Linux Pthread参数 [英] Linux Pthread argument

问题描述

这是我的代码.非常简单.

This is my code. It's very simple.

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

void *func(void *arg)
{
    printf("ID=%d\n", *(int*)arg);
    pthread_exit(NULL);
}

int main()
{
    pthread_t pt[4];
    int i;

    for (i = 0; i < 4; i++)
    {
        int temp = i;
        pthread_create(&pt[i], NULL, func, (void*)&temp);
    }
    sleep(1);
    return 0;
}

我编译了它:

gcc p_test.c -lpthread

我跑了.打印2 2 3 3.我又跑了一次.它打印了2 3 3 2.

I ran it. It printed 2 2 3 3. I ran it again. It printed 2 3 3 2.

我的问题是:

为什么2或3打印两次?

为什么不打印1 3 2 0或其他任何结果?

Why didn't it print 1 3 2 0 or any other results?

推荐答案

此处的主要问题是您要获取局部变量temp的地址，然后在变量范围之外使用该指针-如退出循环的一次迭代后，指向temp的指针将立即失效，并且您不得取消引用它.

The major problem here is that you're taking the address of the local variable temp, and then using that pointer outside the scope of the variable - as soon as you exit one iteration of the loop, your pointer to temp becomes invalid and you must not dereference it.

这篇关于Linux Pthread参数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！