Else–if ladder in C++ - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of an else-if ladder with integer input

What is the output of the following C++ code when num = 15?

C++

#include <iostream>
using namespace std;

int main() {
    int num = 15;
    if (num < 10) {
        cout << "Less than 10";
    } else if (num < 20) {
        cout << "Between 10 and 19";
    } else if (num < 30) {
        cout << "Between 20 and 29";
    } else {
        cout << "30 or more";
    }
    return 0;
}

A Between 10 and 19

B Less than 10

C Between 20 and 29

D 30 or more

💡 Hint

Check which condition is true first in the else-if ladder.

The variable num is 15. The first condition (num < 10) is false. The second condition (num < 20) is true, so it prints "Between 10 and 19" and skips the rest.

❓ Predict Output

intermediate

Output when multiple else-if conditions are false

What will the program print when score = 85 in this else-if ladder?

C++

#include <iostream>
using namespace std;

int main() {
    int score = 85;
    if (score >= 90) {
        cout << "Grade A";
    } else if (score >= 80) {
        cout << "Grade B";
    } else if (score >= 70) {
        cout << "Grade C";
    } else {
        cout << "Fail";
    }
    return 0;
}

A Grade A

B Grade B

C Grade C

D Fail

💡 Hint

Check the conditions from top to bottom carefully.

score is 85. The first condition (score >= 90) is false. The second condition (score >= 80) is true, so it prints "Grade B".

🔧 Debug

advanced

Identify the error in this else-if ladder

What error will this code produce when compiled?

C++

#include <iostream>
using namespace std;

int main() {
    int x = 5;
    if (x > 0)
        cout << "Positive";
    else if x == 0 {
        cout << "Zero";
    } else {
        cout << "Negative";
    }
    return 0;
}

A Logical error, prints wrong output

B Runtime error due to uninitialized variable

C No error, prints "Positive"

D Syntax error due to missing parentheses in else if condition

💡 Hint

Check the syntax of the else-if statement carefully.

In C++, the condition in else if must be enclosed in parentheses. The code has else if x == 0 without parentheses, causing a syntax error.

🧠 Conceptual

advanced

Understanding else-if ladder flow

Consider this else-if ladder. Which statement is true about how it executes?

C++

if (a > b) {
    // block 1
} else if (a == b) {
    // block 2
} else {
    // block 3
}

A All blocks can execute if conditions are true

B Blocks 1 and 3 can execute together

C Only one block executes depending on the first true condition

D Blocks 2 and 3 always execute together

💡 Hint

Think about how else-if ladder chooses which block to run.

In an else-if ladder, only the first true condition's block runs. The rest are skipped.

❓ Predict Output

expert

Output of nested else-if ladder with multiple variables

What is the output of this C++ program?

C++

#include <iostream>
using namespace std;

int main() {
    int x = 10, y = 20;
    if (x > y) {
        cout << "X is greater";
    } else if (x == y) {
        cout << "X equals Y";
    } else if (y - x == 10) {
        cout << "Difference is 10";
    } else {
        cout << "Other case";
    }
    return 0;
}

A Difference is 10

B X equals Y

C X is greater

D Other case

💡 Hint

Check each condition carefully in order.

x=10, y=20. First condition (x > y) is false. Second (x == y) is false. Third (y - x == 10) is true, so it prints "Difference is 10".