C语言socket通信实例

下面是一个简单的C语言socket通信实例，演示了如何使用socket在两个程序之间进行通信。

客户端代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>

int main()
{
    int sockfd, portno, n;
    struct sockaddr_in serv_addr;
    struct hostent *server;

    char buffer[256];
    portno = 8888;

    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0) 
    {
        perror("Error opening socket");
        exit(1);
    }

    server = gethostbyname("127.0.0.1");
    if (server == NULL) 
    {
        fprintf(stderr,"Error, no such host\n");
        exit(1);
    }

    bzero((char *) &serv_addr, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    bcopy((char *)server->h_addr, (char *)&serv_addr.sin_addr.s_addr, server->h_length);
    serv_addr.sin_port = htons(portno);

    if (connect(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0) 
    {
        perror("Error connecting");
        exit(1);
    }

    printf("Please enter the message: ");
    bzero(buffer,256);
    fgets(buffer,255,stdin);

    n = write(sockfd, buffer, strlen(buffer));
    if (n < 0) 
    {
        perror("Error writing to socket");
        exit(1);
    }

    bzero(buffer,256);
    n = read(sockfd, buffer, 255);
    if (n < 0) 
    {
        perror("Error reading from socket");
        exit(1);
    }

    printf("%s\n",buffer);
    close(sockfd);
    return 0;
}

服务器端代码：

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

int main()
{
    int sockfd, newsockfd, portno, clilen;
    char buffer[256];
    struct sockaddr_in serv_addr, cli_addr;
    int n;

    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0) 
    {
        perror("Error opening socket");
        exit(1);
    }

    bzero((char *) &serv_addr, sizeof(serv_addr));
    portno = 8888;

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    serv_addr.sin_port = htons(portno);

    if (bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0) 
    {
        perror("Error on binding");
        exit(1);
    }

    listen(sockfd,5);
    clilen = sizeof(cli_addr);

    newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &clilen);
    if (newsockfd < 0) 
    {
        perror("Error on accept");
        exit(1);
    }

    bzero(buffer,256);
    n = read(newsockfd, buffer, 255);
    if (n < 0) 
    {
        perror("Error reading from socket");
        exit(1);
    }

    printf("Here is the message: %s\n", buffer);

    n = write(newsockfd,"I got your message",18);
    if (n < 0) 
    {
        perror("Error writing to socket");
        exit(1);
    }

    close(newsockfd);
    close(sockfd);
    return 0;
}

在这个例子中，客户端连接到服务器，并发送一条消息。服务器接收该消息并发送一条回复。客户端接收回复后关闭socket连接。