Why loops are needed in C - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

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

C

#include <stdio.h>

int main() {
    int i = 1;
    while ([1] <= 5) {
        printf("%d\n", i);
        i++;
    }
    return 0;
}

Drag options to blanks, or click blank then click option'

Ai

B5

C0

D10

Attempts:

3 left

💡 Hint

Common Mistakes

Using a fixed number instead of the loop variable in the condition.

Not using the variable that changes inside the loop.

The variable i is used to control the loop and print numbers from 1 to 5.

2fill in blank

medium

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

C

#include <stdio.h>

int main() {
    int sum = 0;
    for (int i = 1; i [1] 10; i++) {
        sum += i;
    }
    printf("Sum is %d\n", sum);
    return 0;
}

Drag options to blanks, or click blank then click option'

A<=

B>

C<

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using < instead of <=, which stops at 9.

Using == which only runs once.

The loop should include 10, so the condition uses <= to go up to 10.

3fill in blank

hard

Fix the error in the loop condition to print numbers from 0 to 4.

C

#include <stdio.h>

int main() {
    int count = 0;
    while (count [1] 5) {
        printf("%d\n", count);
        count++;
    }
    return 0;
}

Drag options to blanks, or click blank then click option'

A==

B>=

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using > or >= which causes the loop not to run.

Using == which runs only once.

The loop should run while count is less than 5 to print 0 to 4.

4fill in blank

hard

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

C

#include <stdio.h>

int main() {
    for (int num = [1]; num [2] 10; num += 2) {
        printf("%d\n", num);
    }
    return 0;
}

Drag options to blanks, or click blank then click option'

A2

B1

C<=

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Starting from 1 instead of 2.

Using > instead of <= which skips printing 10.

The loop starts at 2 and runs while num is less than or equal to 10 to print even numbers.

5fill in blank

hard

Fill all three blanks to create a loop that prints numbers from 5 down to 1.

C

#include <stdio.h>

int main() {
    for (int i = [1]; i [2] 1; i[3]) {
        printf("%d\n", i);
    }
    return 0;
}

Drag options to blanks, or click blank then click option'

A5

B>=

C--

D++

Attempts:

3 left

💡 Hint

Common Mistakes

Using ++ instead of -- which counts up instead of down.

Using < instead of >= which causes the loop to not run.

The loop starts at 5, runs while i is greater than or equal to 1, and decreases i by 1 each time.