c++ - c_str implemenation for String class -

i reading chapter 12 in accelerated c++ book on implementing string class.

there end-of-chapter question implement c_str() function. looking ideas.

here have far:

my first attempt heap allocate char * , return it. result in memory leaks:

cost char * c_star() const {    //cannot reference result later    //causes memory leaks     char* result = new char[data.size() + 1];    std::copy(data.begin(), data.end(), result);    result[data.size()] = '\0';    return result; } 

here attempt:

const char* c_str() const {     //obviously incorrect implementation not nul('\0') terminated.     return &data[0]; } 

i cannot push_back '\0' data since should not change data.

here spec:

returns pointer array contains null-terminated sequence of characters (i.e., c-string) representing current value of string object.

here book implementation: (renamed str). internally, characters stored in vector implementation (vec).

class str {     public:        .        .        .      private:         vec<char> data; }; 

base on comments, implemented str class making sure there nul('\0') @ end of every string. instead of vector, store data in character array:

class str {     public:         typedef char* iterator;         typedef const char* const_iterator;         .         .         .         //c_str return nul terminated char array         const char* c_str() const { return str_beg; };         //c_str , data same implementation make sure there nul         //at end         const char* data() const { return str_beg; };         .         .         .      private:         iterator str_beg;         .         .         . };