C++ Control Flow Practice

Practise if/else, switch, for and while loops, nested loops, break and continue in C++.

Beginner7 problemsUpdated October 23, 2026

Review first: if, else if and else, switch, Loops: for, while, do-while, for Loops in Depth, while and do-while, break and continue

1.Marks to grades

Beginner

For each mark in {95, 82, 67, 45, 74}, print the mark and its grade: A for 90 and above, B for 75–89, C for 60–74 and F below 60.

Show hint

Use an if / else if chain, checking from the highest grade down.

Show solution

C++

#include <iostream>
#include <vector>

int main() {
    std::vector<int> marks = {95, 82, 67, 45, 74};

    for (int m : marks) {
        char grade;
        if (m >= 90) {
            grade = 'A';
        } else if (m >= 75) {
            grade = 'B';
        } else if (m >= 60) {
            grade = 'C';
        } else {
            grade = 'F';
        }
        std::cout << m << ' ' << grade << '\n';
    }
}

Output

95 A
82 B
67 C
45 F
74 C

2.FizzBuzz

Beginner

Print the numbers 1 to 15 on one line, separated by spaces, but print Fizz for multiples of 3, Buzz for multiples of 5, and FizzBuzz for multiples of both.

Show hint

Check n % 15 == 0 first, otherwise 15 is caught by the multiple-of-3 branch.

Show solution

C++

#include <iostream>

int main() {
    for (int n = 1; n <= 15; ++n) {
        if (n % 15 == 0) {
            std::cout << "FizzBuzz";
        } else if (n % 3 == 0) {
            std::cout << "Fizz";
        } else if (n % 5 == 0) {
            std::cout << "Buzz";
        } else {
            std::cout << n;
        }
        std::cout << (n < 15 ? ' ' : '\n');
    }
}

Output

1 2 Fizz 4 Buzz Fizz 7 8 Fizz Buzz 11 Fizz 13 14 FizzBuzz

3.Digit sum and reverse

Beginner

For n = 50721, use a while loop to print the sum of its digits and the number reversed.

Show hint

Take the last digit with n % 10, then remove it with n /= 10, until n is 0. Build the reverse with reversed = reversed * 10 + digit.

Show solution

C++

#include <iostream>

int main() {
    int n = 50721;
    int sum = 0;
    int reversed = 0;

    while (n > 0) {
        int digit = n % 10;
        sum += digit;
        reversed = reversed * 10 + digit;
        n /= 10;
    }
    std::cout << sum << ' ' << reversed << '\n';
}

Output

15 12705

4.Weekday or weekend

Beginner

Days are numbered 1 (Monday) to 7 (Sunday). For each of 1, 6, 7 and 9, print weekday, weekend, or invalid using a switch.

Show hint

Group cases that share an action, and use default for anything outside 1–7.

Show solution

C++

#include <iostream>

int main() {
    for (int day : {1, 6, 7, 9}) {
        std::cout << day << ": ";
        switch (day) {
            case 1:
            case 2:
            case 3:
            case 4:
            case 5:
                std::cout << "weekday\n";
                break;
            case 6:
            case 7:
                std::cout << "weekend\n";
                break;
            default:
                std::cout << "invalid\n";
        }
    }
}

Output

1: weekday
6: weekend
7: weekend
9: invalid

5.First common multiple
Beginner
Find the first number greater than 100 that is divisible by both 7 and 11, using a loop with break.
Show hint
Loop upwards from 101 with no end condition, and break as soon as both divisions leave no remainder.
Show solution
C++
#include <iostream> int main() { int n = 101; while (true) { if (n % 7 == 0 && n % 11 == 0) { break; } ++n; } std::cout << n << '\n'; }
Output
154
A number divisible by both 7 and 11 is a multiple of 77, so the answer is 2 × 77 = 154.

6.Star pyramid

Beginner

Print a centred pyramid of stars with 4 rows: row r has 4 - r spaces followed by 2r - 1 stars.

Show hint

Use an outer loop for rows and two inner loops: one for spaces, one for stars.

Show solution

C++

#include <iostream>

int main() {
    int height = 4;
    for (int r = 1; r <= height; ++r) {
        for (int i = 0; i < height - r; ++i) std::cout << ' ';
        for (int i = 0; i < 2 * r - 1; ++i) std::cout << '*';
        std::cout << '\n';
    }
}

Output

   *
  ***
 *****
*******

7.Skip the negatives

Beginner

Add up only the positive numbers in {5, -2, 8, -7, 3}, using continue to skip the others. Print the total.

Show hint

At the top of the loop body, if (x < 0) continue;.

Show solution

C++

#include <iostream>

int main() {
    int total = 0;
    for (int x : {5, -2, 8, -7, 3}) {
        if (x < 0) continue;
        total += x;
    }
    std::cout << total << '\n';
}

Output

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