用c语言创建2个进程互斥地向管道写数据在父进程中读不同的数据。

以下是使用C语言创建两个进程，互斥地向管道写数据，并在父进程中读取不同数据的示例代码：

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

#define BUFFER_SIZE 25
#define READ_END 0
#define WRITE_END 1

int main(void)
{
    char write_msg1[BUFFER_SIZE] = "Hello from process 1!";
    char write_msg2[BUFFER_SIZE] = "Hello from process 2!";
    char read_msg1[BUFFER_SIZE];
    char read_msg2[BUFFER_SIZE];
    int fd[2];
    pid_t pid;

    // Create the pipe
    if (pipe(fd) == -1) {
        fprintf(stderr, "Pipe failed");
        return 1;
    }

    // Fork the first child process
    pid = fork();

    if (pid < 0) {
        fprintf(stderr, "Fork failed");
        return 1;
    } else if (pid == 0) {
        // Child process 1
        // Close the unused write end of the pipe
        close(fd[READ_END]);

        // Write to the pipe
        write(fd[WRITE_END], write_msg1, strlen(write_msg1) + 1);

        // Close the write end of the pipe
        close(fd[WRITE_END]);

        exit(0);
    } else {
        // Fork the second child process
        pid = fork();

        if (pid < 0) {
            fprintf(stderr, "Fork failed");
            return 1;
        } else if (pid == 0) {
            // Child process 2
            // Close the unused write end of the pipe
            close(fd[READ_END]);

            // Write to the pipe
            write(fd[WRITE_END], write_msg2, strlen(write_msg2) + 1);

            // Close the write end of the pipe
            close(fd[WRITE_END]);

            exit(0);
        } else {
            // Parent process
            // Close the write end of the pipe
            close(fd[WRITE_END]);

            // Read from the pipe
            read(fd[READ_END], read_msg1, BUFFER_SIZE);
            read(fd[READ_END], read_msg2, BUFFER_SIZE);

            // Close the read end of the pipe
            close(fd[READ_END]);

            printf("Message 1: %s\nMessage 2: %s\n", read_msg1, read_msg2);

            // Wait for both child processes to finish
            wait(NULL);
            wait(NULL);
        }
    }

    return 0;
}

在这个示例代码中，我们首先使用pipe()函数创建了一个管道，并创建了两个子进程。子进程1向管道写入一个消息，子进程2向管道写入另一个消息。在父进程中读取这两个消息并打印它们。注意到我们在父进程中调用了wait()函数，以等待两个子进程都结束。这样做是为了确保子进程完成它们的任务后，父进程才会继续执行。这样可以避免出现竞态条件（race condition）的情况