Consider the following function:

int foo()
{
    return 5;
}

The syntax for creating a function pointer that takes no arguments and returns an integer is following:

int (*fptr)();

Typedefs can be used to make pointers to functions look more like regular variables:

typedef int (*fptr)();

This defines a typedef called “fptr” that is a pointer to a function that takes no arguments and returns int. Now instead of doing this:

bool validate(int x, int (*fcnPtr)());

You can do this:

bool validate(int nX, fptr f)

More information: Function Pointers