string, char*, const char*， int转换

string -> const char*

   string s = "abc";
   const char* c_s = s.c_str();

or

	const char* c_s = s.data();

const char* -> string

   const char* c_s = "abc";
   string s(c_s);

string -> char*

   string s = "abc";
   char* c;
   const int len = s.length();
   c = new char[len+1];
   strcpy(c,s.c_str());

char* -> string

   char* c = "abc";
   string s(c);

const char* -> char*

   const char* cpc = "abc";
   char* pc = new char[100];//足够长
   strcpy(pc,cpc);

char* -> const char*

   char* pc = "abc";
   const char* cpc = pc;

string -> int

	string row;
	int n = atoi(row.c_str());

int-> string

	stringstream stream;  
	string string_temp;
	stream<<int_temp;  
	string_temp=stream.str();   //此处也可以用 stream>>string_temp

char* -> int

char* a[];
int i = a[0] - '0';

int -> char*

char *str = (char*)i;