How do I check if my variable is a whole number?

I'm making a program regarding numbers but I don't know how to check if the variable is a whole number or a number with a decimal.

If someone could please tell me I would very much appreciate it.

you could floor() the number and compare it with itself. If it's the same it's an int, if not a float

or maybe better:

if number % 1 = 0 it's an int

Thanks a lot!