Question

我是线程主题的新手，我想创建一些进程和线程。但是我无法将我的价值传递给线程。

请告诉我代码中的错误。

编译时出现以下错误：

警告：传递'pthread_create'的参数2使得整数指针没有强制转换[-Wint-conversion]

这是我的代码：

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/fcntl.h>
#include <pthread.h>
///////////////////////////

void *print_fun(int *id)    {

    printf("Thread #%d is using the print function now! \n",a);
}

int main()
{
    int pid1,pid2,pid3;
    pthread_t t1,t2;

    pid1=fork();
    if (pid1==0)
    {//child #1
        pthread_create(&t1,1,print_fun,NULL);
        printf("The child of process #1 has been created!!\n");
    }
    if (pid1>0)
    {//Father #1
        printf("The process #1 has been created!!\n");
        pid2=fork();
        if (pid2>0)//Father #2
        {
            printf("The process #2 has been created!!\n");
            pid3=fork();
            if (pid3>0)//Father #3
            {
                printf("The process #3 has been created!!\n");
            }
            else
            {
                printf("There is error in the third fork!\n");
            }
        }
        else if(pid2==0)//child #2
        {
            pthread_create(&t1,2,print_fun,NULL);
            printf("The child of process #2 has been created!!\n");
        }
        else
        {
            printf("There is error in the second fork!\n");
        }
    }
    else
    {//error
        printf("There is error in the first fork!\n");
    }

    pthread_exit(NULL);
}

Answer 1

你可能想要这个：

pthread_create(&t1, NULL, print_fun, (void*)2);

而不是：

pthread_create(&t1, 2, print_fun, NULL);

pthread_create的第二个参数是指向pthread_attr_t结构或NULL的指针。

无法将值传递给C中的线程

1 个答案: