Ellipses Operator (. . .)

This operator is used to represent various number of parameters involve. This is mainly used in function arguments , when the number of arguments is not known.

Ex -
int foo(int i, int j, . . .);

But we can use ellipses operator in other part of coding also.

In switch case

 main()  
 {  
     --------  
     --------  
     switch(3)  
     {  
         case 1 ... 4:  
           printf("Option is between 1 to 4);  
           break;  
         case 5 ... 9:  
           printf("Option is between 5 to 9);  
           break;  
     }  
 }  

In array

Ellipses operator used in array initialization also. Using this operator we can partially initialize our arrays.

Ex - 

 main()  
 {  
      int arr[] = { [0 ... 4] 4, [5 ... 9] 5};  
      printf("arr[0] %d\n", arr[0]);  
      printf("arr[6] %d\n", arr[6]);  
 }  
 o/p -   
 arr[0] 4  
 arr[6] 5  
 Partially initialize the array   
 main()  
 {  
     int arr[10] = { [3]5, [1] = 4, [4] 3, [0] = 0 };  
      printf("arr[0] %d\n", arr[0]);  
      printf("arr[3] %d\n", arr[3]);  
      printf("arr[4] %d\n", arr[4]);  
 }  
 o/p -   
 arr[0] 0  
 arr[3] 5  
 arr[4] 3