typecasting long to int and short in C

Question

long x = <some value>
int y = <some value>

I want to subtract y from x , which of the following will give me different or same results

 x = (int)x - y;

 x = x-y

 x = short(x) - short(y)

Answer 1

The type long is "bigger" than int . Smaller types can be automatically casted to bigger types. So, this code:

someLongNumber + someIntNumber

is basically equal to

someLongNumber + (long)someIntNumber

So the output will be long . You don't have to cast if you want to place the result in x . However, if you want to place it in y , you must cast the x operand to int ( (int)x ), or the whole operation ( (int)(x - y) ).