初探socket

//服务端代码
#include <iostream>
#include <unistd.h>
#include <cstring>
#include <arpa/inet.h>
#include <sys/socket.h>

using namespace std;

int main(int argc, char **argv) {
    if(argc != 2) {
        std::cerr << "Usage : " << argv[0] << std::endl;
        exit(1);
    }
    int server_sock;
    int client_sock;
    struct sockaddr_in server_addr;
    struct sockaddr_in client_addr;
    socklen_t client_addr_len;
    char message[] = "hello world";
    server_sock = socket(AF_INET, SOCK_STREAM, 0);//创建服务端socket
    if(server_sock == -1) {
        std::cerr << "socket error" << std::endl;
        exit(1);
    }
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);//#define	INADDR_ANY		((in_addr_t) 0x00000000)
    server_addr.sin_port = htons(atoi(argv[1]));
	//服务端需要bind绑定端口
    if(bind(server_sock, (struct sockaddr *) &server_addr, sizeof(server_addr)) == -1) {
        std::cerr << "bind failed" << std::endl;
        exit(1);
    }
	//设置监听上限
    if(listen(server_sock, 5) == -1) {
        std::cerr << "listen failed" << std::endl;
        exit(1);
    }
    client_addr_len = sizeof(client_addr);
	//接收连接
    client_sock = accept(server_sock,(struct sockaddr *)&client_addr, &client_addr_len);
    if(client_sock == -1) {
        std::cerr << "accept failed" << std::endl;
        exit(1);
    }
    write(client_sock, message, sizeof(message));
    close(client_sock);
    close(server_sock);
    return 0;
}

//客户端代码
#include <iostream>
#include <unistd.h>
#include <cstring>
#include <arpa/inet.h>
#include <sys/socket.h>

int main(int argc, char* argv[]) {
    int sock;
    struct sockaddr_in server;
    char message[30];
    int str_len;
    if(argc != 3) {
        std::cerr << "error:" << std::endl;
        exit(1);
    }
    sock = socket(AF_INET, SOCK_STREAM, 0);
    if(sock == -1) {
        std::cerr << "socket error: " << std::endl;
        exit(1);
    }
    memset(&server, 0, sizeof(server));
    server.sin_family = AF_INET;
    server.sin_addr.s_addr = inet_addr(argv[1]);
    server.sin_port = htons(atoi(argv[2]));
    if(connect(sock, (struct sockaddr *)&server, sizeof(server)) == -1) {
        std::cerr << "connect failed" << std::endl;
    }
    str_len = read(sock, message, sizeof(message) - 1);
    if(str_len == -1) {
        std::cerr << "read failed" << std::endl;
    }
    std::cout << message << std::endl;
    close(sock);
    return 0;
}