#include <stdio.h>
// A normal function with an int parameter
// and void return type
void fun(int a)
{
printf("Value of a is %d\n", a);
}
int main()
{
// fun_ptr is a pointer to function fun()
void (*fun_ptr)(int) = &fun;
/* The above line is equivalent of following two
void (*fun_ptr)(int);
fun_ptr = &fun;
*/
// Invoking fun() using fun_ptr
(*fun_ptr)(10);
return 0;
}
1) Unlike normal pointers, a function pointer points to code, not data. Typically a function pointer stores the start of executable code.
2) Unlike normal pointers, we do not allocate de-allocate memory using function pointers.
3) A function’s name can also be used to get functions’ address. For example, in the below program, we have removed address operator ‘&’ in assignment. We have also changed function call by removing *, the program still works.
#include <stdio.h> // A normal function with an int parameter // and void return type void fun(int a) { printf("Value of a is %d\n", a); } int main() { void (*fun_ptr)(int) = fun; // & removed fun_ptr(10); // * removed return 0; |
5) Function pointer can be used in place of switch case. For example, in below program, user is asked for a choice between 0 and 2 to do different tasks.
#include <stdio.h>
void add(int a, int b)
{
printf("Addition is %d\n", a+b);
}
void subtract(int a, int b)
{
printf("Subtraction is %d\n", a-b);
}
void multiply(int a, int b)
{
printf("Multiplication is %d\n", a*b);
}
int main()
{
// fun_ptr_arr is an array of function pointers
void (*fun_ptr_arr[])(int, int) = {add, subtract, multiply};
unsigned int ch, a = 15, b = 10;
printf("Enter Choice: 0 for add, 1 for subtract and 2 "
"for multiply\n");
scanf("%d", &ch);
if (ch > 2) return 0;
(*fun_ptr_arr[ch])(a, b);
return 0;
}
typedef can be used to simplify the usage of function pointers.
#include<stdio.h>
void print_to_n(int n)
{
for (int i = 1; i <= n; ++i)
printf("%d\n", i);
}
void print_n(int n)
{
printf("%d\n, n);
}
typedef void (*printer_t)(int);printer_t p = &print_to_n;p(5);
The above code is equivlant to:
void (*p)(int) = &print_to_n;(*p)(5);
原文：https://www.cnblogs.com/anyu686/p/12694771.html