用回调做函数接口

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

typedef void (*Print) (void *);
typedef int (*Sum) (void * , void *);

struct func{
    Print print;
    Sum sum;
};


void print_char(void *data)
{
    char *ch = (char *)data;

    printf("func:%s ,%sn",__FUNCTION__, ch);
}

int sum_int(void *a, void *b)
{
    int sum = *(int *)a + *(int *)b;

    printf("func:%s, %dn",__FUNCTION__, sum);

    return sum;
}

int main(int argc, char *argv[])
{
    struct func f1;
    int sum = 0;
    int a = 5, b = 6;

    f1.print = print_char;
    f1.sum = sum_int;


    f1.print("hello,world");
    sum = f1.sum(&a, &b);

    printf("sum:%dn", sum);

    return 0;
}

运行结果：

func:print_char ,hello,world
func:sum_int, 11
sum:11

参考：
《系统程序员成长计划》