管道编程作业

#include <fcntl.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
 
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <iostream>
 
int main() {
    int fd[2];
    if (pipe(fd) == -1) {
        perror("pipe");
        return EXIT_FAILURE;
    }
 
    pid_t pid = fork();
    if (pid < 0) {
        perror("fork");
        return EXIT_FAILURE;
    }
 
    if (pid > 0) {
        close(fd[0]);
        std::cout << "请输入文本（Ctrl+D结束）：" << std::endl;
        char buf;
        while (std::cin.get(buf)) {
            if (write(fd[1], &buf, 1) == -1) {
                perror("write to pipe");
                break;
            }
        }
        close(fd[1]);
        wait(nullptr);
    } else {
        close(fd[1]);
 
        std::ofstream fileLetters("file1.txt");
        std::ofstream fileDigits("file2.txt");
        std::ofstream fileOthers("file3.txt");
 
        char ch;
        while (read(fd[0], &ch, 1) > 0) {
            if (std::isalpha(static_cast<unsigned char>(ch))) {
                fileLetters << ch;
            } else if (std::isdigit(static_cast<unsigned char>(ch))) {
                fileDigits << ch;
            } else {
                fileOthers << ch;
            }
        }
 
        close(fd[0]);
        fileLetters.close();
        fileDigits.close();
        fileOthers.close();
    }
 
    return 0;
}