用文件的读写和string作为临时存储区复制图片文件

读写用_wfopen(),所以都出来的是双字节的，所以涉及到字节转换，把都出来的数据转换成单字节然后再存在String类对象里面，写入新的文件时要重新转换成双字节再写入。

代码如下：

#include <iostream>
#include <windows.h>
#include <string>

using namespace std;

void Wchar_tToString(string& szDst, wchar_t *wchar)
{
	wchar_t * wText = wchar;
	DWORD dwNum = WideCharToMultiByte(CP_OEMCP,NULL,wText,-1,NULL,0,NULL,FALSE);// WideCharToMultiByte的运用
	char *psText;  // psText为char*的临时数组，作为赋值给std::string的中间变量
	psText = new char[dwNum];
	WideCharToMultiByte (CP_OEMCP,NULL,wText,-1,psText,dwNum,NULL,FALSE);// WideCharToMultiByte的再次运用
	szDst = psText;// std::string赋值
	delete []psText;// psText的清除
}

void StringToWchar_t(wchar_t * wchar,string str)
{
	int  len = 0;
	len = str.length();
	int unicodeLen = MultiByteToWideChar(CP_ACP,NULL,str.c_str(),-1,NULL,0);
	wchar_t *  pUnicode;  
	pUnicode = new  wchar_t[unicodeLen+1];  
	memset(pUnicode,0,(unicodeLen+1)*sizeof(wchar_t));  
	MultiByteToWideChar( CP_ACP,
			0,
			str.c_str(),
			-1,
			(LPWSTR)wchar,
			unicodeLen );   
	delete  pUnicode; 
}

int main()
{
	FILE * fp1 = _wfopen(L"D:\\test.jpg",L"rb+");
	if (fp1 == NULL)
	{
		cout << "what the fuck?" << endl;
	}
	string s;
	wchar_t temp[100] = {0};
	while(fread(temp,sizeof(wchar_t),100,fp1))
	{
		string t;
		Wchar_tToString(t,temp);
		s += t;
	}
	//cout << s << endl;
	fclose(fp1);

	FILE * fp2 = _wfopen(L"D:\\test2.jpg",L"wb+");
	int n = s.length();
	int l = n % 100;
	int count = n / 100;
	int index1 = 0;
	int index2 = 99;

	for (int i = 0;i < count;i ++)
	{
		wchar_t s1[100] = {0};
		string s2 = s.substr(index1,index2);
		StringToWchar_t(s1,s2);
		index1 += 100;
		index2 += 100;
		//fseek(fp2,0,SEEK_END);
		fwrite(s1,sizeof(wchar_t),100,fp2);
		//fflush(fp2);
		//fputws(s1,fp2);
	}
	wchar_t *s3 = new wchar_t[l];
	index2 = index2 - 100 + l;
	string s4 = s.substr(index1,index2);
	StringToWchar_t(s3,s4);
	//fseek(fp2,0,SEEK_END);
	fwrite(s3,sizeof(wchar_t),l,fp2);
	fclose(fp2);
	return 0;
}