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How to Initialize Array to 0 in C?

Last Updated : 17 Jun, 2024
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Initializing an array to zero is a common practice in programming to ensure that all elements start with a known value. In C, there are several ways to initialize an array to zero. In this article, we will explore different methods to do so.

Initialize Array to 0 in C

There are mainly two ways to initialize array in C and we can initialize arrays to zero both at the time of declaration and after declaration.

  1. With Declaration using Initializer List
  2. After Declaration using Loops or memset()

Array Initialization with Declaration

The simplest way to initialize an array to zero is at the time of declaration by using an initializer list or by setting the first element to zero.

C Program to Initialize Array to 0

C 
// C program to initialize an array to zero at declaration
#include <stdio.h>

int main()
{
    // Using an initializer list
    int arr1[5] = { 0 };

    // Setting the first element to zero
    int arr2[5] = {
        0
    }; // All elements are implicitly initialized to zero

    // Print the arrays
    for (int i = 0; i < 5; i++) {
        printf("%d ", arr1[i]);
    }
    printf("\n");

    for (int i = 0; i < 5; i++) {
        printf("%d ", arr2[i]);
    }
    printf("\n");

    return 0;
}

Output
0 0 0 0 0 
0 0 0 0 0

After Declaration Array Initialization

If you need to initialize an array to zero after it has been declared, you can use a loop or the memset() function from the C standard library.

C 
// C program to initialize an array to zero after
// declaration
#include <stdio.h>
#include <string.h>

int main()
{
    int arr[5];

    // Using a loop
    for (int i = 0; i < 5; i++) {
        arr[i] = 0;
    }

    // Using memset()
    memset(arr, 0, sizeof(arr));

    // Print the array
    for (int i = 0; i < 5; i++) {
        printf("%d ", arr[i]);
    }
    printf("\n");

    return 0;
}

Output
0 0 0 0 0



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