C指针-指向相同的地址 [英] C pointers - Point to the same address

问题描述

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

void foo(int *a, int *b);

void foo(int *a, int *b) {
    *a = 5;
    *b = 6;
    a = b;
}

int main(void) {
    int a, b;
    foo(&a, &b);
    printf("%d, %d", a, b);
    return 0;
}

为什么a = b(foo)不起作用? printf输出"5，6" 谢谢.

Why a = b (foo) doesn't work? printf outputs "5, 6" Thank you.

推荐答案

它确实有效；它只是没有按照您的想法做.

It does work; it just doesn't do what you think it does.

在foo()中，a = b将指针a更改为指向b所指向的内容.它对功能以外的任何内容均无影响；它只会更改指针.

In foo(), a = b changes the pointer a to point to whatever b points to. It has no effect on anything outside of the function; it only changes the pointers.

如果您想将a指向的int的值更改为与b指向的int的值相同，则需要使用*a = *b，类似于您执行函数中已经有分配.

If you want to change the value of the int pointed to by a to be the same as the value of the int pointed to by b, you need to use *a = *b, similar to how you do the assignments in the function already.

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