base64编码

资料出处：http://my.csdn.net/cclongying1989/code/detail/13009

/* * *Base64? * * **/ #include "Base64.h" static const char *g_pCodes =    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="; static const unsigned char g_pMap[256] ={    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,    255, 255, 255, 255, 255, 255, 255,  62, 255, 255, 255,  63,     52,  53,  54,  55,  56,  57,  58,  59,  60,  61, 255, 255,    255, 254, 255, 255, 255,   0,   1,   2,   3,   4,   5,   6,      7,   8,   9,  10,  11,  12,  13,  14,  15,  16,  17,  18,     19,  20,  21,  22,  23,  24,  25, 255, 255, 255, 255, 255,    255,  26,  27,  28,  29,  30,  31,  32,  33,  34,  35,  36,     37,  38,  39,  40,  41,  42,  43,  44,  45,  46,  47,  48,     49,  50,  51, 255, 255, 255, 255, 255, 255, 255, 255, 255,    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,    255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,    255, 255, 255, 255}; CBase64::CBase64(){} CBase64::~CBase64(){} bool CBase64::Encode(const unsigned char *pIn, unsigned long uInLen, unsigned char *pOut, unsigned long *uOutLen){    unsigned long i, len2, leven;    unsigned char *p;     if(pOut == NULL || *uOutLen == 0)        return false;     //ASSERT((pIn != NULL) && (uInLen != 0) && (pOut != NULL) && (uOutLen != NULL));     len2 = ((uInLen + 2) / 3) << 2;    if((*uOutLen) < (len2 + 1)) return false;     p = pOut;    leven = 3 * (uInLen / 3);    for(i = 0; i < leven; i += 3)    {        *p++ = g_pCodes[pIn[0] >> 2];        *p++ = g_pCodes[((pIn[0] & 3) << 4) + (pIn[1] >> 4)];        *p++ = g_pCodes[((pIn[1] & 0xf) << 2) + (pIn[2] >> 6)];        *p++ = g_pCodes[pIn[2] & 0x3f];        pIn += 3;    }     if (i < uInLen)    {        unsigned char a = pIn[0];        unsigned char b = ((i + 1) < uInLen) ? pIn[1] : 0;        unsigned char c = 0;         *p++ = g_pCodes[a >> 2];        *p++ = g_pCodes[((a & 3) << 4) + (b >> 4)];        *p++ = ((i + 1) < uInLen) ? g_pCodes[((b & 0xf) << 2) + (c >> 6)] : '=';        *p++ = '=';    }     *p = 0; // Append NULL byte    *uOutLen = p - pOut;    return true;} bool CBase64::Encode(const unsigned char *pIn, unsigned long uInLen, string& strOut) {    unsigned long i, len2, leven;    strOut = "";     //ASSERT((pIn != NULL) && (uInLen != 0) && (pOut != NULL) && (uOutLen != NULL));     len2 = ((uInLen + 2) / 3) << 2;    //if((*uOutLen) < (len2 + 1)) return false;     //p = pOut;    leven = 3 * (uInLen / 3);    for(i = 0; i < leven; i += 3)    {        strOut += g_pCodes[pIn[0] >> 2];        strOut += g_pCodes[((pIn[0] & 3) << 4) + (pIn[1] >> 4)];        strOut += g_pCodes[((pIn[1] & 0xf) << 2) + (pIn[2] >> 6)];        strOut += g_pCodes[pIn[2] & 0x3f];        pIn += 3;    }     if (i < uInLen)    {        unsigned char a = pIn[0];        unsigned char b = ((i + 1) < uInLen) ? pIn[1] : 0;        unsigned char c = 0;         strOut += g_pCodes[a >> 2];        strOut += g_pCodes[((a & 3) << 4) + (b >> 4)];        strOut += ((i + 1) < uInLen) ? g_pCodes[((b & 0xf) << 2) + (c >> 6)] : '=';        strOut += '=';    }     //*p = 0; // Append NULL byte    //*uOutLen = p - pOut;    return true;} bool CBase64::Decode(const string& strIn, unsigned char *pOut, unsigned long *uOutLen) {    unsigned long t, x, y, z;    unsigned char c;    unsigned long g = 3;     //ASSERT((pIn != NULL) && (uInLen != 0) && (pOut != NULL) && (uOutLen != NULL));     for(x = y = z = t = 0; x < strIn.length(); x++)    {        c = g_pMap[strIn[x]];        if(c == 255) continue;        if(c == 254) { c = 0; g--; }         t = (t << 6) | c;         if(++y == 4)        {            if((z + g) > *uOutLen) { return false; } // Buffer overflow            pOut[z++] = (unsigned char)((t>>16)&255);            if(g > 1) pOut[z++] = (unsigned char)((t>>8)&255);            if(g > 2) pOut[z++] = (unsigned char)(t&255);            y = t = 0;        }    }     *uOutLen = z;    return true;}