函数指针与指针函数练习

#include<stdio.h>
int add(int a, int b)
{
        return a+b;

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

}
/*参数是函数指针的函数*/
int f1(int a, int b,int (*pf)(int, int))
{
        return pf(a,b);

}
int sum;
/*参数是函数指针，返回值是指针的函数*/
int *f2(int a, int b, int (*pf)(int, int))
{
        sum = pf(a,b);
        return  sum;
}
/*这是一个返回函数指针的函数
 函数指针所指向的函数参数是(int, int)，返回值是int */
//int (*pf)(int, int)  f3(int a, int b, int (*pf)(int, int))
//int (int, int) * f3(int a, int b, int (*pf)(int, int)) 
int (*f3(int a, int b, int(*pf)(int, int)))(int, int)
{
        sum = pf(a,b);
        return pf;
}

int main()
{
        int x = 10;
        int y = 20;
        int (*pfunc[2])(int, int);//定义函数指针数组
        int (*fp[2])(int, int);//定义函数指针
        int (*(*fp3[2])(int a, int b, int(*pf)(int, int)))(int, int);
        //定义函数指针数组，指向这个函数的原型返回是一个函数指针
        fp3[0] = f3;
        fp3[1] = f3;
        fp[0] = fp3[0](x,y,add);//返回函数指针，让fp[0]->int pf(int, int)
        fp[1] = fp3[1](x,y,sub);//
        pfunc[0] = add;
        pfunc[1] = sub;
        printf("pfunc[0]:x + y = %d\n",(*pfunc[0])(x,y));
        printf("pfunc[1]:x - y = %d\n",(*pfunc[1])(x,y));
        printf("fl:      x + y = %d\n",f1(x,y,pfunc[0]));
        printf("fl:      x - y = %d\n",f1(x,y,pfunc[1]));
        printf("f2:      x + y = %d\n",*f2(x,y,pfunc[0]));
        printf("f2:      x - y = %d\n",*f2(x,y,pfunc[1]));
        printf("f3:      x + y = %d\n",fp[0](x,y));
        printf("f3:      x + y = %d\n",fp[1](x,y));

}