Function pointer,

Function pointer,

1. First, let's talk about functions.

In fact, each function name is the function entry address, as shown in:

 

0x4013B0 is the entry address of the func () function. As you can see, func AND & func have the same address.

2. Use the function pointer to point to the above func () function.

Instance 1 is as follows:

#include "stdio.h"

int func (int x)
{
    return x;
}

int main ()
{
   int (* FP) (int); // Define FP function pointer

   FP = func; // FP points to the address of func

   printf ("% d \ n", FP (1));

   printf ("% p,% p \ n", FP, func);
 
   return 0;
}

Output result:

1 // call func () function
004013B0,004013B0

2) When typedef is used, the function pointer uses the following:

#include "stdio.h"

int func (int x)
{
    return x;
}

typedef int (* FP) (int); // Use declared function pointer type FP

int main ()
{
   FP a; // Define function pointer a via FP
  
   a = func; // a points to the address of func

   printf ("% d \ n", a (1));

   printf ("% p,% p \ n", a, func);

   return 0;
}