mystring.cpp

我自己编写的字符串类

//MyString.cpp--类的实现文件

#include "MyString.h"

CMyString::CMyString()
{
	m_len=0;
	m_size=0;
	m_pstr=NULL;
}

CMyString::~CMyString()
{

}

CMyString::CMyString(char *str)
{
    if(str==NULL)
	{
		m_len=0;
		m_size=0;
		m_pstr=NULL;
	}
	else
	{
		m_len=strlen(str);
		m_size=m_len+1;
		m_pstr=new char[m_size];
		if(m_pstr!=NULL)
			strcpy(m_pstr,str);
	}	
}

CMyString::CMyString(CMyString &str)
{
	if(str.m_pstr==NULL)
	{
		m_len=0;
		m_size=0;
		m_pstr=NULL;
	}
	else
	{
		m_pstr=str.m_pstr;
		m_len=str.m_len;
		m_size=str.m_size;
	}
}

const char * CMyString::Convert()
{
	if(this->m_pstr==NULL)
		return NULL;
	else
		return (const char *)this->m_pstr;
}

CMyString & CMyString::operator =(char *str)
{
	if(str==NULL)
	{
		m_len=0;
		m_size=0;
		m_pstr=NULL;
	}
	else
	{
		m_len=strlen(str);
		m_size=m_len+1;
		m_pstr=new char[m_size];
		if(m_pstr!=NULL)
			strcpy(m_pstr,str);
	}
	return *this;
}

CMyString & CMyString::operator =(CMyString &str)
{
	if(str.m_pstr==NULL)
	{
		m_len=0;
		m_size=0;
		m_pstr=NULL;
	}
	else
	{
		m_pstr=str.m_pstr;
		m_len=str.m_len;
		m_size=str.m_size;
	}
	return *this;
}

char * CMyString::operator +(char *str)
{
	char *newstr=new char[this->m_len+strlen(str)+1];
	if(newstr!=NULL)
		strcpy(newstr,this->m_pstr);
	if(str!=NULL)
		strcat(newstr,str);
	return newstr;	
}

char* CMyString::operator +(CMyString &str)
{
    char * newstr=new char[this->m_len+str.m_len+1];
    if(newstr!=NULL)
		strcpy(newstr,this->m_pstr);
	if(str.m_pstr!=NULL)
		strcat(newstr,str.m_pstr);
	return newstr;
}

int CMyString::Compare(char *cmpstr)
{
	 return strcmp(m_pstr,cmpstr);
}

int CMyString::Compare(CMyString &cmpstr)
{
	 return strcmp(m_pstr,cmpstr.m_pstr);
}

int CMyString::operator <(char *cmp)
{
	return Compare(cmp)<0;
}

int CMyString::operator <(CMyString &cmp)
{
	return Compare(cmp)<0;
}

int CMyString::operator >(char *cmp)
{
	return Compare(cmp)>0;
}

int CMyString::operator >(CMyString &cmp)
{
	return Compare(cmp)>0;
}

int CMyString::operator ==(char *cmp)
{
	return Compare(cmp)==0;
}

int CMyString::operator ==(CMyString &cmp)
{
	return Compare(cmp)==0;
}

char CMyString::operator [](int i)
{
	if(i<0)
	{
		return m_pstr[0]; 
    }
    if(i>m_len)
	{
		return m_pstr[m_len];
	}
    else
		return m_pstr[i];
}