Follow The New Tutorial updates on WhatsApp, Telegram or YouTube.

1-D Array in C Language

One Dimensional or 1-D Array in C with Examples. One dimensional array is an array that has only one subscript specification that is needed to specify a particular element of an array.

An array variable must be declared before being used in a program.

An array index always starts from 0. For example, if an array variable is declared as s[10], then it ranges from 0 to 9.

1-D Array in C Language

Arrays can be single or multidimensional.

The number of subscript or index determines the dimensions of the array.

You can also say that one-dimensional or 1-D array is a structured collection of components also called array elements that can be accessed individually by specifying the position of a component with a single index value.

Declaration of 1-D Array in C Language

data_type array_name[array_size];  


int marks[5];  //Here, int is the data_type, marks are the array_name, and 5 is the array_size.

Initialization of One-Dimensional Array in C

You can initialize an array by using the index of each element.

An array can be initialized in two ways, which are as follows −

  • Compile time initialization – Also known as static initialization.
  • Runtime initialization

Example – Compile time initialization

The compile-time initialization means the array of the elements are initialized at the time the program is written or array declaration.

marks[0]=80;//initialization of array  
Initialization of One-Dimensional Array in C

Declaration with Initialization

int marks[5]={20,30,40,50,60};  //In such case, there is no requirement to define the size.

int marks1[]={20,30,40,50,60};  //Valid

Example – Run time initialization

Run time initialization means the array can be initialized at runtime. Here array elements are initialized after the compilation of the program.

main ( ){
   int a[5],i;
   printf ("enter 5 elements");
   for ( i=0; i<5; i++)
      scanf("%d", &a[i]);
   printf("elements of the array are");
   for (i=0; i<5; i++)
      printf("%d", a[i]);


int main(){      
int i=0;    
int marks[5]={20,30,40,50,60};//declaration and initialization of array    
 //traversal of array    
printf("%d \n",marks[i]);    
return 0;  

Conceptually you can think of a one-dimensional array as a row, where elements are stored one after another.

1-D Array in C Language Storage Representation