string::c_str
Generates a null-terminated sequence of characters (c-string) with the same content as the string object and returns it as a pointer to an array of characters.
A terminating null character is automatically appended.
string::data
Returns a pointer to an array of characters with the same content as the string.
Notice that no terminating null character is appended
The null character ' \0 ' is used as a special character in a C-string to mark the end of the string but has no special meaning in an object of type string