int类型*(*)(int *，int *(*)()) [英] type of int * (*) (int * , int * (*)())

问题描述

int *(*)(int *，int *(*)())

int * (*) (int * , int * (*)())

我想知道它是什么类型? ，有人可以举例说明使用这种类型的声明吗.

I'd like to know what type is it ? , can someone give an example of a declaration using this type.

任何帮助都会很棒.

谢谢.

推荐答案

它是指向返回int*并接受int*的函数的指针和指向返回int*的函数的指针(并接受未定义数量的参数；查看评论).

It is a pointer to function that returns int* and accepts int* and pointer to function that returns int* (and accepts undefined number of parameters; see comments).

一些例子(看起来不是很好，它只是构造为包含所提到的声明):

Some example (does not look very nice, it is just constructed to contain the mentioned declaration):

#include <stdio.h>

static int a = 10;
int* f1() {
    return &a;
}

static int b;
int* f2(int *j, int*(*f)()) {
    b = *j + *f();
    // this is just for demonstrational purpose, such usage
    // of global variable makes this function not thread-safe
    return &b;
} 


int main(int argc, char *argv[]) {
    int * (*ptr1)();
    int * (*ptr2) (int * , int * (*)());
    ptr1 = f1;
    ptr2 = f2;

    int i = 42;
    int *pi = ptr2(&i, ptr1);
    printf("%d\n", *pi);

    return 0;
}

// prints 52

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