1 long to char *
char basetime[32];
long mBaseTime;
mBaseTime = (long)time(NULL);
memset(basetime,0,sizeof(basetime));
ltoa(mBaseTime,basetime,10);
basetime：“1345636789”
2 char * to string
string strtime;
strtime= basetime;
3 分割字符
strtime = strtime.substr(5,5);
strtime：“36789”
4 char* to long
msgid = atol(strtime.c_str());