base64處理類

 base64是日常開發中經常使用的編碼方式，在.net,java甚至php中都有簡單的類庫或函數直接調用，唯獨c++中沒有可用的資源，沒有辦法，誰讓c++靈活呢，自己動手開發一個吧。

base64的原理很簡單，無須贅述，google一下，一大堆，但是好用的有算法精妙的代碼着實不多，自己動腦又太費神，找個成熟的其他語言的類翻譯一下吧，嗯，c#的語法與c++很相似，ok，抄襲一下。不再囉嗦，直接看代碼吧。

 

頭文件代碼如下（base64.h）：

#if !defined(AFX_BASE641_H__D58B5645_B438_43B6_8844_457ADE5F85CC__INCLUDED_)
#define AFX_BASE641_H__D58B5645_B438_43B6_8844_457ADE5F85CC__INCLUDED_

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

class CBase64 
{
public:
 static int ToBase64String(char* & pOut,char * pIn,int nLen);
 static int FromBase64String(char * & pOut,char * pIn);
 CBase64();
 virtual ~CBase64();
protected:
 static int CalculateOutputLength(int inputLength);
 static int ConvertToBase64(char* outChars, char* inData, int length);
 static char char2sixbit(char c);
};

#endif // !defined(AFX_BASE641_H__D58B5645_B438_43B6_8844_457ADE5F85CC__INCLUDED_)

cpp文件代碼如下：

// Base641.cpp: implementation of the CBase64 class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "Base64.h"
#include <string.h>
//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////
static char base64Table[]="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
CBase64::CBase64()
{

}

CBase64::~CBase64()
{

}
int CBase64::CalculateOutputLength(int inputLength)
{
      int num1 = (inputLength / 3) * 4;
      num1 += ((inputLength % 3) != 0) ? 4 : 0;
      if (num1 == 0)
      {
            return num1;
      }
      int num2 = num1 / 0x4c;
      if ((num1 % 0x4c) == 0)
      {
            num2--;
      }
      return (num1 + (num2 * 2));
}
int CBase64::ConvertToBase64(char* outChars, char* inData, int length)
{
   int num1 = length % 3;
   int num2 = length - num1;
   int num3 = 0;
   int num4 = 0;
   char* chRef1 = base64Table;
     
 int num5 = 0;
 while (num5 < num2)
 {
   
    outChars[num3] = chRef1[(inData[num5] & 0xfc) >> 2];
    outChars[num3 + 1] = chRef1[((inData[num5] & 3) << 4) | ((inData[num5 + 1] & 240) >> 4)];
    outChars[num3 + 2] = chRef1[((inData[num5 + 1] & 15) << 2) | ((inData[num5 + 2] & 0xc0) >> 6)];
    outChars[num3 + 3] = chRef1[inData[num5 + 2] & 0x3f];
    num3 += 4;
    num5 += 3;
 }
 num5 = num2;

 switch (num1)
 {
    case 1:
    break;

    case 2:
    outChars[num3] = chRef1[(inData[num5] & 0xfc) >> 2];
    outChars[num3 + 1] = chRef1[((inData[num5] & 3) << 4) | ((inData[num5 + 1] & 240) >> 4)];
    outChars[num3 + 2] = chRef1[(inData[num5 + 1] & 15) << 2];
    outChars[num3 + 3] = chRef1[0x40];
    num3 += 4;
    goto Label_0220;

    default:
    goto Label_0220;
 }
 outChars[num3] = chRef1[(inData[num5] & 0xfc) >> 2];
 outChars[num3 + 1] = chRef1[(inData[num5] & 3) << 4];
 outChars[num3 + 2] = chRef1[0x40];
 outChars[num3 + 3] = chRef1[0x40];
 num3 += 4;
     
Label_0220:;
      return num3;
}

int CBase64::ToBase64String(char* & pOut, char *pIn, int nLen)
{
 int nOut = CalculateOutputLength(nLen);
 pOut = new char[nOut + 1];
 int n = ConvertToBase64(pOut,pIn,nLen);
 pOut[n] = '/0';
 return n;
}
int CBase64::FromBase64String(char * & pOut,char * pIn)
{
 int temp = 0;
    int length2, length3;
    int blockCount;
    int paddingCount;
    int length = strlen(pIn);

    //find how many padding are there
    for (int x = 0; x < 2; x++)
    {
        if (pIn[length - x - 1] == '=')
            temp++;
    }
    paddingCount = temp;
    blockCount = length / 4;
    length2 = blockCount * 3;

    char * buffer = new char[length];//first conversion result
    char * buffer2 = new char[length2];//decoded array with padding
    for ( x = 0; x < length; x++)
    {
        buffer[x] = char2sixbit(pIn[x]);
    }

    char b, b1, b2, b3;
    char temp1, temp2, temp3, temp4;

    for (x = 0; x < blockCount; x++)
    {
        temp1 = buffer[x * 4];
        temp2 = buffer[x * 4 + 1];
        temp3 = buffer[x * 4 + 2];
        temp4 = buffer[x * 4 + 3];

        b = (char)(temp1 << 2);
        b1 = (char)((temp2 & 48) >> 4);
        b1 += b;

        b = (char)((temp2 & 15) << 4);
        b2 = (char)((temp3 & 60) >> 2);
        b2 += b;

        b = (char)((temp3 & 3) << 6);
        b3 = temp4;
        b3 += b;

        buffer2[x * 3] = b1;
        buffer2[x * 3 + 1] = b2;
        buffer2[x * 3 + 2] = b3;
    }
    //remove paddings
    length3 = length2 - paddingCount;
    pOut = new char[length3];

    for (x = 0; x < length3; x++)
    {
        pOut[x] = buffer2[x];
    }
 delete[] buffer;
 delete[] buffer2;
    return length3;
}

char CBase64::char2sixbit(char c)
{
 
    if (c == '=')
        return 0;
    else
    {
        for (int x = 0; x < 64; x++)
        {
            if (base64Table[x] == c)
                return x;
        }
        //should not reach here
        return 0;
    }
}

怎麼樣？還算精煉吧。