Conditional Branching : If....Else in c

 

1. if Statement :

The syntax of the if statement in C programming is:

if (test expression)
{
// statements to be executed if the test expression is true
}

How if statement works?

• If the test expression is evaluated to true, statements inside the body of if are executed.
• If the test expression is evaluated to false, statements inside the body of if are not executed.

Example :
#include <stdio.h>
void main()
{
    int number;

    printf("Enter an integer: ");
    scanf("%d", &number);

    // true if number is greater than 0

    if (number > 0)
    {

        printf("You entered %d.\n", number);

    }
    printf("Sign of Good Learner",);
}

First run:
Enter an integer: 20
You entered 20
Sign of Good Learner

Second run:
Enter an integer: -10
Sign of Good Learner


2. if...else Statement :

The syntax of the if...else statement in C programming is:

if (test expression)
{

// statements to be executed if the test expression is true

}
else
{

// statements to be executed if the test expression is false

}

How if...else statement works?

If the test expression is evaluated to true,
• statements inside the body of if are executed.
• statements inside the body of else are skipped from execution.

If the test expression is evaluated to false,
• statements inside the body of else are executed
• statements inside the body of if are skipped from execution.
Example :
#include <stdio.h>
void main()
{
    int number;

    printf("Enter an integer: ");
    scanf("%d", &number);

    if (number > 0)
    {

        printf("You entered Positive Number");

    }
    else
    {

        printf("You entered Negative Number");

    }
}

First run:
Enter an integer: 20
You entered Positive Number.

Second run:
Enter an integer: -10
You entered Negative Number
    
3. if...else Ladder:

The if...else statement executes two different codes depending upon whether the test expression is true or false. Sometimes, a choice has to be made from more than 2 possibilities.

The if...else ladder allows you to check between multiple test expressions and execute different statements.



The syntax of the if...else Ladder statement in C programming is:

if (test expression)
{

// statements to be executed if the test expression is true

}
else if(test expression)
{

// statements to be executed if the test expression is true in else if

}
else
{

// statements to be executed if the test expression is false

}

Example :
#include <stdio.h>
void main()
{
    int number;

    printf("Enter an integer: ");
    scanf("%d", &number);

    if (number > 0)
    {
        printf("You entered Positive Number");
    }
    else if (number < 0)
    {
        printf("You entered Negative Number");
    }
    else
    {
        printf("You entered Zero");
    }
}

First run:
Enter an integer: 20
You entered Positive Number.

Second run:
Enter an integer: -10
You entered Negative Number

Third run:
Enter an integer: 0
You entered Zero