Array traversal in C - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of array traversal with pointer arithmetic

What is the output of this C program?

C

#include <stdio.h>

int main() {
    int arr[] = {10, 20, 30, 40, 50};
    int *p = arr;
    for (int i = 0; i < 5; i++) {
        printf("%d ", *(p + i));
    }
    return 0;
}

A 10 20 30 40 50

B 50 40 30 20 10

C 10 20 30 40 0

D Compilation error

💡 Hint

Remember that pointer arithmetic moves through the array elements in order.

The pointer p points to the first element of the array. Adding i moves it to the i-th element. So *(p + i) accesses each element in order, printing 10 20 30 40 50.

❓ Predict Output

intermediate

Output of array traversal with index and pointer

What will be printed by this C code?

C

#include <stdio.h>

int main() {
    int arr[3] = {1, 2, 3};
    int *p = arr;
    for (int i = 0; i < 3; i++) {
        printf("%d ", p[i]);
    }
    return 0;
}

A 1 2 3

B 3 2 1

C 0 0 0

D Runtime error

💡 Hint

Pointer p points to the first element, so p[i] accesses elements by index.

Using p[i] is equivalent to *(p + i), so it prints the array elements in order: 1 2 3.

❓ Predict Output

advanced

Output of nested array traversal

What is the output of this C program?

C

#include <stdio.h>

int main() {
    int matrix[2][3] = {{1, 2, 3}, {4, 5, 6}};
    for (int i = 0; i < 2; i++) {
        for (int j = 0; j < 3; j++) {
            printf("%d ", matrix[i][j]);
        }
    }
    return 0;
}

A 1 4 2 5 3 6

B 1 2 3 4 5 6

C 6 5 4 3 2 1

D Compilation error

💡 Hint

The outer loop goes through rows, inner loop through columns.

The code prints each element row by row: first row 1 2 3, then second row 4 5 6.

❓ Predict Output

advanced

Output of pointer traversal with increment

What does this C program print?

C

#include <stdio.h>

int main() {
    int arr[] = {7, 8, 9};
    int *p = arr;
    for (int i = 0; i < 3; i++) {
        printf("%d ", *p++);
    }
    return 0;
}

A 7 7 7

B 9 8 7

C 7 8 9

D Compilation error

💡 Hint

The *p++ means print value at p, then move p to next element.

The pointer p starts at arr[0]. Each loop prints *p then increments p, so prints 7 8 9.

❓ Predict Output

expert

Value of variable after complex array traversal

What is the value of variable sum after running this C code?

C

#include <stdio.h>

int main() {
    int arr[4] = {2, 4, 6, 8};
    int *p = arr + 1;
    int sum = 0;
    for (int i = 0; i < 3; i++) {
        sum += *(p++);
    }
    printf("%d", sum);
    return 0;
}

A 14

B Runtime error

C 20

D 18

💡 Hint

Pointer p starts at arr[1], sum adds three elements from there.

p points to arr[1] = 4, then 6, then 8. Sum = 4 + 6 + 8 = 18.