Nested conditional statements in C++ - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of nested if-else with integer input

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

C++

#include <iostream>
using namespace std;

int main() {
    int num = 15;
    if (num > 10) {
        if (num < 20) {
            cout << "Between 11 and 19" << endl;
        } else {
            cout << "20 or more" << endl;
        }
    } else {
        cout << "10 or less" << endl;
    }
    return 0;
}

A No output

B 20 or more

C 10 or less

D Between 11 and 19

💡 Hint

Check the conditions step by step: first if num > 10, then if num < 20.

The number 15 is greater than 10 and less than 20, so the inner if condition is true, printing 'Between 11 and 19'.

❓ Predict Output

intermediate

Value of variable after nested conditions

What is the value of result after running this code?

C++

int x = 5;
int y = 10;
int result = 0;

if (x > 3) {
    if (y < 5) {
        result = 1;
    } else {
        result = 2;
    }
} else {
    result = 3;
}

A 1

B 3

C 2

D 0

💡 Hint

Check the conditions for x and y carefully.

x is 5 which is greater than 3, so the outer if is true. y is 10 which is not less than 5, so the else branch sets result to 2.

🔧 Debug

advanced

Identify the error in nested if-else code

What error will this code produce when compiled?

C++

#include <iostream>
using namespace std;

int main() {
    int a = 7;
    if (a > 5)
        if (a < 10)
            cout << "a is between 6 and 9" << endl;
        else
            cout << "a is 10 or more" << endl;
    else
        cout << "a is 5 or less" << endl;
    return 0;
}

A No error, outputs: a is between 6 and 9

B Compilation error: else without matching if

C Runtime error: segmentation fault

D No output

💡 Hint

The second 'else' has no matching 'if' because the first 'else' already pairs with the inner 'if'.

No compilation error. The 'else' pairs with the nearest unmatched 'if'. The code compiles and outputs 'a is between 6 and 9' because a=7 satisfies both conditions.

📝 Syntax

advanced

Find the syntax error in nested if-else

Which option contains the correct nested if-else syntax?

A

if (x > 0)
    if (x < 10)
        cout << "x is between 1 and 9" << endl;
    else
        cout << "x is 10 or more" << endl;

B

if (x > 0) {
    if (x < 10) {
        cout << "x is between 1 and 9" << endl;
    } else {
        cout << "x is 10 or more" << endl;
    }
}

C

if (x > 0) {
    if (x < 10) {
        cout << "x is between 1 and 9" << endl;
    } else
        cout << "x is 10 or more" << endl;
}

D

if (x > 0) 
    if (x < 10) 
        cout << "x is between 1 and 9" << endl;
    else {
        cout << "x is 10 or more" << endl;
}

💡 Hint

Check for balanced braces and proper else matching.

Option B uses braces properly for both if and else blocks, ensuring correct syntax and clear structure.

🚀 Application

expert

Determine output of complex nested conditions

What will be printed when this code runs?

C++

#include <iostream>
using namespace std;

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

A Grade B+

B Grade B

C Grade A

D Grade C or below

💡 Hint

Follow the nested conditions carefully for score 85.

Score 85 is not >= 90, so outer else runs. Then score >= 80 is true, then score >= 85 is true, so prints 'Grade B+'.