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This article explains how to initialize an array to 0 in C language.

The declaration of an array in C language is as follows.

char ZEROARRAY[1024];

It becomes all zeros at runtime in the global scope. If it is a local array, there is a simple way. The declaration and initialization of the array is as follows.

char ZEROARRAY[1024] = {0};

If an array is partially initialized, the uninitialized elements will receive values ​​of the relevant data type 0. The compiler will fill the unwritten elements with zeros.

If no initializer is specified, then an object with static storage is initialized to 0, as declared below.

static int myArray[10]; 

If the initializer list is empty or 0 is specified in the initializer list, the array will be initialized to 0. The declaration is as follows:

int number[5] =  { };
int number[5] =  { 0 };

The simplest way to initialize an array is to iterate over all elements and set each one to 0.

#include <stdio.h>

int main(void)
{

    int numberArray[10], counter;

    for(counter = 0 ; counter < 5 ; counter++)
    {
        numberArray[counter] = 0;
    }
    printf("Array elements are:\n");
    for(counter=0; counter<5; counter++)
    {
        printf("%d",numberArray[counter]);
    }
    return 0;
}

Output:

Array elements are:
00000

Using C library functionsmemset()

The function memset()is string.ha library function in . It is used to fill a memory block with a specific value.

memset()The syntax of the function is as follows.

void *memset(void *pointerVariable, int anyValue, size_t numberOfBytes);

in,

• pointerVariableis a pointer variable pointing to the memory block to be filled.
• anyValueIs the value to be set. This is an integer value, but the function uses the unsigned char conversion of this value to fill the memory block.
• numberOfBytesis the number of bytes of the value to be set.

The function returns a pointerVariablepointer to the memory area.

The complete procedure is as follows.

#include <stdio.h>
#include <string.h>

void printArrayvalues(int anyArray[], int anyNumber)
{
    int index;
    for (index=0; index<anyNumber; index++)
        printf("%d ", anyArray[index]);
}

int main(void)
{
    int number = 10;
    int arrayValues[number];
    
    memset(arrayValues, 0, number*sizeof(arrayValues[0]));
    printf("Array after memset()\n");

    printArrayvalues(arrayValues, number);

    return 0;
}

Output:

Array after memset()
0 0 0 0 0 0 0 0 0 0 

Initializing an array in C to 0a value other than

Use gccto initialize an array to 0a value other than , as shown below.

int myArrayValues[1024] = { [ 0 ... 1023 ] = -1 };

Each member of an array can be explicitly initialized by omitting the dimension. The declaration is as follows.

int myArrayValues[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };

The compiler will infer the dimensions from the initializer list, and for multidimensional arrays only the outermost dimension can be omitted.

int myPoints[][3] = { { 1, 2, 3 }, { 4, 5, 6 }, { 7, 8, 9} };