C if-else Statements

If else statements in C is also used to control the program flow based on some condition, only the difference is: it's used to execute some statement code block if the expression is evaluated to true, otherwise executes else statement code block.

The basic format of if else statement is:

Syntax:
if(test_expression)
{
   //execute your code
}
else
{
   //execute your code
}

Figure - Flowchart of if-else Statement:

c-if-else

Example of a C Program to Demonstrate if-else Statement

Example:
#include<stdio.h>

void main()
{
  int a, b;

  printf("Please enter the value for a:");
  scanf("%d", &a);

  printf("\nPlease the value for b:");
  scanf("%d", &b);

  if (a > b) {  
    printf("\n a is greater");
  } else {  
    printf("\n b is greater");
  }
}
Program Output:

c-if-else statement 1

Example:
#include<stdio.h>

void main() {
  int num;
  printf("Enter the number:");
  scanf("%d", &num);

  /* check whether the number is negative number */
  if (num < 0)
    printf("The number is negative.");
  else
    printf("The number is positive."); 
}
Program Output:

c-if-else-statement 2

if-else Statements in C - Video Tutorial

To understand "C if-else Statements" in more depth, please watch this video tutorial.