why sizeof(13.33) is 8 bytes?

Question

When I give sizeof(a), where a=13.33, a float variable, the size is 4 bytes. But if i give sizeof(13.33) directly, the size is 8 bytes

Answer 1

The type and size of your variable are fine. It's just that the compiler has some default types for literals, those constant values hard-coded in your program.

If you request sizeof(1), you'll get sizeof(int). If you request sizeof(2.5), you'll get sizeof(double). Those would clearly fit into a char and a float respectively, but the compiler has default types for your literals and will treat them as such until assignment.

You can override this default behaviour, though. For example:

2.5 // as you didn't specify anything, the compiler will take it for a double.
2.5f // ah ha! you're specifying this literal to be float

Cheers!