代码:

#include "stdafx.h"
#include <Windows.h>
#include <tchar.h>

#define MAX_SIZE 512

int EncodeQuoted(const unsigned char* pSrc, char* pDst, int nSrcLen, int nMaxLineLen);
int DecodeQuoted(const char* pSrc, unsigned char* pDst, int nSrcLen);

int _tmain(int argc, TCHAR *argv[])
{
       //MessageBox(NULL, L"a", L"a", MB_OK);
       BOOL bAction;
      // TCHAR tFileName = TEXT("a.txt");
      // TCHAR tWriteFile = "b.txt";
       char *pcBuffer = new char[MAX_SIZE];
       unsigned char *pDst = new unsigned char[MAX_SIZE];
       DWORD dwNumBytes = 0;
       DWORD dwFileSize = 0;
       HANDLE hFile = CreateFile(argv[1], GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
       if(hFile == INVALID_HANDLE_VALUE)
       {
             printf("file create error (error %d)\n", GetLastError());
             delete pcBuffer;
             delete pDst;
             pcBuffer = NULL;
             pDst = NULL;
             return 0;
       }
      // GetFileSize(hFile, &dwFileSize);
       bAction = ReadFile(hFile, pcBuffer, MAX_SIZE, &dwNumBytes, NULL);
       //printf("bAction is %d\n", bAction);
       if(!bAction)
       {
             printf("file read error(error %d)\n", GetLastError());
             delete pcBuffer;
             delete pDst;
             pDst = NULL;
             pcBuffer = NULL;
             CloseHandle(hFile);
             return 0;
       }
       dwFileSize = DecodeQuoted(pcBuffer, pDst, dwNumBytes);
       if(dwFileSize <= 0)
       {
             printf("dwFileSize is 0\n");
             return 0;
       }
       dwNumBytes = 0;
       delete pcBuffer;
       pcBuffer = NULL;
       CloseHandle(hFile);
       HANDLE hWriteFile = CreateFile(argv[2], GENERIC_WRITE, 0, NULL, CREATE_NEW, 0, NULL);
       if(hWriteFile == INVALID_HANDLE_VALUE)
       {
             printf("write file create error(error %d)\n", GetLastError());
             delete pDst;
             pDst = NULL;
             return 0;
       }
       bAction = WriteFile(hWriteFile, pDst, dwFileSize, &dwNumBytes, NULL);
       /*if(!bAction)
       {*/
             printf("write file write error(error %d)\n", GetLastError());
             delete pDst;
             pDst = NULL;
             CloseHandle(hWriteFile);
             return 0;
       //}
       //return 0;
}

int EncodeQuoted(const unsigned char* pSrc, char* pDst, int nSrcLen, int nMaxLineLen)
{
       int nDstLen; // 输出的字符计数
       int nLineLen; // 输出的行长度计数
       nDstLen = 0;
       nLineLen = 0;

       for (int i = 0; i < nSrcLen; i++, pSrc++)
       {
             // ASCII 33-60, 62-126原样输出，其余的需编码
             if ((*pSrc >= '!') && (*pSrc <= '~') && (*pSrc != '='))
             {
                   *pDst++ = (char)*pSrc;
                   nDstLen++;
                   nLineLen++;
             }
             else
             {
                   sprintf_s(pDst, MAX_SIZE, "=%02X", *pSrc);
                   pDst += 3;
                   nDstLen += 3;
                   nLineLen += 3;
             }
             // 输出换行？
             if (nLineLen >= nMaxLineLen - 3)
             {
                   sprintf_s(pDst, MAX_SIZE, "=\r\n");
                   pDst += 3;
                   nDstLen += 3;
                   nLineLen = 0;
             }
       }
       // 输出加个结束符
       *pDst = '\0';
       return nDstLen;
}

//Quoted-Printable解码很简单，将编码过程反过来就行了。 
int DecodeQuoted(const char* pSrc, unsigned char* pDst, int nSrcLen)
{
       int nDstLen; // 输出的字符计数
       int i;
       i = 0;
       nDstLen = 0;
       while (i < nSrcLen)
       {
             if (strncmp(pSrc, "=\r\n", 3) == 0) // 软回车，跳过
             {
                   pSrc += 3;
                   i += 3;
             }
             else
             {
                   if (*pSrc == '=') // 是编码字节
                   {
                         sscanf_s(pSrc, "=%02X", pDst);
                         pDst++;
                         pSrc += 3;
                         i += 3;
                   }
                   else // 非编码字节
                   {
                         *pDst++ = (unsigned char)*pSrc++;
                         i++;
                   }
                   nDstLen++;
             }
       }
       // 输出加个结束符
      // *pDst = '\0';
       return nDstLen;