Head Frist C学习之创建函数指针数组

#include <stdio.h>

enum response_type {DUMP,SECOND_CHANCE,MARRIAGE};
typedef struct{
    char *name;
    enum response_type type;
} response;

void dump(response r)
{
    printf("Dear %s,\n",r.name);
    puts("Unfortunately your last date contacted us to");
    puts("say that they will not be seeing you again");
}

void second_chance(response r)
{
    printf("Dear %s,\n",r.name);
    puts("Good news:you last date has asked us to");
    puts("arrange another meeting. please call ASAP.");
}

void marriage(response r)
{
    printf("Dear %s,\n",r.name);
    puts("Congratulations! Your last date has contacted");
    puts("us with a propisal of marriage.");
}

int main()
{
    response r[] = {
        {"Mike",DUMP},{"Luis",SECOND_CHANCE},
        {"Matt",SECOND_CHANCE},{"William",MARRIAGE}
    };
    int i;
    for(i = 0; i < 4; i++){
        switch(r[i].type){
            case DUMP:
                dump(r[i]);
                break;
            case SECOND_CHANCE:
                second_chance(r[i]);
                break;
            default:
                marriage(r[i]);
        }
    }
    return 0;
}

• 函数dump()、second()、amrriage()有着相同的返回值类型和心鬼头鬼脑的参数类型和列表。
• 如果想要在数组中保存函数，就要告诉编译器函数的具体特征。因此要是使用复杂的语法。

函数指针数组.jpg

• 在C语言中，创建枚举时会为每一个符号分配一个从0开始的数字，一次DUMP == 0, SECOND_CHANCE == !, MARRIGE ==2。

replies[SECOND_CHANCE] == second_chance

因此代码可以改成：

void (*replies[])(response) = {dump,second_chance,marriage};
int main()
{
    response r[] = {
        {"Mike",DUMP},  {"Luis",SECOND_CHANCE},
    {"Matt",SECOND_CHANCE},{"William",MARRIAGE}};
    int i;
    for(i = 0; i < 4; i++){
        (replies[r[i].type])(r[i]);
    }
    return 0;
}

函数指针数组2.jpg