An array is a collection of elements of the same type stored in contiguous memory locations. An array declaration specifies the element type, array name, and number of elements.

#include <stdio.h>

int main(void)
{
    int numbers[5];

    numbers[0] = 10;
    numbers[1] = 20;
    numbers[2] = 30;
    numbers[3] = 40;
    numbers[4] = 50;

    printf("%d\n", numbers[0]);
    printf("%d\n", numbers[2]);
    printf("%d\n", numbers[4]);

    return 0;
}

Example Output #

10
30
50

Explanation #

The declaration:

int numbers[5];

declares an array named numbers that contains five elements of type int.

Array indexing starts at 0. Therefore, an array containing five elements has valid indices from 0 through 4.

An individual element is accessed using the array name followed by an index enclosed in square brackets.

numbers[2] = 30;

This statement assigns 30 to the element at index 2.

Array Declaration Syntax #

data_type array_name[array_size];

Arrays can contain different element types by declaring separate arrays:

int ages[5];
float temperatures[10];
char letters[4];
double measurements[8];

For an ordinary array declaration, the size must be a valid array bound. A fixed-size array can use an integer constant expression:

#define SIZE 5

int numbers[SIZE];

The elements of a local array declared without an initializer have indeterminate values. They should be assigned valid values before those values are read.