Initialization of Single Dimensional Array

Single Dimensional Arrays in C can be initialized in the following way:

Method 1:

int rollnum[6]={5,3,32,9,2,10};

By this way, you specify the size of the array and initialize the values.

Method 2:

int rollnum[]={5,3,32,9,2,10};

You can even assign values to the array, without initializing the size of the array.

Method 3:

int rollnum[5];
int i;
for( i=0;i<5;i++ )
{
   rollnum[i] = i;
}

You can initialize the arrays this way too.

Accessing Array Elements

In C programming, you can access and operate arrays like variables in C. To access i'th element in the array you need to write as <array name>[i-1]. Since the array index starts from 0.

For example:

scanf("%d",&rollNum[3]);
/* statement to insert value in the forth element of array rollNum[]. */

scanf("%d",&rollNum[i]);
/* Statement to insert value in (i+1)th element of array rollNum[]. */
/* Because, the first element of array is rollNum[0], second is rollNum[1], ith is rollNum[i-1] and (i+1)th is rollNum[i]. */

printf("%d",rollNum[0]);
/* statement to print first element of an array. */

printf("%d",rollNum[i]);
/* statement to print (i+1)th element of an array. */

One thing you should remember is that, when you have declared roll_Number[6] array of size 6, your valid access to the array is only from 0 to 5. If you try to access any invalid index like 8, 10 etc. compiler do not throw any error, it will be throw a runtime error. Usually a program crash due to invalid memory manipulation i.e. it would cause a segmentation fault.