c - 我找不到为什么我的程序总是说太低

Question

所以我一直在开发一个小程序，它制作一个文件，然后制作一个在该文件中生成随机数的子进程，然后让我的父进程读取该数字，然后玩一个简单的更高或更低的游戏.每当我运行它时，无论我输入多少数字，它总是说太低了。哪里出错了？

int main()
{
int fd, m;

    if (mkfifo("myfifo", 0666) < 0)
            perror("mkfifo"), exit(EXIT_FAILURE);

    if (fork() == 0)
    {
            fd = open("myfifo", O_WRONLY);
            srand(time(NULL));
            int n = rand() % 100 + 1;
            close(fd);
            exit(EXIT_SUCCESS);
    }

    fd = open("myfifo", O_RDONLY);
    read(fd, &m, sizeof(int));
    int c = -1;
    while ( m != c )
    {
            if ( c == -1)
                    printf("Guess a number 1-100\n");
            else if (c > m)
                    printf("Too high!\n");
            else if (c < m)
                    printf("Too low!\n");

            printf("Enter your guess: ");
            scanf ("%d",&c);
    }
    printf("Winner! Yes, the answer was %d \n",m);
    close(fd);
    wait(NULL);
    unlink("myfifo");
    exit(EXIT_SUCCESS);
}

Answer 1

您的子进程永远不会写入 fifo。它只是打开它，生成一个随机数，然后关闭它。试试写:

// inside fork() == 0 block
write(fd, &n, sizeof(n));