创建了两个子进程父进程应该一直执行，直到一个子进程终止我如何用c编写这个程序？

如何解决创建了两个子进程父进程应该一直执行，直到一个子进程终止我如何用c编写这个程序？

两个子进程通过不同的方法进行排序。我希望父进程等到至少一个子进程终止。这段代码没有给我所需的输出。

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>


int main(int argc,char *argv[])
{
    pid_t pid1,pid2;
    int status;
    pid1 = fork();
    pid2 = fork();
    if(pid1==0 && pid2 !=0)
    {
        //first child performing selection sort
        exit(0);
    }
    if(pid1>0 && pid2 > 0)
    {
        wait(&status);
        if(WIFEXITED(status))
        {
            printf("Parent process executed %d\n",WEXITSTATUS(status));
        }
    }
    if(pid1>0 && pid2 ==0)
    {
        //second child performing bubble sort
        
        exit(0);
    }
    
}

解决方法

pid2 = fork() 由父项和从 pid1 = fork() 创建的第一个子项执行，这不是您希望从问题描述中得到的。

你可能想要这样的东西

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>

int main(int argc,char *argv[]) {

    pid_t pid1,pid2;
    int status;
    pid1 = fork();

    if(pid1 == 0) {
        //first child performing selection sort

        exit(0);
    }

    if(pid1 > 0) {
        pid2 = fork();

        if(pid2 == 0) {
            //second child performing bubble sort
        
            exit(0);
        }

        if(pid2 > 0) {
            wait(&status);

            if(WIFEXITED(status)) {
                printf("Parent process executed %d\n",WEXITSTATUS(status));
            }
        }
    }
}

,

当您执行 fork() 时，您有一个新的子进程与父进程在同一点开始运行。所以你应该确保只有父进程调用第二个 fork()。

键：fork() 将在子进程上返回 0。

方法如下：

代码

#include <stdio.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>

int main(void)
{
    int status;
    pid_t ret,pid1,pid2;

    pid1 = fork();
    if (pid1 == 0) {
        // First child performing selection sort
        printf("Do selection sort here...\n");
        sleep(5);

        printf("Selection sort finished\n");
        exit(0);
    }


    pid2 = fork();
    if (pid2 == 0) {
        // Second child performing bubble sort
        printf("Do bubble sort here...\n");
        sleep(2);

        printf("Bubble sort finished\n");
        // The parent must get exit code 100 from this
        exit(100);
    }


    // Parent process waits until at least one child process terminates
    do {

        status = 0;
        ret = wait(&status);
        if (WIFEXITED(status)) {
            printf("Child process %d has exited with exit code: %d\n",ret,WEXITSTATUS(status));
            break;
        }

        if (ret < 0) {
            printf("wait() error: %s\n",strerror(errno));
            break;
        }

        /* If we reach here,child may be traced or continued. */
    } while (1);

    printf("Parent has finished its waiting state...\n");
    return 0;
}

编译运行

ammarfaizi2@integral:/tmp$ gcc -Wall -Wextra test.c -o test
ammarfaizi2@integral:/tmp$ ./test
Do bubble sort here...
Do selection sort here...
Bubble sort finished
Child process 143748 has exited with exit code: 100
Parent has finished its waiting state...
ammarfaizi2@integral:/tmp$ Selection sort finished

在这种情况下，当一个子进程（至少一个）终止时，父进程会停下来等待。所以你会在父进程终止后看到“选择排序完成”，因为我们模拟选择排序为 5 秒工作，冒泡排序为 3 秒工作。