string类的正确写法

[c++]代码库

#include <utility>
#include <string.h>
 
class String
{
 public:
  String()
    : data_(new char[1])
  {
    *data_ = '\0';
  }
 
  String(const char* str)
    : data_(new char[strlen(str) + 1])
  {
    strcpy(data_, str);
  }
 
  String(const String& rhs)
    : data_(new char[rhs.size() + 1])
  {
    strcpy(data_, rhs.c_str());
  }
  /* Delegate constructor in C++11
  String(const String& rhs)
    : String(rhs.data_)
  {
  }
  */
 
  ~String()
  {
    delete[] data_;
  }
 
  /* Traditional:
  String& operator=(const String& rhs)
  {
    String tmp(rhs);
    swap(tmp);
    return *this;
  }
  */
  String& operator=(String rhs) // yes, pass-by-value
  {
    swap(rhs);
    return *this;
  }
 
  // C++ 11
  String(String&& rhs)
    : data_(rhs.data_)
  {
    rhs.data_ = nullptr;
  }
 
  String& operator=(String&& rhs)
  {
    swap(rhs);
    return *this;
  }
 
  // Accessors
 
  size_t size() const
  {
    return strlen(data_);
  }
 
  const char* c_str() const
  {
    return data_;
  }
 
  void swap(String& rhs)
  {
    std::swap(data_, rhs.data_);
  }
 
 private:
  char* data_;
};