Array traversal in C - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print all elements of the array.

C

#include <stdio.h>

int main() {
    int arr[] = {1, 2, 3, 4, 5};
    int n = 5;
    for (int i = 0; i < n; [1]) {
        printf("%d\n", arr[i]);
    }
    return 0;
}

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

Ai--

B++i

Ci++

Di+=2

Attempts:

3 left

💡 Hint

Common Mistakes

Using decrement operator causes the loop to never run or run incorrectly.

Skipping elements by increasing by 2 misses some array elements.

The loop variable i must increase by 1 each time to traverse the array from start to end.

2fill in blank

medium

Complete the code to sum all elements in the array.

C

#include <stdio.h>

int main() {
    int arr[] = {10, 20, 30, 40};
    int n = 4;
    int sum = 0;
    for (int i = 0; i < n; i++) {
        sum [1] arr[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 subtraction or multiplication operators changes the sum incorrectly.

Using division operator causes runtime errors or wrong results.

The += operator adds the current array element to the sum.

3fill in blank

hard

Fix the error in the loop condition to avoid accessing out of array bounds.

C

#include <stdio.h>

int main() {
    int arr[] = {5, 10, 15};
    int n = 3;
    for (int i = 0; i [1] n; i++) {
        printf("%d\n", arr[i]);
    }
    return 0;
}

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

A>

B<

C>=

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using <= causes the loop to access arr[n], which is out of bounds.

Using > or >= causes the loop to never run or run incorrectly.

The loop should run while i is less than n to avoid accessing beyond the last element.

4fill in blank

hard

Fill both blanks to create a loop that prints only even numbers from the array.

C

#include <stdio.h>

int main() {
    int arr[] = {1, 2, 3, 4, 5, 6};
    int n = 6;
    for (int i = 0; i < n; i++) {
        if (arr[i] [1] 2 [2] 0) {
            printf("%d\n", arr[i]);
        }
    }
    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 '==' selects odd numbers instead of even.

Using '>' does not correctly check for even numbers.

The modulus operator % checks the remainder when dividing by 2. If it equals 0, the number is even.

5fill in blank

hard

Fill all three blanks to create a dictionary-like structure using arrays and print keys with values greater than 10.

C

#include <stdio.h>

int main() {
    char *keys[] = {"a", "b", "c", "d"};
    int values[] = {5, 15, 8, 20};
    int n = 4;
    for (int [1] = 0; [2] < n; [3]++) {
        if (values[i] > 10) {
            printf("%s: %d\n", keys[i], values[i]);
        }
    }
    return 0;
}

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

Ai

Dj

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names causes compilation errors.

Using a variable not declared causes errors.

The loop variable i is used consistently to index both arrays.