Loop execution flow in C++ - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of nested loops with break

What is the output of this C++ code snippet?

C++

#include <iostream>
int main() {
    for (int i = 1; i <= 3; ++i) {
        for (int j = 1; j <= 3; ++j) {
            if (j == 2) break;
            std::cout << i << j << " ";
        }
    }
    return 0;
}

A 11 12 13 21 22 23 31 32 33

B 11 12 21 22 31 32

C 11 21 31

D 11 21 22 31 32

💡 Hint

The inner loop breaks when j equals 2, so only j=1 prints per outer loop iteration.

The inner loop prints when j=1, then breaks at j=2, so for each i (1 to 3), only i1 is printed.

❓ Predict Output

intermediate

While loop with continue behavior

What is the output of this C++ code?

C++

#include <iostream>
int main() {
    int i = 0;
    while (i < 5) {
        i++;
        if (i == 3) continue;
        std::cout << i << " ";
    }
    return 0;
}

A 1 2 4 5

B 1 2 3 4 5

C 1 2 3 4

D 2 3 4 5

💡 Hint

When i equals 3, the continue skips the print for that iteration.

The loop increments i first, then skips printing when i==3, so output excludes 3.

❓ Predict Output

advanced

For loop with multiple increments

What is the output of this C++ code snippet?

C++

#include <iostream>
int main() {
    for (int i = 0; i < 5; i += 2) {
        std::cout << i << " ";
        i++;
    }
    return 0;
}

A 0 2 3 4

B 0 2 4

C 0 1 3

D 0 3

💡 Hint

The loop increments i twice each iteration: once in the body and once in the for statement.

i starts at 0, prints 0, increments to 1 inside loop, then increments by 2 to 3 in for, prints 3, increments to 4 inside loop, then increments by 2 to 6 in for, loop ends.

❓ Predict Output

advanced

Do-while loop execution count

How many times does the loop body execute in this C++ code?

C++

#include <iostream>
int main() {
    int count = 0;
    int i = 5;
    do {
        count++;
        i++;
    } while (i < 5);
    std::cout << count;
    return 0;
}

A 0

B 1

C 5

D Infinite loop

💡 Hint

A do-while loop runs the body at least once before checking the condition.

The loop runs once, increments i from 5 to 6, then checks condition i<5 which is false, so it stops after one iteration.

❓ Predict Output

expert

Complex nested loop with continue and break

What is the output of this C++ program?

C++

#include <iostream>
int main() {
    for (int i = 1; i <= 3; ++i) {
        for (int j = 1; j <= 3; ++j) {
            if (i == j) continue;
            if (i + j == 4) break;
            std::cout << i << j << " ";
        }
    }
    return 0;
}

A 12 13 21 31

B 12 21 31

C 12 13 21 23 31

D 11 22 33

💡 Hint

Pay attention to when continue skips printing and when break stops the inner loop.

For i=1: j=1 skipped (continue), j=2 prints 12, j=3 prints 13; for i=2: j=1 prints 21, j=2 skipped (continue), j=3 breaks (2+3=5, no break, but condition is i+j==4, so break at j=2 since 2+2=4), so j=3 not reached; for i=3: j=1 prints 31, j=2 breaks (3+2=5 no), j=3 skipped (continue). So output is 12 13 21 31.