[ZZ] C++ char*，const char*，string的相互转换

_{1. string转const char*}

 string s = "abc";

constchar* c_s = s.c_str();

2. const char*转string

   直接赋值即可

constchar* c_s = "abc";
string s(c_s);

 3. string转char*

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

 4. char*转string

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

 5. const char*转char*

constchar* cpc = "abc";
char* pc = newchar[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;