C if else if ladder

if else if ladder in C programming is used to test a series of conditions sequentially. Furthermore, if a condition is tested only when all previous if conditions in the if-else ladder are false. If any of the conditional expressions evaluate to be true, the appropriate code block will be executed, and the entire if-else ladder will be terminated.

Syntax:

// any if-else ladder starts with an if statement only
if(condition) {
        
}
else if(condition) { 
 // this else if will be executed when condition in if is false and
 // the condition of this else if is true
}
.... // once if-else ladder can have multiple else if 
else { // at the end we put else 
        
}

Working Flow of the if-else-if ladder:

1. The flow of the program falls into the if block.
2. The flow jumps to 1st Condition
3. 1st Condition is tested respectively:
   • If the following Condition yields true, go to Step 4.
   • If the following Condition yields false, go to Step 5.
4. The present block is executed. Goto Step 7.
5. The flow jumps to Condition 2.
   • If the following  Condition yields true, go to step 4.
   • If the following Condition yields false, go to Step 6.
6. The flow jumps to Condition 3.
   • If the following Condition yields true, go to step 4.
   • If the following Condition yields false, execute the else block. Goto Step 7.
7. Exits the if-else-if ladder.

if else if ladder flowchart  in C

Note:  A if-else ladder can exclude else block.

Example 1: Check whether a number is positive, negative or 0

C

// C Program to check whether
// a number is positive, negative
// or 0 using if else if ladder
#include <stdio.h>

int main()
{
    int n = 0;

    // all Positive numbers will make this
    // condition true
    if (n > 0) {
        printf("Positive");
    }

    // all Negative numbers will make this
    // condition true
    else if (n < 0) {
        printf("Negative");
    }

    // if a number is neither Positive nor Negative
    else {
        printf("Zero");
    }
    return 0;
}

Output

Zero

Example 2: Calculate Grade According to marks 

C

// C Program to Calculate Grade According to marks
// using the if else if ladder
#include <stdio.h>
int main()
{
    int marks = 91;
    if (marks <= 100 && marks >= 90)
        printf("A+ Grade");
    else if (marks < 90 && marks >= 80)
        printf("A Grade");
    else if (marks < 80 && marks >= 70)
        printf("B Grade");
    else if (marks < 70 && marks >= 60)
        printf("C Grade");
    else if (marks < 60 && marks >= 50)
        printf("D Grade");
    else
        printf("F Failed");
    return 0;
}

Output

A+ Grade