void
is only used in the function declaration. When you call a function with void
return type, just call it without using void
.
Use
void testerForVoid();
to declare a function that returnsvoid
, as the forward declared in your case.Use
testerForVoid();
to call the function.
In you example, for option#2, it tends to declare the function again, which has already been forward declared. No real function all is conducted.