Linux進程間通信：UDP

Server.c

#include <stdio.h>    
#include <stdlib.h>    
#include <unistd.h>    
#include <netinet/in.h>    
#include <arpa/inet.h>    
        
int main(void)    
{    
    //create socket    
    int fd = socket(AF_INET, SOCK_DGRAM, 0);    
    if(fd==-1)    
    {    
        perror("socket\n");    
        exit(-1);    
    }    
    printf("socket fd=%d\n",fd);    
        
    //build connection address    
    struct sockaddr_in addr;    
    addr.sin_family = AF_INET;    
    addr.sin_port = htons(6666);    
    addr.sin_addr.s_addr = inet_addr("127.0.0.1");    
        
    int r;    
    r = bind(fd,(struct sockaddr*)&addr,sizeof(addr));    
    if(r==-1)    
    {    
        perror("bind");    
        close(fd);    
        exit(-1);    
    }    
    printf("bind address successful!\n");    
    //accept or send message    
    char buf[255];    
    struct sockaddr_in from;    
    socklen_t len;    
    len = sizeof(from);    
    while(1)    
    {    
        r = recvfrom(fd,buf,sizeof(buf)-1,0,(struct sockaddr*)&from,&len);    
        if(r>0)    
        {    
            buf[r]=0;    
            printf("The message from %s is:%s\n",inet_ntoa(from.sin_addr),buf);    
        }    
        else
        {    
            break;    
        }    
    }    
    //close socket    
    close(fd);    
    return 0;    
}

Client.c

#include <stdio.h>    
#include <stdlib.h>    
#include <unistd.h>    
#include <string.h>    
#include <sys/socket.h>    
#include <netinet/in.h>    
#include <arpa/inet.h>    
        
int main(void)    
{    
    //create socket    
    int fd = socket(AF_INET,SOCK_DGRAM,0);    
    if(fd==-1)    
    {    
        perror("socket");    
        exit(-1);    
    }    
    printf("create socket OK!\n");    
    //create an send address    
    struct sockaddr_in addr={};    
    addr.sin_family = AF_INET;    
    addr.sin_port = htons(6666);    
    addr.sin_addr.s_addr=inet_addr("127.0.0.1");    
    //send the message to the specify address    
    int r;    
    char buf[255];    
    while(1)    
    {    
        r = read(0,buf,sizeof(buf)-1);    
        if(r<=0)    
            break;    
        sendto(fd,buf,r,0,(struct sockaddr*)&addr,sizeof(addr));    
    }    
    //close socket    
    close(fd);    
    return 0;    
}