在Linux上，C++可以通过多种方式实现进程间通信（IPC）。以下是一些常用的IPC方法：
管道是一种半双工的通信方式，通常用于父子进程之间的通信。
#include <iostream> #include <unistd.h> int main() { int pipefd[2]; pid_t pid; char buffer[10]; // 创建管道 if (pipe(pipefd) == -1) { perror("pipe"); exit(EXIT_FAILURE); } // 创建子进程 pid = fork(); if (pid == -1) { perror("fork"); exit(EXIT_FAILURE); } if (pid == 0) { // 子进程 close(pipefd[1]); // 关闭写端 read(pipefd[0], buffer, sizeof(buffer)); std::cout << "Child received: " << buffer << std::endl; close(pipefd[0]); } else { // 父进程 close(pipefd[0]); // 关闭读端 write(pipefd[1], "Hello from parent", 18); close(pipefd[1]); } return 0; } 命名管道允许不相关的进程之间进行通信。
#include <iostream> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> int main() { const char* fifo_name = "/tmp/myfifo"; mkfifo(fifo_name, 0666); int fd = open(fifo_name, O_RDWR); if (fd == -1) { perror("open"); exit(EXIT_FAILURE); } const char* message = "Hello from FIFO"; write(fd, message, strlen(message) + 1); char buffer[10]; read(fd, buffer, sizeof(buffer)); std::cout << "Received: " << buffer << std::endl; close(fd); unlink(fifo_name); return 0; } 消息队列允许进程以消息的形式进行通信。
#include <iostream> #include <sys/ipc.h> #include <sys/msg.h> #include <cstring> struct msg_buffer { long msg_type; char msg_text[100]; }; int main() { key_t key = ftok("msgqueue.c", 65); int msgid = msgget(key, 0666 | IPC_CREAT); if (msgid == -1) { perror("msgget"); exit(EXIT_FAILURE); } msg_buffer buffer; buffer.msg_type = 1; strcpy(buffer.msg_text, "Hello from message queue"); if (msgsnd(msgid, &buffer, sizeof(buffer.msg_text), 0) == -1) { perror("msgsnd"); exit(EXIT_FAILURE); } if (msgrcv(msgid, &buffer, sizeof(buffer.msg_text), 1, 0) == -1) { perror("msgrcv"); exit(EXIT_FAILURE); } std::cout << "Received: " << buffer.msg_text << std::endl; msgctl(msgid, IPC_RMID, NULL); return 0; } 共享内存允许多个进程共享同一块内存区域。
#include <iostream> #include <sys/ipc.h> #include <sys/shm.h> #include <cstring> int main() { key_t key = ftok("shmfile.c", 65); int shmid = shmget(key, 1024, 0666 | IPC_CREAT); if (shmid == -1) { perror("shmget"); exit(EXIT_FAILURE); } char* str = (char*) shmat(shmid, (void*)0, 0); if (str == (char*)(-1)) { perror("shmat"); exit(EXIT_FAILURE); } strcpy(str, "Hello from shared memory"); std::cout << "Message written in memory: " << str << std::endl; shmdt(str); return 0; } 信号量用于进程同步和互斥。
#include <iostream> #include <sys/ipc.h> #include <sys/sem.h> #include <sys/types.h> #include <unistd.h> union semun { int val; struct semid_ds *buf; unsigned short *array; }; int main() { key_t key = ftok("semaphore.c", 65); int semid = semget(key, 1, 0666 | IPC_CREAT); if (semid == -1) { perror("semget"); exit(EXIT_FAILURE); } union semun arg; arg.val = 1; // 初始化信号量为1 if (semctl(semid, 0, SETVAL, arg) == -1) { perror("semctl"); exit(EXIT_FAILURE); } // P操作（等待信号量） struct sembuf sb = {0, -1, SEM_UNDO}; if (semop(semid, &sb, 1) == -1) { perror("semop"); exit(EXIT_FAILURE); } std::cout << "Semaphore value: " << arg.val << std::endl; // V操作（释放信号量） sb.sem_op = 1; if (semop(semid, &sb, 1) == -1) { perror("semop"); exit(EXIT_FAILURE); } semctl(semid, 0, IPC_RMID, arg); return 0; } 套接字是一种通用的IPC机制，支持本地和网络通信。
#include <iostream> #include <sys/socket.h> #include <sys/un.h> #include <unistd.h> #include <string.h> int main() { struct sockaddr_un addr; int sockfd, newsockfd; socklen_t addr_len = sizeof(addr); char buffer[1024]; // 创建套接字 sockfd = socket(AF_UNIX, SOCK_STREAM, 0); if (sockfd == -1) { perror("socket"); exit(EXIT_FAILURE); } // 设置地址 memset(&addr, 0, sizeof(addr)); addr.sun_family = AF_UNIX; strncpy(addr.sun_path, "/tmp/unix_socket", sizeof(addr.sun_path) - 1); // 绑定套接字 if (bind(sockfd, (struct sockaddr*)&addr, addr_len) == -1) { perror("bind"); exit(EXIT_FAILURE); } // 监听连接 listen(sockfd, 5); newsockfd = accept(sockfd, (struct sockaddr*)&addr, &addr_len); if (newsockfd == -1) { perror("accept"); exit(EXIT_FAILURE); } // 接收数据 read(newsockfd, buffer, sizeof(buffer)); std::cout << "Received: " << buffer << std::endl; // 发送数据 const char* message = "Hello from UNIX socket"; write(newsockfd, message, strlen(message) + 1); close(newsockfd); close(sockfd); return 0; } 这些是Linux上C++常用的进程间通信方法。选择哪种方法取决于具体的应用场景和需求。
