Array in C Language

 C Array is a collection of variables belongings to the same data type. You can store group of data of same data type in an array.

• Array might be belonging to any of the data types
• Array size must be a constant value.
• Always, Contiguous (adjacent) memory locations are used to store array elements in memory.
• It is a best practice to initialize an array to zero or null while declaring, if we don’t assign any values to array.

Example for Arrays in C Language:

• int a[10];       // integer array
• char b[10];   // character array   i.e. string

Types of arrays in C Language:

There are 2 types of C arrays. They are,

1. One dimensional array
2. Multi dimensional array
   • Two dimensional array
   • Three dimensional array, four dimensional array etc…

1. One dimensional array in C language:

• Syntax : data-type arr_name[array_size];

Array declaration	Array initialization	Accessing array
Syntax:  data_type arr_name [arr_size];	data_type arr_name [arr_size]= (value1, value2, value3,….);	arr_name[index];
int age [5];	int age[5]={0, 1, 2, 3, 4, 5};	age[0];_/*0_is_accessed*/ age[1];_/*1_is_accessed*/ age[2];_/*2_is_accessed*/
char str[10];	char str[10]={‘H’,‘a’,‘i’}; (or) char str[0] = ‘H’; char str[1] = ‘a’; char str[2] = ‘i;	str[0];_/*H is accessed*/ str[1];  /*a is accessed*/ str[2];  /* i is accessed*/

Example program for one dimensional array in C language:

C

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#include<stdio.h>   int main() {     int i;     int arr[5] = {10,20,30,40,50};       // declaring and Initializing array in C     //To initialize all array elements to 0, use int arr[5]={0};     /* Above array can be initialized as below also        arr[0] = 10;        arr[1] = 20;        arr[2] = 30;        arr[3] = 40;        arr[4] = 50;     */     for (i=0;i<5;i++)     {         // Accessing each variable         printf("value of arr[%d] is %d \n", i, arr[i]);     } }

Output:

value of arr[0] is 10 value of arr[1] is 20 value of arr[2] is 30 value of arr[3] is 40 value of arr[4] is 50

2. Two dimensional array in C language:

• Two dimensional array is nothing but array of array.
• syntax : data_type array_name[num_of_rows][num_of_column]

S.no	Array declaration	Array initialization	Accessing array
1	Syntax:  data_type arr_name [num_of_rows][num_of_column];	data_type arr_name[2][2] = {{0,0},{0,1},{1,0},{1,1}};	arr_name[index];
2	Example: int arr[2][2];	int arr[2][2] = {1,2, 3, 4};	arr [0] [0] = 1;  arr [0] ]1] = 2; arr [1][0]  = 3; arr [1] [1] = 4;

Example program for two dimensional array in C language:

C

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#include<stdio.h> int main() {     int i,j;     // declaring and Initializing array     int arr[2][2] = {10,20,30,40};     /* Above array can be initialized as below also        arr[0][0] = 10;   // Initializing array        arr[0][1] = 20;        arr[1][0] = 30;        arr[1][1] = 40;     */     for (i=0;i<2;i++)     {        for (j=0;j<2;j++)        {           // Accessing variables           printf("value of arr[%d] [%d] : %d\n",i,j,arr[i][j]);        }     } }

Output:

value of arr[0] [0] is 10 value of arr[0] [1] is 20 value of arr[1] [0] is 30 value of arr[1] [1] is 40

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