r % q + w / x – y;
❻ ❶ ❷ ❹ ❸ ❺ Precedence
Order precedence?
Y = a * x * x + b * x + c; Nested operators follow L-R Rule
Solve as per precedence?
Y = 2 * 5 * 5 + 3 * 5 + 7;

12. Decision Making
• Executable C statements either perform actions such as
calculations or make decisions.
• For example: Exam Grade is greater than or equal to 60
Marks, if statements is correct, program will print “Pass”
otherwise “Fail”.
• IF ( Marks = 60 ) then Pass Else Fail
• IF (Marks => 60 ) then Pass Else Fail
• If condition is met means condition is true, the statement is
executed
• If the condition is not met, the body statement is not
executed

13. Equality Operators & Relational
Operators
• Conditions in if statement are formed by using the equality
operators and relational operators.
• The relational operators have the same level of precedence
and they associate left to right
• The equality operators have a lower level of precedence than
the relational operators.

14. Equality & Relational Operators
Algebraic equality or
relational operator
C equality or
relational
operator
Example of
C
condition
Meaning of C condition
Equality operators
= == X == y x is equal to y
≠ != X != y x is not equal to y
Relational operators
> > x > y X is greater than y
< < X < y X is less than y
≥ >= X >= y X is greater than or equal to
y
≤ <= X <= y X is less than or equal to y

15. Program to check odd or even using modulus operator
#include <stdio.h>
int main()
{
int n;
printf("Enter an integern");
scanf("%d", &n);
if (n%2 == 0)
printf("Evenn");
else
printf("Oddn");
return 0;
}

17. Results

18. Selection statements
• C provides three types of selection structures
in the form of statements.
1) If statement
The if selection statement either performs
(selects) an action if a condition is true
• Or skips the action if the condition is false.
• Also called a single-selection statement

19. • if (grade >= 60)
• {
• printf(“Passedn”);
• } //end if

20. 2) If…else statement
This selection statement performs an action if a
condition is true and performs a different action
if the condition is false (called else).
Also called a double-selection statement,
because it selects among many different actions.

21. • If student’s grade is greater than or equal to 60
• Print “passed”
• Else
• Print “failed”
Example:
if (grade >= 60)
{
printf(“Passedn”);
} //end if
else {
printf(“Failedn”); } // end else

22. • #include <stdio.h>
•
• main()
• {
• int x = 1;
•
• if ( x == 1 )
• printf("x is equal to one.n");
• else
• printf("For comparison use == as = is the assignment operator.n");
•
• return 0;
• }

23. 3) The switch statement
The switch statement performs one of many
different actions depending on the value of an
expression.
Also called a multi-selection statement; because
it selects among many different actions.

24. Loop or repetition statement
• While loop
• While repetition statement specifies that an action is to be
repeated while a condition is true.
• When condition will become false.
• The repetition terminates.
• The first statement after the repetition statement executes.

25. • #include <stdio.h>
•
• main()
• {
• int value = 1;
•
• while(value<=3)
• {
• printf("Value is %dn", value);
• value++;
• }
•
• return 0;
• }

26. • Output:
Value is 1
Value is 2
Value is 3