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C++ if else if Ladder

Last Updated : 02 Jan, 2025

In C++, the if-else-if ladder helps the user decide from among multiple options. The C++ if statements are executed from the top down. As soon as one of the conditions controlling the if is true, the statement associated with that if is executed, and the rest of the C++ else-if ladder is bypassed. If none of the conditions is true, then the final statement will be executed.

Let's take a look at an example:

#include <iostream> 
using namespace std; 
  
int main()  { 
    int i = 20;
  
    // If - else ladder
    if (i == 10) 
        cout << "i is 10"; 
    else if (i == 15) 
        cout << "i is 15"; 
    else if (i == 20) 
        cout << "i is 20"; 
    else
        cout << "i is not present"; 
  
    return 0; 
} 

Explanation: In this program, compiler first checks if i is 10. Since i is not 10, it then moves to the next condition and checks if i is 15. Since i is also not 15, it checks if i is 20. Here the condition becomes true and the associated block is executed.

if (condition1) {
// Statements 1
}
else if (condition2) {
// Statements 2
}
else {
// Else body
}

where,

• condition1, condition2: Contitions to be tested.
• statements 1, statements 2: Code block corresponding to each condition.

An if-else ladder can exclude else block.

The working of if else if ladder can be understood using the following flowchart:

• If Condition 1 evaluates to true, Statement 1 is executed, and the rest of the else if and else conditions are skipped.
• If Condition 1 is false, Condition 2 is evaluated.
• If Condition 2 evaluates to true, Statement 2 is executed, and the else block is skipped.
• If Condition 2 is also false, the Else Body is executed.
• After completing the if-else-if ladder, the statement just below the if are executed.

The below examples demonstrate the common usage of if else if ladder in C++ programs:

#include <iostream>
using namespace std;

int main() {
    int n = -8;

    // Check if the number is positive
    if (n > 0)
        cout << "Positive";
  
    // Check if the number is negative
    else if (n < 0)
        cout << "Negative";
  
    // If the number is neither positive nor negative
    else
        cout << "Zero";

    return 0;
}

As you may also have noticed, if the body contains only single statement, we can skip the braces {}.

#include <iostream>
using namespace std;

int main() {
    int day = 4;

    // Determine the day name using if-else if ladder
    if (day == 1) {
        cout << "Monday";
    } else if (day == 2) {
        cout << "Tuesday";
    } else if (day == 3) {
        cout << "Wednesday";
    } else if (day == 4) {
        cout << "Thursday";
    } else if (day == 5) {
        cout << "Friday";
    } else if (day == 6) {
        cout << "Saturday";
    } else if (day == 7) {
        cout << "Sunday";
    } else {
        cout << "Invalid day number";
    }

    return 0;
}

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