Understanding typedefs for function pointers in C

Question

I have always been a bit stumped when I read other peoples\' code which had typedefs for pointers to functions with arguments. I recall that it took me a while to get around

Answer 1

int add(int a, int b)
{
  return (a+b);
}
int minus(int a, int b)
{
  return (a-b);
}

typedef int (*math_func)(int, int); //declaration of function pointer

int main()
{
  math_func addition = add;  //typedef assigns a new variable i.e. "addition" to original function "add"
  math_func substract = minus; //typedef assigns a new variable i.e. "substract" to original function "minus"

  int c = addition(11, 11);   //calling function via new variable
  printf("%d\n",c);
  c = substract(11, 5);   //calling function via new variable
  printf("%d",c);
  return 0;
}

Output of this is :

22

6

Note that, same math_func definer has been used for the declaring both the function.

Same approach of typedef may be used for extern struct.(using sturuct in other file.)