udp和tcp的区别

区别

  • udp-无连接，数据报，不安全不可靠不稳定
  • tcp-面向连接，数据流，安全可靠稳定

udp

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// Server.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
//
#define _WINSOCK_DEPRECATED_NO_WARNINGS
#include <iostream>
using namespace std;
#define WIN32_LEAN_AND_MEAN//仅保留windows.h中的必要的头文件
//如果不加这一行则要把Winsock2.h放到windows.h前面，否则会因重定义而报错
#include <windows.h>
#include <Winsock2.h>
#pragma comment(lib,"Ws2_32.lib")

int main()
{
    WORD wVersionRequested;
    WSADATA wsaData;
    int err;
    wVersionRequested = MAKEWORD(2, 2);
    err = WSAStartup(wVersionRequested, &wsaData);
    if (err != 0) 
    {                                 
        return 0;
    }
                                        
    if (LOBYTE(wsaData.wVersion) != 2 ||
        HIBYTE(wsaData.wVersion) != 2) 
    {                                 
        WSACleanup();
        return 0;
    }

    SOCKET sockServer = socket(AF_INET, SOCK_DGRAM , IPPROTO_UDP);
    if (sockServer == INVALID_SOCKET)
    {
        cout << "socket 失败" << endl;
        return 0;
    }
    //127.0.0.1-回环地址
    sockaddr_in si;
    si.sin_family = AF_INET;
    si.sin_port = htons(0x7788);
    si.sin_addr.S_un.S_addr = inet_addr("127.0.0.1");//0x0100007f;
    int nRet = bind(sockServer, (sockaddr*)&si, sizeof(si));
    if (nRet == SOCKET_ERROR)
    {
        cout << "bind 失败" << endl;
        return 0;
    }

    for (int i = 0; i < 0x100000; ++i)
    {
        int nVal = 0;
        sockaddr_in siFrom = {};
        int nSizeofSi = sizeof(sockaddr_in);
        recvfrom(sockServer, (char*)&nVal, sizeof(nVal), 0, (sockaddr*)&siFrom, &nSizeofSi);
        printf("val:%08X \r\n", nVal);
    }

    system("pause");
    cout << "Hello World!\n";
    return 0;
}
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// Client.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
//
#define _WINSOCK_DEPRECATED_NO_WARNINGS
#include <iostream>
using namespace std;
#define WIN32_LEAN_AND_MEAN//仅保留windows.h中的必要的头文件
//如果不加这一行则要把Winsock2.h放到windows.h前面，否则会因重定义而报错
#include <windows.h>
#include <Winsock2.h>
#pragma comment(lib,"Ws2_32.lib")

int main()
{
    WORD wVersionRequested;
    WSADATA wsaData;
    int err;
    wVersionRequested = MAKEWORD(2, 2);
    err = WSAStartup(wVersionRequested, &wsaData);
    if (err != 0)
    {
        return 0;
    }

    if (LOBYTE(wsaData.wVersion) != 2 ||
        HIBYTE(wsaData.wVersion) != 2)
    {
        WSACleanup();
        return 0;
    }

    SOCKET sockClient = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
    if (sockClient == INVALID_SOCKET)
    {
        cout << "socket 失败" << endl;
        return 0;
    }
    sockaddr_in si;
    si.sin_family = AF_INET;
    si.sin_port = htons(0x7788);//h-host to n-network s-short ntohs
    si.sin_addr.S_un.S_addr = inet_addr("127.0.0.1");//0x0100007f;

    for (int i = 0; i < 0x100000; ++i)
    {
        sendto(sockClient, (char*)&i, sizeof(i), 0, (sockaddr*)&si, sizeof(si));
    }

    system("pause");
    cout << "Hello World!\n";
}

image-20240719221629116

udp可能丢包，还可能出现先发出的包比后发的包晚收到

tcp

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// Server.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
//
#define _WINSOCK_DEPRECATED_NO_WARNINGS
#include <iostream>
using namespace std;
#define WIN32_LEAN_AND_MEAN//仅保留windows.h中的必要的头文件
//如果不加这一行则要把Winsock2.h放到windows.h前面，否则会因重定义而报错
#include <windows.h>
#include <Winsock2.h>
#pragma comment(lib,"Ws2_32.lib")
DWORD WINAPI WorkThreadFunc(LPVOID lpParam);
int main()
{
    WORD wVersionRequested;
    WSADATA wsaData;
    int err;
    wVersionRequested = MAKEWORD(2, 2);
    err = WSAStartup(wVersionRequested, &wsaData);
    if (err != 0) 
    {                                 
        return 0;
    }
                                        
    if (LOBYTE(wsaData.wVersion) != 2 ||
        HIBYTE(wsaData.wVersion) != 2) 
    {                                 
        WSACleanup();
        return 0;
    }

    SOCKET sockServer = socket(AF_INET, SOCK_STREAM , IPPROTO_TCP);
    if (sockServer == INVALID_SOCKET)
    {
        cout << "socket 失败" << endl;
        return 0;
    }
    //127.0.0.1-回环地址
    sockaddr_in si;
    si.sin_family = AF_INET;
    si.sin_port = htons(0x7788);
    si.sin_addr.S_un.S_addr = inet_addr("127.0.0.1");//0x0100007f;
    int nRet = bind(sockServer, (sockaddr*)&si, sizeof(si));
    if (nRet == SOCKET_ERROR)
    {
        cout << "bind 失败" << endl;
        return 0;
    }

    nRet = listen(sockServer, 1);
    if (nRet == SOCKET_ERROR)
    {
        cout << "listen 失败" << endl;
        return 0;
    }

    sockaddr_in siClient;
    int nLen = sizeof(siClient);
    SOCKET sock = accept(sockServer, (sockaddr*)&siClient, &nLen);
    if (sock == INVALID_SOCKET)
    {
        cout << "accept 失败" << endl;
    } 

    for (int i = 0; i < 0x100000; ++i)
    {
        int nVal = 0;
        sockaddr_in siFrom = {};
        int nSizeofSi = sizeof(sockaddr_in);
        recv(sock, (char*)&nVal, sizeof(nVal), 0);
        printf("i:%d val:%08X \r\n", i, nVal);
    }

    system("pause");
    cout << "Hello World!\n";
    return 0;
}
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// Client.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
//
#define _WINSOCK_DEPRECATED_NO_WARNINGS
#include <iostream>
using namespace std;
#define WIN32_LEAN_AND_MEAN//仅保留windows.h中的必要的头文件
//如果不加这一行则要把Winsock2.h放到windows.h前面，否则会因重定义而报错
#include <windows.h>
#include <Winsock2.h>
#pragma comment(lib,"Ws2_32.lib")

int main()
{
    WORD wVersionRequested;
    WSADATA wsaData;
    int err;
    wVersionRequested = MAKEWORD(2, 2);
    err = WSAStartup(wVersionRequested, &wsaData);
    if (err != 0)
    {
        return 0;
    }

    if (LOBYTE(wsaData.wVersion) != 2 ||
        HIBYTE(wsaData.wVersion) != 2)
    {
        WSACleanup();
        return 0;
    }

    SOCKET sockClient = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (sockClient == INVALID_SOCKET)
    {
        cout << "socket 失败" << endl;
        return 0;
    }
    sockaddr_in si;
    si.sin_family = AF_INET;
    si.sin_port = htons(0x7788);
    si.sin_addr.S_un.S_addr = inet_addr("127.0.0.1");//0x0100007f;
    int nRet = connect(sockClient, (sockaddr*)&si, sizeof(si));
    if (nRet == SOCKET_ERROR)
    {
        cout << "connect 失败" << endl;
        return 0;
    }

    for (int i = 0; i < 0x100000; ++i)
    {
        send(sockClient, (char*)&i, sizeof(i), 0);
    }

    system("pause");
    cout << "Hello World!\n";
}

image-20240719223437679

tcp不会丢包，而且会按顺序接受到包