mystringimp.cpp

C++编成数据结构与程序设计方法 D.S.Malk编著

//Implementation file myStringImp.cpp
#include <iostream>
#include <iomanip>
#include <cstring>
#include <cassert>
#include "myString.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
    strcpy(strPtr, str);  //copy string into strPtr
}

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

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

   //Overload 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);
}

    //Overload 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;
}