函式指標陣列

概念：
陣列元素是指標函式的陣列叫做指標函式陣列，通常我們也叫做轉移表
定義個初始化：
返回型別說明符 (*函式指標陣列名[])(引數列表) = {函式指標/函式名，…};
如下： int (*fun_array[])(int,int) = {add,del,mul,div};

函式指標陣列的使用如下：
函式指標陣列名下標或者(*函式指標陣列名)下標；
下面是給出的示例程式碼：

#include<stdio.h>

int add(int a,int b); 
int sub(int a,int b);
 
 
int mul(int a,int b); 
int div(int a,int b); 
void make_menu();


int main(int argc,char* argv[]){
    int (*fun_array [])(int,int) = {add,sub,mul,div};
    int cmd = 0;
    int result =  0;  
    int num1,num2;
    while(1){
        make_menu();
        printf("please select a num what you want :");
        scanf("%d
 
",&cmd);
        if(cmd == 0){ 
            break;
        }else{
            printf("please input two num you want!\n");
            scanf("%d %d",&num1,&num2);
            result = fun_array[cmd-1](num1,num2);
            printf("the form_1_result you want to calculate is:%d\n",result);
            int
 
 (*fun_pointer)(int,int) = fun_array[cmd-1];
            result = fun_pointer(num1,num2);
            printf("the form_2_result you want to calculate is:%d\n",result);
            result = (*fun_array[cmd-1])(num1,num2);
            printf("the form_3_result you want to calculate is:%d\n",result);

        }
    }   
    return 0;
}

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

int sub(int a,int b){ 
    return a - b;
}
int mul(int a,int b){ 
    return a * b;
}

int div(int a,int b){
    return a/b;
}




void make_menu(){
    printf("=====================\n");
    printf("1:add\n");
    printf("2:sub\n");
    printf("3:mul\n");
    printf("4:div\n");
    printf("0:quit\n");
    printf("=====================\n");
}

由上面我們可以看出來函式指標陣列的三種呼叫方式：
int (*pointer)(int ,int ) = fun_array[i];
int result = pointer(num1,num2);
或者：
int result = fun_arrayi;
或者：
int result =*(fun_array[i])(num1,num2);
第三種形式我們是不經常會用到的，

結果：

1:add
2:sub
3:mul
4:div

0:quit

please select a num what you want :1
please input two num you want!
10 11
the form_1_result you want to calculate is:21
the form_2_result you want to calculate is:21
the form_3_result you want to calculate is:21

函式指標陣列的運用的注意點：

1. 函式的返回型別一樣，並且函式的形參也是要一樣
2. 通常是在swith函式中去做這樣的函式指標陣列，便於簡化程式碼