Different Methods of Initializing 1-D Array

Whenever we declare an array, we initialize that array directly at compile time.

Initializing 1-D Array is called as compiler time initialization if and only if we assign certain set of values to array element before executing program. i.e at compilation time.

Here we are learning the different ways of compile time initialization of an array.

Ways Of Array Initializing 1-D Array :

1. Size is Specified Directly
2. Size is Specified Indirectly

A. Method 1 : Array Size Specified Directly

In this method , we try to specify the Array Size directly.

int num[5] = {2,8,7,6,0};

In the above example we have specified the size of array as 5 directly in the initialization statement.Compiler will assign the set of values to particular element of the array.

num[0] = 2
num[1] = 8
num[2] = 7
num[3] = 6
num[4] = 0

As at the time of compilation all the elements are at Specified Position So This Initialization Scheme is Called as “Compile Time Initialization“.

Graphical Representation :

B. Method 2 : Size Specified Indirectly

In this scheme of compile time Initialization, We does not provide size to an array but instead we provide set of values to the array.

int num[] = {2,8,7,6,0};

Explanation :

1. Compiler Counts the Number Of Elements Written Inside Pair of Braces and Determines the Size of An Array.
2. After counting the number of elements inside the braces, The size of array is considered as 5 during complete execution.
3. This type of Initialization Scheme is also Called as “Compile Time Initialization“

Sample Program

#include <stdio.h>
int main()
{
int num[] = {2,8,7,6,0};
int i;
for(i=0;i<5;i++) {
    printf("\nArray Element num[%d] : %d",i+1,num[i]);
}
return 0;
}

Output :

Array Element num[1] : 2
Array Element num[2] : 8
Array Element num[3] : 7
Array Element num[4] : 6
Array Element num[5] : 0

In this tutorial we will be learning the C Array Declaration. A programmer need to specify the type of the elements and the number of elements required by an array.

C Array Declaration

Array has to be declared before using it in C Program. Array is nothing but the collection of elements of similar data types.

Syntax

<data_type>  array_name  [size1][size2].....[sizen];

Array declaration requirement

What does C Array Declaration tells to Compiler ?

1. Type of the Array
2. Name of the Array
3. Number of Dimension
4. Number of Elements in Each Dimension

Examples of C Array Declaration

Examples : Declaring 1D array

// Array of 10 integer roll numbers  
int roll[10]

In the above example we are declaring the integer array of size 10. Array is single dimensional and have

Examples : Declaring 2D array

// 2-D Array
char name[80][20];

In the above example we are declaring 2D array which has 2 dimensions. First dimension will refer the row and 2nd dimension will refer the column.

Examples : Declaring 3D array

// 3-D Array
char name[80][20][40];

Above declaration tells compiler following things -