Type casting is to change the  data type of a variable according to programming need.

Type casting is done to assign values to dissimilar data type or to perform manipulation over dissimilar data type.

Type casting is of two kind :

First is performed by the system itself known as internal typecating.

Second is performed by the programmer known as explicit typecasting.

#include <stdio.h>

main() {

   int sum = 17, count = 5;
   double mean;

   mean = (double) sum / count;
   printf("Value of mean : %f\n", mean );

}

Integer Promotion

Integer promotion is the process in which value of  "smaller" than int or unsigned int are converted either to int or unsigned int.

#include <stdio.h>

main() {

   int  i = 17;
   char c = 'c'; /* ascii value is 99 */
   int sum;

   sum = i + c;
   printf("Value of sum : %d\n", sum );

}