http://knowledge.yahoo.com.tw/question/question?qid=1010042009900

gistfile1.h

#include <iostream>
#include <fstream>
#include <cstring>
// 緩衝區大小
#define BUFFERSIZE 4096
// 讀檔模式
#define READ (ios_base::in)
#define WRITE (ios_base::out | ios_base::app)
#define REWRITE (ios_base::out | ios_base::trunc)
// Integrated Development Environment
// Visual C++
using namespace std;
//
class CMyTxtFile
{
public:
	// 檔案名稱
	char* m_filename;
	// 建構子
	CMyTxtFile(const char* _filename);
	// 解構子
	~CMyTxtFile(void);
	// 複製檔案內容
	CMyTxtFile& operator =(const CMyTxtFile& _mytxtfile);
	// 在目的檔案尾端加入來源檔案的內容
	CMyTxtFile& operator +=(const CMyTxtFile& _mytxtfile);
	// 列印檔案內容
	void print(void);
	// 檔案是否存在
	bool is_exist(void);
private:
	// 檔案串流
	fstream m_file;
	// 暫存緩衝區的指標
	char* m_buffer;
	// 初始化記憶體
	void initmem(void* _buffer, size_t _size);
};
void main(int argc, char** argv)
{
	char *srcfn = "source.txt";
	char *desfn = "destination.txt";
	CMyTxtFile src(srcfn), des(desfn);
	cout<<src.m_filename<<"=>"<<(src.is_exist()?"Exist":"Doesnot exist")<<endl;
	cout<<des.m_filename<<"=>"<<(des.is_exist()?"Exist":"Doesnot exist")<<endl;
	src.print();
	des = src;
	des += src;
	des.print();
	system("PAUSE");
}
CMyTxtFile::CMyTxtFile(const char* _filename)
{
	this->m_file.clear();
	size_t _lenfilename = strlen(_filename);
	this->m_filename = new char[_lenfilename + 1];
	this->initmem((void*) this->m_filename, (_lenfilename + 1));
	strcpy(this->m_filename, _filename);
	this->m_buffer = NULL;
}
CMyTxtFile::~CMyTxtFile(void)
{
	this->m_file.clear();
	if ( this->m_filename != NULL )
	{
		delete [] this->m_filename;
		this->m_filename = NULL;
	}
}
CMyTxtFile& CMyTxtFile::operator =(const CMyTxtFile& _mytxtfile)
{
	if ( this != &_mytxtfile )
	{
		fstream _source;
		_source.open(_mytxtfile.m_filename, READ);
		if ( _source.is_open() )
		{
			this->m_file.open(this->m_filename, REWRITE);
			this->m_buffer = new char[BUFFERSIZE];
			size_t _readsize = BUFFERSIZE - 1;
			while ( !_source.eof() )
			{
				this->initmem((void*)this->m_buffer, BUFFERSIZE);
				_source.read(this->m_buffer, _readsize);
				this->m_file<<this->m_buffer;
			}
			delete [] this->m_buffer;
			this->m_buffer = NULL;
			this->m_file.close();
			_source.close();
		}
	}
	return (*this);
}
CMyTxtFile& CMyTxtFile::operator +=(const CMyTxtFile& _mytxtfile)
{
	if ( this != &_mytxtfile )
	{
		fstream _source;
		_source.open(_mytxtfile.m_filename, READ);
		if ( _source.is_open() )
		{
			this->m_file.open(this->m_filename, WRITE);
			this->m_buffer = new char[BUFFERSIZE];
			size_t _readsize = BUFFERSIZE - 1;
			while ( !_source.eof() )
			{
				this->initmem((void*)this->m_buffer, BUFFERSIZE);
				_source.read(this->m_buffer, _readsize);
				this->m_file<<this->m_buffer;
			}
			delete [] this->m_buffer;
			this->m_buffer = NULL;
			this->m_file.close();
			_source.close();
		}
	}
	return (*this);
}
void CMyTxtFile::print(void)
{
	cout<<"FileName= "<<(this->m_filename)<<endl;
	this->m_file.open(this->m_filename, READ);
	if ( this->m_file.is_open() )
	{
		this->m_buffer = new char[BUFFERSIZE];
		size_t _readsize = BUFFERSIZE - 1;
		while ( !this->m_file.eof() )
		{
			this->initmem((void*)this->m_buffer, BUFFERSIZE);
			this->m_file.read(this->m_buffer, _readsize);
			cout<<this->m_buffer;
		}
		cout<<endl;
		delete [] this->m_buffer;
		this->m_buffer = NULL;
		this->m_file.close();
	}
}
bool CMyTxtFile::is_exist(void)
{
	this->m_file.open(this->m_filename, READ);
	if ( this->m_file.is_open() )
	{
		this->m_file.close();
		return true;
	}
	return false;
}
void CMyTxtFile::initmem(void* _buffer, size_t _size)
{
	if ( _buffer != NULL )
	{
		memset((void*) _buffer, NULL, _size);
	}
}