如何将不同类型的数据放进一个数组里一起发送

场景： 不同类型的数据如bool、int等需要通过socket发送。

这里提供一个示例，关键部分：

const char *sendMsg = "0123456789";
int tLen=strlen(sendMsg);
int iLen=0;
char * pBuff= new char [100];
*(int*)(pBuff+iLen)= htonl(tLen);
  
iLen+=sizeof( int);
    
long mydata = 1234;
*(long*)(pBuff+iLen) = htonl(mydata);
iLen += sizeof(long);

 

示例中,client向server发送一段字符串、表示长度的int、表示其他数据的long

client.cpp

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
/*
将要发送的长度转成网络字节序，和数据一同放进发送缓冲区
int类型是怎么放进char[]里的？
int tLen=strlen(sendMsg);
int iLen=0;
char * pBuff= new char [100];
*(int*)(pBuff+iLen)= htonl(tLen);

*/

int MySend( int iSock, char * pchBuf, size_t tLen){
        int iThisSend;
        unsigned int iSended=0;
        if(tLen == 0)
               return(0);
        while(iSended<tLen){
              do{
                     iThisSend = send(iSock, pchBuf, tLen-iSended, 0);
              } while((iThisSend<0) && (errno==EINTR));
               if(iThisSend < 0){
                      return(iSended);
              }
              iSended += iThisSend;
              pchBuf += iThisSend;
       }
        return(tLen);
}
#define DEFAULT_PORT 6666
int main( int argc, char * argv[]){
    int connfd = 0;
    int cLen = 0;
    struct sockaddr_in client;
    if(argc < 2){
        printf(" Uasge: clientent [server IP address]\n");
        return -1;
    }
    client.sin_family = AF_INET;
    client.sin_port = htons(DEFAULT_PORT);
    client.sin_addr.s_addr = inet_addr(argv[1]);
    connfd = socket(AF_INET, SOCK_STREAM, 0);
    if(connfd < 0){
        printf("socket() failure!\n" );
        return -1;
    }

    if(connect(connfd, (struct sockaddr*)&client, sizeof(client)) < 0){
        printf("connect() failure!\n" );
        return -1;
    }
    ssize_t writeLen;
    const char *sendMsg = "0123456789";
    int tLen=strlen(sendMsg);
    printf("tLen:%d\n" ,tLen);
    int iLen=0;
    char * pBuff= new char [100];
    *(int*)(pBuff+iLen)= htonl(tLen);
    
    iLen+=sizeof( int);
    
    long mydata = 1234;
    //*(bool*)(pBuff+iLen) = htonl(mydata);
    *(long*)(pBuff+iLen) = htonl(mydata);
    iLen += sizeof(long);
    
    
    
    memcpy(pBuff+iLen,sendMsg,tLen);
    iLen+=tLen;
    writeLen= MySend(connfd, pBuff, iLen);
    if (writeLen < 0) {
       printf("write failed\n" );
       close(connfd);
       return 0;
    }
    else{
       printf("write sucess, writelen :%d, sendMsg:%s\n",writeLen,sendMsg);
    }
    close(connfd);
    return 0;
}

 

server.cpp

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <sys/wait.h>
#include <string.h>
#include <errno.h>
#include <iostream>

int MyRecv( int iSock, char * pchBuf, size_t tCount){
        size_t tBytesRead=0;
        int iThisRead;
        while(tBytesRead < tCount){
              do{
                     iThisRead = read(iSock, pchBuf, tCount-tBytesRead);
              } while((iThisRead<0) && (errno==EINTR));
              if(iThisRead < 0){
                      return(iThisRead);
              }else if (iThisRead == 0)
                      return(tBytesRead);
              tBytesRead += iThisRead;
              pchBuf += iThisRead;
       }
}
#define DEFAULT_PORT 6666
int main( int argc, char ** argv){
    int sockfd,acceptfd; /* 监听socket: sock_fd,数据传输socket: acceptfd */
    struct sockaddr_in my_addr; /* 本机地址信息 */
    struct sockaddr_in their_addr; /* 客户地址信息 */
    unsigned int sin_size, myport=6666, lisnum=10;
    if ((sockfd = socket(AF_INET , SOCK_STREAM, 0)) == -1) {
       perror("socket" );
       return -1;
    }
    printf("socket ok \n");
    my_addr.sin_family=AF_INET;
    my_addr.sin_port=htons(DEFAULT_PORT);
    my_addr.sin_addr.s_addr = INADDR_ANY;
    bzero(&(my_addr.sin_zero), 0);
    if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr )) == -1) {
        perror("bind" );
        return -2;
    }
    printf("bind ok \n");
    if (listen(sockfd, lisnum) == -1) {
        perror("listen" );
        return -3;
    }
    printf("listen ok \n");
    char recvMsg[10];
    sin_size = sizeof(my_addr);
    acceptfd = accept(sockfd,(struct sockaddr *)&my_addr,&sin_size);
    if (acceptfd < 0) {
       close(sockfd);
       printf("accept failed\n" );
       return -4;
    }
    ssize_t readLen = MyRecv(acceptfd, recvMsg, sizeof( int));
    if (readLen < 0) {
       printf("read failed\n" );
       return -1;
    }
    int len=( int)ntohl(*( int*)recvMsg);
    printf("len:%d\n",len);
    
    ssize_t mydatalen = MyRecv(acceptfd, recvMsg, sizeof(long));
    //long mydata=( long)ntohl(*( long*)recvMsg);
    long mydata=( long)ntohl(*( long*)recvMsg);
    printf("mydata : %d\n", mydata );
    
    readLen = MyRecv(acceptfd, recvMsg, len);
    if (readLen < 0) {
       printf("read failed\n" );
       return -1;
    }
    recvMsg[len]='\0';
    printf("recvMsg:%s\n" ,recvMsg);
    close(acceptfd);
    return 0;
  }

 

参考：

《后台开发核心技术与应用实践》例6.4