Array is a collection of similar data which is stored in continuous memory addresses. Array values can be fetched using index.

Index starts from 0 to size-1.

Arrays can be one-dimensional or multi-dimensional in C language. The more popular and frequently used arrays are one-dimensional and two-dimensional arrays.

Arrays store the collection of data sequentially in memory and they must share same data type.

How to declare an array?

One dimentional Array:

data-type array-name[size];

Two dimensional array:

data-type array-name[size][size];

Examples

One dimentional Array:

int a[5];

Two dimentional Array:

int a[2][3];
int b[][3]; // is also valid

How to initialize arrays

One dimentional Array:

int a[5] = {1,2,3,4,5};

Two dimentional Array:

int a[2][3] = {
                {1,2,3},
                {4,5,6}
              };

How to access array elements

Array elements can be accessed by using indices. Array indices starts from 0 and Array[n-1] can be used to access nth element of an array.

Examples

One dimentional array:

#include <stdio.h>
int main()
{
    int arr[5] = {1,2,3,4,5};
    int n = sizeof(arr)/sizeof(arr[0]); // gives length of an array
    printf("Length of the array:%d", n);
    printf("\nfirst element: %d", arr[0]); // prints first element of the array
    printf("\nlast element: %d", arr[n-1]); // prints last element of the array
}

Check result here

Two dimentional array:

#include <stdio.h>
int main()
{
  int a[2][3] = {
                {1,2,3},
                {4,5,6}
              };
  for(int i=0; i<2; i++) // iterates for each row
  {
    for(int j=0; j<3; j++) // iterates for each column
    {
        printf("%d ", a[i][j]);
    }
        printf("\n");
}   
}

Check result here

Summary

• Array is a collection of homogeneous data.
• Arrays stores data sequentially in memory.
• Arrays are finite.