class file_send
{
      public:
             SOCKET send_s; //The socket that used for sending which is established previously
             char * filename; //The full path of the file that the client requested
             void send_file()
             {
                 percentage=0;
                 FILE * pFile=fopen(filename,"rb");                 
                 fseek(pFile,0,SEEK_END);
                 flen=ftell(pFile);
                 cout<<"File length is :"<<flen<<endl;
                 rewind(pFile);
                 partsnum=flen/BUF_LEN+1;
                 send(send_s,(char *)(&partsnum),sizeof(partsnum),0);
                 cout<<"File parts num:"<<partsnum<<endl;
                 cout<<"File name:"<<filename<<endl;
                 str=new char[BUF_LEN];
                 int i;
                 if(partsnum>1)
                 {
                     plen=BUF_LEN;
                 }
                 for(i=0;i<partsnum;i++)
                 {
                     if(i==(partsnum-1))
                     {
                         plen=flen%BUF_LEN;
                     }
                     fread(str,1,BUF_LEN,pFile);
                     send(send_s,(char *)(&plen),sizeof(plen),0);
                     send(send_s,str,plen,0);
                     if(percentage!=(i*100)/partsnum)
                     {
                         percentage=(i*100)/partsnum;
                         cout<<percentage<<"\%complete!"<<endl;
                     }
                     //cout<<"File parts send:"<<i<<endl;
                     //cout<<"File parts length is:"<<plen<<endl;
                     //cout<<"Read content is:"<<str<<endl; 
                 }
                 fclose(pFile);
             }
      private:
             int flen,plen,partsnum,percentage;
             char * str;
};

接收端：

class file_rev
{
      public:
             SOCKET rev_s;
             char * filename;
             void rev_file()
             {
                 FILE * fn=fopen(filename,"wb");
                 recv(rev_s,(char *)(&partsnum),sizeof(partsnum),0);
                 cout<<"File parts num:"<<partsnum<<endl;
                 int i;
                 for(i=0;i<partsnum;i++)
                 {
                      recv(rev_s,(char *)(&flen),sizeof(flen),0); 
                      buf=new char[flen];
                      recv(rev_s,buf,flen,0);
                      //cout<<"File parts received:"<<i<<endl;
                      //cout<<"File parts length:"<<flen<<endl;               
                      fwrite(buf,1,flen,fn);
                 }
                 fclose(fn);
             }
      private:
             int flen,plen,partsnum;
             char * buf;
};