1
#define _WINSOCK_DEPRECATED_NO_WARNINGS
2

3
#include <iostream>
4
#include <cstring>
5
#include <Winsock2.h>
6

7
#pragma comment(lib, "Ws2_32.lib")

1
WORD version = MAKEWORD(2, 2);
2
WSADATA data = {};
3

4
int err = WSAStartup(version, &data);
5
if (err != 0) {
6
    cout << "WSAStartup fail" << endl;
7
    return 1;
8
}

1
if (data.wVersion != version) {
2
    WSACleanup();
3
    cout << "WSAStartup version error" << endl;
4
    return 1;
5
}

1
SOCKET s = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);

1
if (s == INVALID_SOCKET) {
2
    cout << "socket error: " << WSAGetLastError() << endl;
3
    WSACleanup();
4
    return 1;
5
}

1
struct sockaddr_in {
2
    short          sin_family;  // 地址族
3
    unsigned short sin_port;    // 端口
4
    struct in_addr sin_addr;    // IPv4 地址
5
    char           sin_zero[8]; // 填充
6
};

1
sockaddr_in addr = {};
2
addr.sin_family = AF_INET;
3
addr.sin_port = htons(12345);
4
addr.sin_addr.S_un.S_addr = htonl(INADDR_ANY);

1
int err = bind(s, reinterpret_cast<sockaddr*>(&addr), sizeof(addr));

1
if (err == SOCKET_ERROR) {
2
    cout << "bind error: " << WSAGetLastError() << endl;
3
    closesocket(s);
4
    WSACleanup();
5
    return 1;
6
}

1
int recvfrom(
2
    SOCKET s,
3
    char* buf,
4
    int len,
5
    int flags,
6
    sockaddr* from,
7
    int* fromlen
8
);

1
char recvBuf[4096] = "";
2
sockaddr_in addrFrom = {};
3
int addrFromSize = sizeof(addrFrom);

1
int nRecvNum = recvfrom(
2
    s,
3
    recvBuf,
4
    sizeof(recvBuf),
5
    0,
6
    reinterpret_cast<sockaddr*>(&addrFrom),
7
    &addrFromSize
8
);

1
if (nRecvNum > 0) {
2
    int end = (nRecvNum < static_cast<int>(sizeof(recvBuf)))
3
        ? nRecvNum
4
        : static_cast<int>(sizeof(recvBuf)) - 1;
5
    recvBuf[end] = '\0';
6
}

1
cout << "ip: " << inet_ntoa(addrFrom.sin_addr)
2
          << " say: " << recvBuf << endl;

1
int sendto(
2
    SOCKET s,
3
    const char* buf,
4
    int len,
5
    int flags,
6
    const sockaddr* to,
7
    int tolen
8
);

1
char sendBuf[4096] = "";
2
cin >> sendBuf;
3

4
int nSendNum = sendto(
5
    s,
6
    sendBuf,
7
    static_cast<int>(strlen(sendBuf)) + 1,
8
    0,
9
    reinterpret_cast<sockaddr*>(&addrFrom),
10
    addrFromSize
11
);

1
if (nSendNum == SOCKET_ERROR) {
2
    cout << "sendto error: " << WSAGetLastError() << endl;
3
    break;
4
}

1
#define _WINSOCK_DEPRECATED_NO_WARNINGS
2
#include<iostream>
3
#include<Winsock2.h>
4

5
#pragma comment(lib,"Ws2_32.lib")
6
using namespace std;
7
int main() {
8
  //1、加载库
9
  WORD version = MAKEWORD(2, 2);
10
  WSADATA data = {};
11
  int err = WSAStartup(version, &data);
12
  if (0 != err) {
13
    cout << "WSAStartup fail" << endl;
14
    return 1;
15
  }
16

17
  if (data.wVersion == version) {
18
    cout << "WSAStartup success" << endl;
19
  }
20
  else {
21
    WSACleanup();
22
    cout << "WSAStartup version error" << endl;
23
    return 1;
24
  }
25
  //2、创建套接字
26
  SOCKET s = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
27
  if (INVALID_SOCKET == s) {
28
    cout << "socket error: " << WSAGetLastError() << endl;
29
    WSACleanup();
30
    return 1;
31
  }
32
  else {
33
    cout << "socket success" << endl;
34
  }
35
  //3、绑定端口和ip
36
  sockaddr_in addr = {};
37
  addr.sin_family = AF_INET;
38
  addr.sin_port = htons(12345);
39
  addr.sin_addr.S_un.S_addr = INADDR_ANY;
40
  err = bind(s,(sockaddr*)&addr,sizeof(addr));
41
  if (SOCKET_ERROR == err) {
42
    cout << "bind error:" << WSAGetLastError() << endl;
43
    closesocket(s);
44
    WSACleanup();
45
    return 1;
46
  }
47
  else {
48
    cout << "bind success" << endl;
49
  }
50
  int nRecvNum = 0;
51
  int nSendNum = 0;
52
  char recvBuf[4096] = "";
53
  char sendBuf[4096] = "";
54
  sockaddr_in addrFrom = {};
55
  int size = sizeof(addrFrom);
56
  while (true) {
57
    //4、接收数据
58
    nRecvNum = recvfrom(s, recvBuf, sizeof(recvBuf), 0, (sockaddr*)&addrFrom, &size);
59
    if (nRecvNum > 0) {
60
      cout << "ip: " << inet_ntoa(addrFrom.sin_addr) << "say: " << recvBuf << endl;
61
    }
62
    else {
63
      cout << "recvfrom error:" << WSAGetLastError() << endl;
64
      break;
65
    }
66
    cin >> sendBuf;
67
    nSendNum = sendto(s, sendBuf, strlen(sendBuf) + 1, 0, (sockaddr*)&addrFrom, size);
68
    if (SOCKET_ERROR == nSendNum) {
69
      cout << "sendto error: " << WSAGetLastError() << endl;
70
      break;
71
    }
72
    closesocket(s);
73
    WSACleanup();
74
  }
75

76
  //7、卸载库
77
  WSACleanup();
78
  return 0;
79
}

1
WSAStartup success
2
socket success
3
bind success