char * ,const char *,string的相互转化

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;