#include "stdafx.h"
#include <windows.h>
void main(int argc, char* argv[])
{
      HANDLE hDevice = CreateFile("C://S.txt",
            GENERIC_READ|GENERIC_WRITE,
            0,
            NULL,
            OPEN_EXISTING,
            FILE_ATTRIBUTE_NORMAL,
            NULL);
      if (hDevice == INVALID_HANDLE_VALUE)
      {
             printf("Failed to obtain file with %d error code !/n",GetLastError());
             return;
      }
      DWORD dwSize = GetFileSize(hDevice,NULL);
      printf("%d /n",dwSize);

      char chBuffer[10] = "5469";
      DWORD dwWriteSize = 0;
      BOOL bRet = WriteFile(hDevice,chBuffer,4,&dwWriteSize,NULL);
      if(bRet)
      {
             printf("write file success /n");
      }
      FlushFileBuffers(hDevice);   //將緩沖區數據寫入磁盤

      LONG IDistance = 0;
      DWORD dwPtr = SetFilePointer(hDevice,IDistance,NULL,FILE_BEGIN);  //調整文件指針到文件開頭
      DWORD dwReadSize = 0;
      bRet = ReadFile(hDevice,chBuffer,10,&dwReadSize,NULL);
      if (bRet)
      {
              printf("chbuffer is %s /n",chBuffer);
      }
      CloseHandle(hDevice);
      return ;
}

      char datain[101];
      FILE *fp_sys;
      fp_sys = fopen("要打開的文件名", "rb"); //第二個參數為打開方法，r代表讀，b代表二進制方式
      if(fp_sys == NULL) {
             AfxMessageBox("無法打開充值卡文件");