C语言send和recv接口使用实例

下面是一个简单的使用C语言的send和recv接口的例子，用于在客户端和服务器之间发送和接收数据：

服务端代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>

#define PORT 8080
#define MAX_SIZE 1024

int main() {
    int server_fd, new_socket, valread;
    struct sockaddr_in address;
    int opt = 1;
    int addrlen = sizeof(address);
    char buffer[MAX_SIZE] = {0};
    char *hello = "Hello from server";

    // 创建socket描述符
    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {
        perror("socket failed");
        exit(EXIT_FAILURE);
    }

    // 设置socket选项
    if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR | SO_REUSEPORT, &opt, sizeof(opt))) {
        perror("setsockopt failed");
        exit(EXIT_FAILURE);
    }

    // 绑定socket到本地地址
    address.sin_family = AF_INET;
    address.sin_addr.s_addr = INADDR_ANY;
    address.sin_port = htons(PORT);
    if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }

    // 监听socket
    if (listen(server_fd, 3) < 0) {
        perror("listen failed");
        exit(EXIT_FAILURE);
    }

    // 接受客户端连接
    if ((new_socket = accept(server_fd, (struct sockaddr *)&address, (socklen_t*)&addrlen)) < 0) {
        perror("accept failed");
        exit(EXIT_FAILURE);
    }

    // 接收客户端数据
    valread = recv(new_socket, buffer, MAX_SIZE, 0);
    printf("%s\n", buffer);

    // 发送响应数据给客户端
    send(new_socket, hello, strlen(hello), 0);
    printf("Hello message sent\n");

    return 0;
}

客户端代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>

#define PORT 8080
#define MAX_SIZE 1024

int main() {
    int sock = 0, valread;
    struct sockaddr_in serv_addr;
    char *hello = "Hello from client";
    char buffer[MAX_SIZE] = {0};

    // 创建socket描述符
    if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        printf("\n Socket creation error \n");
        return -1;
    }

    // 设置服务器地址
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(PORT);
    if(inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr)<=0) {
        printf("\nInvalid address/ Address not supported \n");
        return -1;
    }

    // 连接到服务器
    if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {
        printf("\nConnection Failed \n");
        return -1;
    }

    // 发送数据给服务器
    send(sock, hello, strlen(hello), 0);
    printf("Hello message sent\n");

    // 接收从服务器发送的响应数据
    valread = recv(sock, buffer, MAX_SIZE, 0);
    printf("%s\n",buffer);

    return 0;
}

在上述代码中，服务端和客户端分别创建了一个socket描述符，并分别使用bind、listen、accept、connect、send和recv函数来发送和接收数据。服务端先监听客户端连接，等待客户端发起连接请求，接收到连接请求后，服务端接收客户端数据，并发送响应数据给客户端。客户端则连接到服务端，并发送数据给服务端，然后接收从服务端发送的响应数据。