linux udp通信程序

服务端程序为：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>

int main()
{
struct sockaddr_in srvAddr;
bzero(&srvAddr,sizeof(srvAddr));
srvAddr.sin_family = AF_INET;
srvAddr.sin_addr.s_addr = htonl(INADDR_ANY);
srvAddr.sin_port = htons(8888);
int srvAddrLen = sizeof(srvAddr);

int iSock = socket(AF_INET, SOCK_DGRAM, 0); // udp
bind(iSock, (struct sockaddr *)&srvAddr, sizeof(srvAddr));

while(1)
{
getchar(); // 卡住
char szBuf[1024] = {0};
recvfrom(iSock, szBuf, sizeof(szBuf) - 1, 0, (struct sockaddr *)&srvAddr, (socklen_t*)&srvAddrLen); // 注意: 这里用srvAddr是不好的，应该用cliAddr,表示对方地址
printf("msg from client [%s]\n", szBuf);
}

close(iSock);
return 0;
}

        客户端程序为：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>

int main()
{
struct sockaddr_in srvAddr;
bzero(&srvAddr, sizeof(srvAddr));
srvAddr.sin_family = AF_INET;
srvAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
srvAddr.sin_port = htons(8888);

int iSock = socket(AF_INET, SOCK_DGRAM, 0); // udp
   int i = 0;
while(1)
{
       printf("press enter to send data\n");
       getchar(); // 卡住
       char szBuf[32] = {0};
snprintf(szBuf, sizeof(szBuf), "hello %d", ++i);
sendto(iSock, szBuf, strlen(szBuf) + 1, 0, (struct sockaddr *)&srvAddr, sizeof(srvAddr));
}

   close(iSock);
return 0;
}
        makefile为：
all: server client

server: server.o
g++ -o server server.o

client: client.o
g++ -o client client.o

server.o: server.cpp
g++ -c server.cpp

client.o:client.cpp
g++ -c client.cpp

clean:
rm -f server client *.o

编译并运行，先启动服务端，然后启动客户端。因为程序中有getchar卡住，所以我们需要按enter键来控制客户端的发送和服务端的接受。
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原文：https://blog.csdn.net/stpeace/article/details/73699517

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