Conversion Between C++ and C Strings

While the conversion of a C string in a C++-string id done implicitly, you must explicitly request the conversion from a C++-string into a C string. str.copy() copies the content of a C++-string without the terminating \0 character. str.data() and str.c_str() includes the terminating null character.

Be careful with str.data() and str.c_str()

The return value of the two methods str.data() and std.c_str() is invalid, if you modify the str.

C versus C++-strings

// stringCversusC++.cpp
...
#include<string>
...

std::string str{"C++-String"};
str += " C-String";
std::cout << str;                 // C++-String C-String
const char* cString= str.c_str();
char buffer[10];
str.copy(buffer, 10);
str+= "works";
// const char* cString2= cString; // ERROR
std::string str2(buffer, buffer+10);
std::cout<< str2;                 // C++-String