Iterate Over Arrays using Loops in C

In C, we can iterate over an array using loops such as for, while, and do-while. Looping through an array allows us to access each element and perform operations like printing, modifying, or computing values. In this tutorial, we will explore different ways to iterate over an array with detailed explanations and examples.

Examples to Iterate Over Arrays

1. Iterating Over an Array Using a for Loop

In this example, we will use a for loop to traverse an integer array and print all its elements.

main.c

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#include <stdio.h>

int main() {
    int numbers[] = {10, 20, 30, 40, 50};
    int size = sizeof(numbers) / sizeof(numbers[0]);

    // Loop through the array using for loop
    for (int i = 0; i < size; i++) {
        printf("%d ", numbers[i]);
    }

    return 0;
}

Explanation:

  1. We declare an integer array numbers[] containing 5 elements.
  2. We calculate the size of the array using sizeof(numbers) / sizeof(numbers[0]), which determines the number of elements.
  3. We use a for loop where i starts at 0 and iterates up to size - 1.
  4. Inside the loop, we use printf() to print each array element.

Output:

10 20 30 40 50

2. Iterating Over an Array Using a while Loop

In this example, we will use a while loop to iterate through an array and print its elements.

main.c

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#include <stdio.h>

int main() {
    int numbers[] = {5, 15, 25, 35, 45};
    int size = sizeof(numbers) / sizeof(numbers[0]);
    int i = 0;

    // Loop through the array using while loop
    while (i < size) {
        printf("%d ", numbers[i]);
        i++;
    }

    return 0;
}

Explanation:

  1. We declare an integer array numbers[] with 5 elements.
  2. We calculate the number of elements using sizeof().
  3. We initialize i to 0 before the while loop.
  4. The while loop runs as long as i is less than size.
  5. Inside the loop, we print the element at index i and then increment i.

Output:

5 15 25 35 45

3. Iterating Over an Array Using a do-while Loop

In this example, we will use a do-while loop to iterate through an array and print its elements.

main.c

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#include <stdio.h>

int main() {
    int numbers[] = {2, 4, 6, 8, 10};
    int size = sizeof(numbers) / sizeof(numbers[0]);
    int i = 0;

    // Loop through the array using do-while loop
    do {
        printf("%d ", numbers[i]);
        i++;
    } while (i < size);

    return 0;
}

Explanation:

  1. We declare an integer array numbers[] with 5 elements.
  2. We determine the size using sizeof().
  3. We initialize i to 0 before the do-while loop.
  4. The loop executes at least once, printing the element at i, then increments i.
  5. The condition i < size is checked after each iteration.

Output:

2 4 6 8 10

Conclusion

In this tutorial, we explored different ways to iterate over arrays using loops in C:

  1. for Loop: Best for iterating when the number of elements is known.
  2. while Loop: Useful when iteration depends on a condition.
  3. do-while Loop: Ensures at least one iteration.