"父子之间通过管道进行通信"

Question

I want a program where the parent and child talk each other.我想要一个父母和孩子互相交谈的程序。 so the output would be:所以输出将是：

p: value p：值
c: value c：价值
p: word p：单词
c: word c：单词

and so on.....等等.....

Below there is an example of code where the output makes first talk the parent and after the childs.下面是一个代码示例，其中输出首先与父级对话，然后在子级对话。 How can I correct the code?如何更正代码？

    for(int i=0; i<N; i++){
            pid=fork();
            if(pid==-1){
                    perror("fork\n");
                    exit(EXIT_FAILURE);
            }
            else if(pid==0){
                    srand(time(NULL));
                    int c;
                    read(fd[i][0], &c, 1);
                    printf("c: value: %d\n", c);
                    char word[c];
                    read(fd[i][0],&word, sizeof(word));
                    printf("c: word: %s\n", word);
                    int sum;
                    sum=c*i;
                    write(fd[i][1], &sum, sizeof(int));
                    printf("c: sended %d\n", sum);
                    int flag=0;
                    printf("flag :%d\n", flag);
                    read(fd[i][0], &flag, sizeof(int));
                    printf("c: flag= %d ->exit\n", flag);
                    exit(1);
            }else{
                    int c;
                    c=rand()%100+1;
                    write(fd[i][1], &c, sizeof(int));
                    printf("p: value: %d\n", c);
                    char word[c];
                    write(fd[i][1], &word, sizeof(word));
                    printf("p: word: %s\n", word);
                    int sum;
                    read(fd[i][0], &sum, sizeof(int));
                    printf("p: sum is: %d\n", sum);
                    int flag=1;
                    write(fd[i][1], &flag, sizeof(int));
                    printf("par: flag exit %d\n", flag);
                    wait(NULL);
            }
    }

Answer 1

To have duplex communication between two processes, you need two<\/em> pipes:要在两个进程之间进行双工通信，您需要两个<\/em>管道：

One for parent to child communication;一种用于亲子交流；<\/li>

And one for child to parent communication还有一个供孩子与父母交流<\/li><\/ol>
If you use the same pipe for both, then you can end up with a situation like the child writing something to the pipe, and directly read it back again (and the parent will never see the data).如果您对两者都使用相同的管道，那么您最终可能会遇到这样的情况，例如孩子向管道写入内容，然后直接再次读回（并且父级将永远看不到数据）。
This could for example happen with eg例如，这可能发生在例如

write(fd[i][1], &sum, sizeof(int)); \/\/ ... \/\/ Could read sum that was written just above in the same process read(fd[i][0], &flag, sizeof(int));<\/code><\/pre> in your child process.在您的子进程中。
 For the example of the write<\/code> and read<\/code> calls shown above, you could have something like:对于上面显示的write<\/code>和read<\/code>调用示例，您可能有如下内容：
 int parent_to_child[2]; \/\/ Pipe where parent process write and child reads int child_to_parent[2]; \/\/ Pipe where parent process reads and child writes pipe(parent_to_child); pipe(child_to_parent); \/\/ ... pid = fork(); if (pid == 0) { \/\/ Other code... \/\/ Child writes to parent write(child_to_parent[1], &sum, sizeof(int)); \/\/ Child reads from parent read(parent_to_child[0], &flag, sizeof(int)); \/\/ ... } else { \/\/ Other code... \/\/ Parent reads from child read(child_to_parent[0], &sum, sizeof(int)); \/\/ Parent writes to child write(parent_to_child[1], &flag, sizeof(int)); \/\/ ... }<\/code><\/pre>"

"父子之间通过管道进行通信"

问题描述

1 个解决方案

解决方案1
0 已采纳 2022-02-06 08:27:00

"父子之间通过管道进行通信"

问题描述

1 个解决方案

解决方案1 0 已采纳 2022-02-06 08:27:00

解决方案1
0 已采纳 2022-02-06 08:27:00