While loop in C++ - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print numbers from 1 to 5 using a while loop.

C++

#include <iostream>

int main() {
    int i = 1;
    while ([1]) {
        std::cout << i << std::endl;
        i++;
    }
    return 0;
}

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Ai <= 5

Bi < 1

Ci == 0

Di > 5

Attempts:

3 left

💡 Hint

Common Mistakes

Using a condition that never becomes false, causing an infinite loop.

Using a condition that is false from the start, so the loop never runs.

The condition i <= 5 ensures the loop runs while i is from 1 to 5.

2fill in blank

medium

Complete the code to sum numbers from 1 to 10 using a while loop.

C++

#include <iostream>

int main() {
    int sum = 0;
    int num = 1;
    while ([1]) {
        sum += num;
        num++;
    }
    std::cout << sum << std::endl;
    return 0;
}

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Anum < 10

Bnum == 10

Cnum <= 10

Dnum > 10

Attempts:

3 left

💡 Hint

Common Mistakes

Using num < 10 which excludes 10 from the sum.

Using a condition that never ends.

The condition num <= 10 makes sure numbers 1 through 10 are added.

3fill in blank

hard

Fix the error in the while loop condition to count down from 5 to 1.

C++

#include <iostream>

int main() {
    int count = 5;
    while ([1]) {
        std::cout << count << std::endl;
        count--;
    }
    return 0;
}

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Acount > 5

Bcount >= 1

Ccount == 0

Dcount < 1

Attempts:

3 left

💡 Hint

Common Mistakes

Using a condition that never becomes false.

Using a condition that is false from the start.

The condition count >= 1 keeps the loop running while counting down from 5 to 1.

4fill in blank

hard

Fill both blanks to create a while loop that prints even numbers from 2 to 10.

C++

#include <iostream>

int main() {
    int num = [1];
    while (num [2] 10) {
        std::cout << num << std::endl;
        num += 2;
    }
    return 0;
}

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A2

B<=

C<

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Starting at 1 instead of 2.

Using < which excludes 10.

Start at 2 and continue while num is less than or equal to 10 to print even numbers.

5fill in blank

hard

Fill all three blanks to create a while loop that builds a dictionary mapping numbers 1 to 5 to their squares.

C++

#include <iostream>
#include <map>

int main() {
    std::map<int, int> squares;
    int i = [1];
    while (i [2] 5) {
        squares[[3]] = i * i;
        i++;
    }
    for (const auto& [key, value] : squares) {
        std::cout << key << ": " << value << std::endl;
    }
    return 0;
}

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A1

B<=

Ci

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Starting at 0 instead of 1.

Using < which excludes 5.

Using a wrong key for the map.

Start i at 1, loop while i is less than or equal to 5, and use i as the key in the map.