[C++]仿java.lang.String功能的字符串类[原]

BwString.h：

#pragma once
#include <assert.h>

namespace BW_Util{

    class BwString;

    //重载符 + const char*

    BwString operator+(BwString& str, const char* pStr);

    //重载符 + const wchar_t*

    BwString operator+(BwString& str, const wchar_t* pStr);

    //重载符 + EcpString& str

    BwString operator+(BwString& str1, BwString& str2);

    class BwString
    {
    public:
        BwString(void);

        BwString(const char * pStr);

        BwString(const wchar_t * pStr);

        //构造一个由pStr1和pStr2连接起来的对象。例如L"abc"和L"def"连接起来为L"abcdef"

        BwString(const wchar_t * pStr1, const wchar_t * pStr2);

        //构造一个由pStr1和pStr2连接起来的对象。例如"abc"和"def"连接起来为L"abcdef"

        BwString(const char * pStr1, const char * pStr2);

        //构造一个由pStr1和pStr2连接起来的对象。例如L"abc"和"def"连接起来为L"abcdef"

        BwString(const wchar_t * pStr1, const char * pStr2);

        //构造一个由pStr1和pStr2连接起来的对象。例如"abc"和L"def"连接起来为L"abcdef"

        BwString(const char * pStr1, const wchar_t * pStr2);

        ~BwString(void);

        //重载符 + const char*

        BwString friend BW_Util::operator+(BwString& str, const char* pStr);

        //重载符 + const wchar_t*

        BwString friend BW_Util::operator+(BwString& str, const wchar_t* pStr);

        //重载符 + EcpString& str

        BwString friend BW_Util::operator+(BwString& str1, BwString& str2);

        //重载符 = const char*

        wchar_t* operator=(const char* pStr);

        //重载符 = const wchar_t*

        wchar_t* operator=(const wchar_t* pStr);

        //重载符 = EcpString& str

        BwString& operator=(BwString& str);

        //重载符 += const char*

        wchar_t* operator+=(const char* pStr);

        //重载符 += const wchar_t*

        wchar_t* operator+=(const wchar_t* pStr);

        //重载符 += EcpString& str

        BwString& operator+=(BwString& str);

        //重载符 < EcpString& str：比较两个字符串的大小。

        bool operator<(BwString& str);

        //重载符 > EcpString& str：比较两个字符串的大小。

        bool operator>(BwString& str);

        //重载符 (wchar_t*)

        operator wchar_t*();

        //字符串长度

        int Length();
    private:

        //指向宽字符串的指针

        wchar_t *pw;

        //当前字符串的长度（不含结束符0）

        int currLen;

        //扩容量

        int growSize;

        //字符串的容量

        int maxLen;

        //初始化基本的成员变量

        void init();

        //在当前字符串后追加新字符串

        template <class T> wchar_t* Append(const T* pVal);

        //计算指定char*/wchar_t*的长度（不包括结束符）。这里定义为私有是因为其只对char*、wchar_t*和int*有效

        template <class T> int CharsCount(const T* pStr);
    };

}

BwString.cpp:

#include "BwString.h"
#include <string>

void BW_Util::BwString::init()
{
    currLen = 0;
    maxLen = 3;
    growSize = 3;
    pw = (wchar_t*)calloc(maxLen, sizeof(wchar_t));
}

BW_Util::BwString::BwString(void)
{
    init();
}

BW_Util::BwString::BwString( const char * pStr )
{
    init();
    (*this) = pStr;
}

BW_Util::BwString::BwString( const wchar_t * pStr )
{
    init();
    (*this) = pStr;
}

BW_Util::BwString::BwString( const wchar_t * pStr1, const wchar_t * pStr2 )
{
    init();
    (*this) = pStr1;
    Append(pStr2);
}

BW_Util::BwString::BwString( const char * pStr1, const char * pStr2 )
{
    init();
    (*this) = pStr1;
    Append(pStr2);
}

BW_Util::BwString::BwString( const wchar_t * pStr1, const char * pStr2 )
{
    init();
    (*this) = pStr1;
    Append(pStr2);
}

BW_Util::BwString::BwString( const char * pStr1, const wchar_t * pStr2 )
{
    init();
    (*this) = pStr1;
    Append(pStr2);
}

BW_Util::BwString::~BwString(void)
{
    if(pw)
    {
        free(pw);
        pw = 0;
    }
}

int BW_Util::BwString::Length()
{
    return currLen;
}

wchar_t* BW_Util::BwString::operator=(const char* pStr )
{
    memset(pw, '\0', maxLen);
    currLen = 0;
    Append(pStr);
    return pw;
}

wchar_t* BW_Util::BwString::operator=( const wchar_t* pStr )
{
    memset(pw, '\0', maxLen);
    currLen = 0;
    Append(pStr);
    return pw;
}

BW_Util::BwString& BW_Util::BwString::operator=( BwString& str )
{
    //此时调用了重载符：char* EcpString::operator=(const char* pStr )

    (*this) = str.pw;
    return str;
}

BW_Util::BwString::operator wchar_t*()
{
    return pw;
}

wchar_t* BW_Util::BwString::operator+=( const char* pStr )
{
    Append(pStr);
    return (*this);
}

wchar_t* BW_Util::BwString::operator+=( const wchar_t* pStr )
{
    Append(pStr);
    return (*this);
}

BW_Util::BwString& BW_Util::BwString::operator+=( BwString& str )
{
    Append(str.pw);
    return (*this);
}

template <class T>
wchar_t* BW_Util::BwString::Append( const T* pVal )
{
    int len = CharsCount(pVal);
    if(len + currLen >= maxLen )
    {
        while( len + currLen >= maxLen)
        {
            maxLen += growSize;
        }
        wchar_t * pwTemp = (wchar_t*)calloc(maxLen, sizeof(wchar_t));
        memcpy(pwTemp, pw, currLen * sizeof(wchar_t));
        free(pw);
        pw = pwTemp;
    }
    
    for(int i=currLen, j = 0; i<len + currLen; i++, j++)
    {
        pw[i] = pVal[j];
    }

    currLen += len;

    return pw;
}

bool BW_Util::BwString::operator<( BwString& str )
{
    for(int i=0; i<currLen; i++)
    {
        if(pw[i] < str.pw[i])
            return true;
    }
    return false;
}

bool BW_Util::BwString::operator>( BwString& str )
{
    for(int i=0; i<currLen; i++)
    {
        if(pw[i] > str.pw[i])
            return true;
    }
    return false;
}

template <class T>
int BW_Util::BwString::CharsCount( const T* pStr )
{
    int i=0;
    for(; pStr[i]; i++)
    {}
    return i;
}

BW_Util::BwString BW_Util::operator+( BwString& str, const char* pStr )
{
    //这里直接调用构造函数，而不是实例一个对象后在返回这个对象，是为了避免调用拷贝构造函数

    return BwString(str.pw, pStr);
}

BW_Util::BwString BW_Util::operator+( BwString& str, const wchar_t* pStr )
{
    return BwString(str.pw, pStr);
}

BW_Util::BwString BW_Util::operator+( BwString& str1, BwString& str2 )
{
    return BwString(str1.pw, str2.pw);
}


测试代码：

void _BwWString_Test()
{
    //宽字符串测试

    BwString str = L"wangaiguo";
    wcout << "str=" << (wchar_t*)str << endl;    //str=wangaiguo


    BwString str2;
    str2 = L"wuqian ";
    wcout << "str2=" << (wchar_t*)str2 << endl;    //str2=wuqian


    str += L" nanjing ";
    wcout << "str=" << (wchar_t*)str << endl;    //str=wangaiguo nanjing


    str2 += str;
    wcout << "str2=" << (wchar_t*)str2 << endl;    //str2=wuqian wangaiguo nanjing


    BwString str3, str4;
    str3 = str3 + L"escarp";
    wcout << "str3=" << (wchar_t*)str3 << endl;    //str3=escarp


    str4 = str + str3;
    wcout << "str4=" << (wchar_t*)str4 << endl;    //str4=wangaiguo nanjing escarp


    str = str2;
    wcout << "str=" << (wchar_t*)str << endl;    //str=wuqian wangaiguo nanjing

}

void _BwString_Test()
{
    //普通字符串测试

    BwString str = "wangaiguo";
    wcout << "str=" << (wchar_t*)str << endl;    //str=wangaiguo


    BwString str2;
    str2 = "wuqian ";
    wcout << "str2=" << (wchar_t*)str2 << endl;    //str2=wuqian


    str += " nanjing ";
    wcout << "str=" << (wchar_t*)str << endl;    //str=wangaiguo nanjing


    str2 += str;
    wcout << "str2=" << (wchar_t*)str2 << endl;    //str2=wuqian wangaiguo nanjing


    BwString str3, str4;
    str3 = str3 + "escarp";
    wcout << "str3=" << (wchar_t*)str3 << endl;    //str3=escarp


    str4 = str + str3;
    wcout << "str4=" << (wchar_t*)str4 << endl;    //str4=wangaiguo nanjing escarp


    str = str2;
    wcout << "str=" << (wchar_t*)str << endl;    //str=wuqian wangaiguo nanjing

}