newstringimp.cpp

来自「这是学习《Data Structures Using C++》」· C++ 代码 · 共 117 行

//Implementation file newString.cpp
#include <iostream>
#include <iomanip>
#include <cstring>
#include <cassert>
#include "newString.h"

using namespace std;


      //constructor: conversion from the char string to newString
newString::newString(const char *str) 
{
   strLength = strlen(str);
   strPtr = new char[strLength+1]; 	//allocate memory to store 
  									//the char string
   assert(strPtr != NULL);
   strcpy(strPtr,str);				//copy the string into strPtr
}

	//default constructor to store the null string
newString::newString() 
{
		strLength = 0;
		strPtr = new char[1];
		assert(strPtr != NULL);
		strcpy(strPtr,"");
}

newString::newString(const newString& rightStr)  //copy constructor
{
	strLength = rightStr.strLength;
	strPtr = new char[strLength + 1];
	assert(strPtr != NULL);
	strcpy(strPtr, rightStr.strPtr);
}

newString::~newString()  //destructor
{
	delete [] strPtr;
}

//Overload the assignment operator
const newString& newString::operator=(const newString& rightStr)
{
	if(this != &rightStr) //avoid self-copy
	{
		delete [] strPtr;
		strLength = rightStr.strLength;
		strPtr = new char[strLength + 1];
		assert(strPtr != NULL);
		strcpy(strPtr, rightStr.strPtr);
	}
	return *this; 
}

char& newString::operator[] (int index)
{
	assert(0 <= index && index < strLength);
	return strPtr[index];
}

const char& newString::operator[](int index) const
{
	assert(0 <= index && index < strLength);
	return strPtr[index];
}

		//Overloads the relational operators
bool newString::operator==(const newString& rightStr) const
{
	return(strcmp(strPtr, rightStr.strPtr) == 0);
}

bool newString::operator<(const newString& rightStr) const
{
	return(strcmp(strPtr, rightStr.strPtr) < 0);
}

bool newString::operator<=(const newString& rightStr) const
{
	return(strcmp(strPtr, rightStr.strPtr) <= 0);
}

bool newString::operator>(const newString& rightStr) const
{
	return(strcmp(strPtr, rightStr.strPtr) > 0);
}

bool newString::operator>=(const newString& rightStr) const
{
	return(strcmp(strPtr, rightStr.strPtr) >= 0);
}

bool newString::operator!=(const newString& rightStr) const
{
	return(strcmp(strPtr, rightStr.strPtr) != 0);
}

//Overloads the stream insertion operator << 
ostream& operator<<(ostream& osObject, const newString& str)
{
	osObject<<str.strPtr;
	return osObject;
}

//Overload the stream extraction operator >> 
istream& operator>>(istream& isObject, newString& str)
{
	char temp[81];

	isObject>>setw(81)>>temp;
	str = temp;
	return isObject;
}