c/c++实现TCP服务器和客户端

• TCP客户端代码
• TCP服务器代码

TCP客户端代码

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
​
#define MAXLINE 80
#define SERV_PORT 6666
​
int main(int argc, char *argv[])
{
    struct sockaddr_in servaddr;
    char buf[MAXLINE];
    int sockfd, n;
	char *str;
​
    if (argc != 2) {
        fputs("usage: ./client message\n", stderr);
        exit(1);
    }
	str = argv[1];
​
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
​
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    inet_pton(AF_INET, "127.0.0.1", &servaddr.sin_addr);
    servaddr.sin_port = htons(SERV_PORT);
​
    connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
​
    write(sockfd, str, strlen(str));
​
    n = read(sockfd, buf, MAXLINE);
    printf("Response from server:\n");
    write(STDOUT_FILENO, buf, n);
    close(sockfd);
​
    return 0;
}

由于客户端不需要固定的端口号，因此不必调用bind()，客户端的端口号由内核自动分配。注意，客户端不是不允许调用bind()，只是没有必要调用bind()固定一个端口号，服务器也不是必须调用bind()，但如果服务器不调用bind()，内核会自动给服务器分配监听端口，每次启动服务器时端口号都不一样，客户端要连接服务器就会遇到麻烦。

客户端和服务器启动后可以使用netstat命令查看链接情况：

TCP服务器代码

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
​
#define MAXLINE 80
#define SERV_PORT 6666
​
int main(void)
{
    struct sockaddr_in servaddr, cliaddr;
    socklen_t cliaddr_len;
    int listenfd, connfd;
    char buf[MAXLINE];
    char str[INET_ADDRSTRLEN];
    int i, n;
​
    listenfd = socket(AF_INET, SOCK_STREAM, 0);
​
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(SERV_PORT);
​
    bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
    listen(listenfd, 20);
​
    printf("Accepting connections ...\n");
    while (1) {
        cliaddr_len = sizeof(cliaddr);
        connfd = accept(listenfd, (struct sockaddr *)&cliaddr, &cliaddr_len);
        n = read(connfd, buf, MAXLINE);
        printf("received from %s at PORT %d\n",
        inet_ntop(AF_INET, &cliaddr.sin_addr, str, sizeof(str)),
        ntohs(cliaddr.sin_port));
        for (i = 0; i < n; i++)
            buf[i] = toupper(buf[i]);
        write(connfd, buf, n);
        close(connfd);
    }
    return 0;
}

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标签：cliaddr,c++,sin,TCP,include,buf,servaddr,客户端
来源： https://blog.csdn.net/weixin_44757097/article/details/116048979