TCP网络编程的基本流程

对于服务端,通常为以下流程:

调用socket函数创建socket
调用bind函数将socket绑定到某个IP和端口上
调用listen开始监听
当有客户端请求连接上来时,调用accept函数接受连接,产生一个新的socket
基于新产生的socket调用send或recv函数,开始与客户端进行数据交流
通信结束后,调用close函数关闭套接字

对于客户端,通常为以下流程:

调用socket函数创建客户端socket
调用connect函数尝试连接服务器
连接成功后调用send或recv函数,开始与服务器进行通信
通信结束后,调用close函数关闭socket

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服务端代码实现如下:

#include <iostream>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <cstring>
#pragma clang diagnostic push
#pragma ide diagnostic ignored "EndlessLoop"
using std::cout;
using std::endl;
int main(int argc,char * argv[])
{//1.create socketint listenfd = socket(AF_INET,SOCK_STREAM,0);if(listenfd == -1){cout<<"create listenfd failed"<<endl;return -1;}//2.Initialize server addressstruct sockaddr_in bindaddr{};bindaddr.sin_family =AF_INET;bindaddr.sin_addr.s_addr = htonl(INADDR_ANY);bindaddr.sin_port= htons(3000);if (bind(listenfd,(struct  sockaddr*) &bindaddr, sizeof(bindaddr)) == -1){cout<<"bind listen socket failed!"<<endl;return -1;}//3.Start listeningif(listen(listenfd,SOMAXCONN) == -1){cout<<"listen error"<<endl;return -1;}while (true){sockaddr_in clientaddr{};socklen_t  clientaddrlen = sizeof(clientaddr);//4.accept client connectint clientfd = accept(listenfd,(struct sockaddr*)&clientaddr,&clientaddrlen);if (clientfd != -1){//5.Receive data from the clientchar recvBuf[32]={0};int ret = recv(clientfd,recvBuf,32,0);if (ret > 0){cout<<"Receive data from the client:"<<recvBuf<<endl;ret = send(clientfd,recvBuf, strlen(recvBuf),0);if(ret != strlen(recvBuf))cout<<"send failed"<<endl;elsecout<<"send successfully"<<endl;}else{cout<<"Receive data error"<<endl;}close(clientfd);}}//7.close listenclose(listenfd);return 0;
}
#pragma clang diagnostic pop

客户端代码

#include <iostream>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <cstring>#define SERVER_ADDRESS "127.0.0.1"
#define SERVER_PORT 3000
#define SEND_DATA "helloworld"int main(int argc,char *argv[])
{//1.create socketint clientfd = socket(AF_INET,SOCK_STREAM,0);if(clientfd == -1){std::cout<<"create socket failed"<<std::endl;return -1;}//2.connect serversockaddr_in serveraddr;serveraddr.sin_family = AF_INET;serveraddr.sin_addr.s_addr= inet_addr(SERVER_ADDRESS);serveraddr.sin_port= htons(SERVER_PORT);if (connect(clientfd,(struct sockaddr*) &serveraddr, sizeof(serveraddr)) == -1){std::cout<<"connect socket error"<<std::endl;return -1;}//3. send data to serverint ret= send(clientfd,SEND_DATA, strlen(SEND_DATA),0);if (ret != strlen(SEND_DATA)){std::cout<<"send data failed"<<std::endl;return -1;}std::cout<<"successfully"<<SEND_DATA<<std::endl;//4.recv data from serverchar recvBuf[32] ={0};ret = recv(clientfd,recvBuf,32,0);if(ret >0){std::cout<<"sucessfully"<<std::endl;} else{std::cout<<"failed"<<recvBuf<<std::endl;}//5.close socketclose(clientfd);return 0;
}