数据类型转换(char * ,char [] ,string ,int char)

1.char[]  to string

 char   buf[]   =   "abcd";
 string   str;
 str.assign(&buf[0], &buf[strlen(buf)]);

2.string to char *

 string strDate = "test";
 char * cData = const_cast<char *> (strDate.c_str());