char*,const char*和string的相互转换（转）

1. string转const char*
   string s = “abc”;
   const char* c_s = s.c_str();
2. const char*转string
   直接赋值即可
   const char* c_s = “abc”;
   string s(c_s);
3. string转char*
   string s = “abc”;
   char* c;
   const int len = s.length();
   c = new char[len+1];
   strcpy(c,s.c_str());
4. char*转string
   char* c = “abc”;
   string s(c);
5. const char*转char*
   const char* cpc = “abc”;
   char* pc = new char[100];//足够长
   strcpy(pc,cpc);
6. char*转const char*
   直接赋值即可
   char* pc = “abc”;
   const char* cpc = pc;