What is the significance of 0.0f when initializing (in C)?

Question

I've seen code where people initialize float variables like this:

float num = 0.0f;

Is there a significant difference between this and just doing the following below?

float num = 0; 

Thanks.. :)

Answer 1

float x = 0 has an implicit typecast from int to float.
float x = 0.0f does not have such a typecast.
float x = 0.0 has an implicit typecast from double to float.

Depending on the compiler, implicit typecast can require the compiler to generate extra code.