Arrays in C language

An array in C language is defined as a finite and ordered collection of similar data types which get stored in contiguous memory locations.

• finite: The range of data must be defined.
• ordered: The data must be stored in some order and C compiler store data as continuous memory addresses.

Important points to remember:

• Arrays are the derived data type in C which can store the primitive type of data such as int, char, double, float, etc.
• We can access any element randomly in an array by using its index number.
• The index number starts from zero (0) and increment by one till size - 1.
• Each element of an array is of same data type and carries the same size. For example, if data type is int then each element is of 4 bytes.

Syntax

The following is the syntax for declaring an array.

type arrayName [ arraySize ];

where

• arraySize must be an integer and must be greater than zero.
• type is a valid C data type.

This is called a single-dimensional array.

Example

int arr[10];  // create an array with 10 integer elements

Declaration with initialization

We can also initialize an array during its declaration.

int evens[5] = {2, 4, 6, 8, 10};  // array of 5 even numbers

Access Array Elements

We can access any element of an array by its index number.

Syntax:

arrayName [ indexNumber ];

For example, to access elements from evens array as defined above, we can use following:

#include <stdio.h>

int main() {
  int i, evens[5] = {2, 4, 6, 8, 10};

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

  return 0;
}

// output
evens[0] = 2
evens[1] = 4
evens[2] = 6
evens[3] = 8
evens[4] = 10