Using C++

create a simple str class that mimic the functionality of the std::stringclass. To keep things civilized, I have taken the liberty of implementing part of the str class. You are asked to complete the rest of the functions.

Task

Please implement your functions in the str.cpp class.

-------------------------------------------------------------------------------------------------------------------------------------------

// str.h  #ifndef __str_h__ #define __str_h__  #include  #include  #include   using namespace std; class str { protected: char* _buf; // pointer to the underlying storage  int _n; // size of the buffer  public: // constructors of various forms  str(); str(int n); str(char ch); str(const char* c_str); // lets not forget the destructor  ~str(); // inline functions for finding length info of the str  inline const int& length() const { return _n; } inline bool is_empty() const { return length() == 0; } // index operators  char& operator[](int i) { return _buf[i]; } const char& operator[](int i) const { return _buf[i]; } // TODO 1. You need to implement the assignment operator  const str& operator=(const str& s); // TODO 2. You need to implement the + operator concatenates two str  friend str operator+(const str& a, const str& b); friend ostream& operator<<(ostream& os, const str& s); friend istream& operator>>(istream& is, str& s); }; #endif 

---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Meanwhile the str.cpp file looks like

// str.cpp  #include "str.h"  str::str() : _n(0), _buf(0) {} str::str(int n) : _n(n) { _buf = new char[_n]; } str::str(char ch) : _n(1) { _buf = new char[_n]; _buf[0] = ch; } str::str(const char* c_str) { _n = strlen(c_str); _buf = new char[_n]; for (int i=0; i<_n; ++i) _buf[i]=c_str[i]; } str::~str() { if (_buf) delete [] _buf; } ostream& operator<<(ostream& os, const str& s) { if (!s.is_empty()) { for (int i=0; i<s.length(); ++i) { cout << s[i]; } } else cout << "[null str]"; return os; } istream& operator>>(istream& is, str& s) { char ch; do { ch = is.get(); if (ch == ' ' || ch == ' ') break; s = s + ch; } while(true); return is; } // 1. TODO - assignment operator  // 2. TODO - concatenation operator 

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

// main.cpp  #include "str.h"  int main() { str s1; cout << s1 << endl; str s2("Hello"); cout << s2 << endl; str s3("World"); str s4 = s2 + " " + s3; cout << s4 << endl; str s5, s6; cin >> s5 >> s6; cout << s5 << ' ' << s6; return 0; }