Declaring a variable with “class ” keyword vs Declaring one without “class” keyword in function signatures

Question

What is the difference between the two methods?

Sometimes when I get compile-time errors complaining that the compiler does not recognize some class types in functi

Answer 1

In this case

void recv(Client * c)

Compiler looks for declaration of Client. If it cannot find, it will give error. You can solve it by forward declaration as shown following

class Client;
void recv(Client * c)

Although I have never seen second case, but it looks like that is also declaring class Client here.