Accelerated 12 Str (Making class objects act like values)

Vec.h
see note 11

Str.h

#ifndef GUARD_Str_h#define GUARD_Str_h// Str.h#include <cstring>  //strlen()#include <algorithm>#include <iostream>#include "Vec.h"class Str {    friend  std::istream& operator>>(std::istream&, Str&);    public:        typedef Vec<char>::size_type size_type;        // default constructor; creat an empty Str        Str(): p_c_str(NULL), p_data(NULL) { }        // create a Str containing n copies of c        Str(size_type n, char c): chars(n, c), p_c_str(NULL), p_data(NULL) { }         // create a Str from a null-terminated array of char        Str(const char* cp): p_c_str(NULL), p_data(NULL) {            std::copy(cp, cp + std::strlen(cp), std::back_inserter(chars));        }        ~Str() {            if (p_c_str)                 delete[] p_c_str;            if (p_data)                delete[] p_data;        }        // create a Str from the range denoted by iterators b and e        template <class In> Str(In b, In e): p_c_str(NULL), p_data(NULL) {            std::copy(b, e, std::back_inserter(chars));        }        char& operator[] (size_type i) { return chars[i]; }        const char& operator[] (size_type i) const { return chars[i]; }        size_type size() const { return chars.size(); }        Str& operator+=(const Str& s) {            std::copy(s.chars.begin(), s.chars.end(), std::back_inserter(chars));            return *this;        }        char* c_str();        char* data();    private:        Vec<char> chars;        char* p_c_str;        char* p_data;};std::ostream& operator<<(std::ostream&, const Str&);Str operator+(const Str&, const Str&);#endif

Str.cpp

// source file Str-related#include <cctype>#include "Str.h"using std::istream; using std::ostream;istream& operator>>(istream& in, Str& s) {    // obliterate existing value(s)    s.chars.clear();    char c;    while(in.get(c) && isspace(c))        ;    if (in) {        do s.chars.push_back(c);        while (in.get(c) && !isspace(c));        if (in)            in.unget();    }    return in;}ostream& operator<<(ostream& out, const Str& s) {    for (Str::size_type i = 0; i != s.size(); ++i)        out << s[i];    return out;}Str operator+(const Str& s, const Str& t) {    Str r = s;    return r += t;}char* Str::c_str() {    if (p_c_str)        delete[] p_c_str;    p_c_str = new char[chars.size() + 1];    for (size_type i = 0; i != chars.size(); ++i)         p_c_str[i] = chars[i];    p_c_str[chars.size()] = '\0';    return p_c_str;}char* Str::data() {    if (p_data)        delete[] p_data;    p_data = new char[chars.size()];    for (size_type i = 0; i != chars.size(); ++i)         p_data[i] = chars[i];    return p_data;}

main.cpp

#include <iostream>#include <string>#include "Str.h"using std::cout;    using std::endl;    using std::string;int main() {    Str s;    Str k = "kang";    Str r("rui");    Str h = "huan";    string str = "lzj";    Str l(str.begin(), str.end());    s = k + r + h;    cout << s << endl;    cout << s.size() << endl;    cout << l << endl;    char* cp = l.c_str();    char* cp2 = l.data();    char ch = *cp;    cout << ch << endl;    cout << cp << endl;    cout << sizeof(cp) << endl;    cout << cp2 << endl;    cout << sizeof(cp2) << endl;    cout << cp[1] << endl;}