指向c中函数的指针

Question

Please look at the code following:-

 #include <stdio.h>
 int sum ( int b, int a){
 return (a+b);
  }
 int main(){
 int (* funptr)( int , int ) = sum;
 int a = ( * funptr )( 4,5);
 int b = funptr (4,5);
 printf("%d\n%d",a,b);
 return 1;
 }

Is there any difference between the two function calling via pointer,one is

int a = ( * funptr )( 4,5);

and another is

int b = funptr (4,5);

As i have compiled this code and result is same in both the cases.Is this means that these are equivalent?

Answer 1

Due to historic differences how to take the address of a function, you can apply address of and dereference any time you want to a function name, without any effect whatsoever.

Also, dereferencing a function pointer has no effect at all.

So, yes, your examples are equivalent.

Answer 2

In case of function pointer:

Function Pointer is very flexible to use.. You can put value into it with or without the & operator, and call the stored function through pointer with or without * operator.

eg,

int (* funptr)( int , int ) = sum;   // or int (* funptr)( int , int ) = ∑
int a = ( * funptr )( 4,5);          // or int a = funptr( 4,5);

Hope it helped...