Explain Nested if-else statement in C language

A ‘nested if’ is an if statement that is the object of either if (or) an else. ‘if’ is placed inside another if (or) else.

Syntax

Refer the syntax given below −

if (condition1){
   if (condition2)
      stmt1;
   else
      stmt2;
}
else{
   if (condition3)
      stmt3;
   else
      stmt4;
}

Example

Given below is the C program to execute Nested If Else conditional operators −

#include<stdio.h>
void main (){
   int a,b,c,d;
   printf("Enter the values of a,b,c: \n");
   scanf("%d,%d,%d",&a,&b,&c);
   if((a>b)&&(a>c)){//Work with 4 numbers//
      if(a>c){
         printf("%d is the largest",a);
      } else {
         printf("%d is the largest",c);
      }
   } else {
      if(b>c){
         printf("%d is the largest",b);
      } else {
         printf("%d is the largest",c);
      }
   }
}

Output

You will see the following output −

Enter the values of a,b,c: 3,5,8
8 is the largest

Example

Following is the C program to check the number is positive or negative −

#include <stdio.h>
int main(){
   int num;
   printf("Enter a number:\n ");
   scanf ("%d ", &num);
   if(num > 0){
      printf("This is positive num:%d\n", num);
   }
   else if(num < 0){
      printf("This is a negative num:%d",num);
   } else {
      printf("This is a zero:%d",num);
   }
   return 0;
}

Output

You will see the following output −

Run 1: Enter a number:
23
23=This number is positive
Run 2: Enter a number:
-56
-56=This number is negative