Base64算法
由于项目用到了字节数组与文本互相转换，所以自己写了一对方法用来把字节数组转成可见字符串，及把字符串转成字节数组的BASE64算法。
使用toBase64String的时候默认的是加上了回车换行的处理，但是在fromBase64String的时候无论有没有回车换行符都可以正确的转换。
这里的算法完全是自己由Base64思想自己做出来的，如果错误敬请指正。
使用的示例：
BYTE* bts(NULL); int len; LPCTSTR str=_T("abcdefg123456"); bts=this->fromBase64String(str, len);//转成字节数组 CString t = this->toBase64String(bts, len);//由字节数组再转回字符串 delete bts;
CString CTAXGDlg::toBase64String(BYTE* btyArray, int length) { CString strResult; if (length==0) { return strResult; } TCHAR base64[65]={ _T('A'), _T('B'), _T('C'), _T('D'), _T('E'), _T('F'), _T('G'), _T('H'), _T('I'), _T('J'), _T('K'), _T('L'), _T('M'), _T('N'), _T('O'), _T('P'), _T('Q'), _T('R'), _T('S'), _T('T'), _T('U'), _T('V'), _T('W'), _T('X'), _T('Y'), _T('Z'), _T('a'), _T('b'), _T('c'), _T('d'), _T('e'), _T('f'), _T('g'), _T('h'), _T('i'), _T('j'), _T('k'), _T('l'), _T('m'), _T('n'), _T('o'), _T('p'), _T('q'), _T('r'), _T('s'), _T('t'), _T('u'), _T('v'), _T('w'), _T('x'), _T('y'), _T('z'), _T('0'), _T('1'), _T('2'), _T('3'), _T('4'), _T('5'), _T('6'), _T('7'), _T('8'), _T('9'), _T('+'), _T('/'), _T('=') }; int nRemainder = length % 3;//num为剩余的字节数 int nlength = (length / 3) * 4; if (nRemainder!=0) { nlength += 4; } int lines = nlength / 0x50; nlength+=lines * 2;//×2是因为有两个回车换行符 TCHAR* chrArray=new TCHAR[nlength]; ::ZeroMemory(chrArray, nlength*sizeof(TCHAR)); int charIndex(0); int nLineChars(0); int nSourceIndex(0); for (nSourceIndex = 0; nSourceIndex < length - nRemainder; nSourceIndex += 3) { //每三个字节转成四个字节且，这四个字节值都不大于６４，这就保证了只会出现６４个字符中的一个。 chrArray[charIndex++] = base64[(btyArray[nSourceIndex] & 0xfc) >> 2]; chrArray[charIndex++] = base64[((btyArray[nSourceIndex] & 0x3) << 4) | ((btyArray[nSourceIndex + 1] & 0xF0) >> 4)]; chrArray[charIndex++] = base64[((btyArray[nSourceIndex + 1] & 0xF) << 2) | ((btyArray[nSourceIndex + 2] & 0xc0) >> 6)]; chrArray[charIndex++] = base64[btyArray[nSourceIndex + 2] & 0x3f]; nLineChars += 4; if (nLineChars == 0x50) { chrArray[charIndex++] = _T('/r'); chrArray[charIndex++] = _T('/n'); nLineChars = 0; } } //处理剩余的字节，如果剩余字节数不为０且没有添加换行符则添加换行符。 if (((nRemainder != 0)) && (nLineChars == 0x50)) { chrArray[charIndex++] = _T('/r'); chrArray[charIndex++] = _T('/n'); } switch (nRemainder) { case 1: chrArray[charIndex++] = base64[(btyArray[nSourceIndex] & 0xfc) >> 2]; chrArray[charIndex++] = base64[(btyArray[nSourceIndex] & 0x3) << 4]; chrArray[charIndex++] = base64[0x40]; chrArray[charIndex++] = base64[0x40]; break; case 2: chrArray[charIndex++] = base64[(btyArray[nSourceIndex] & 0xfc) >> 2]; chrArray[charIndex++] = base64[((btyArray[nSourceIndex] & 3) << 4) | ((btyArray[nSourceIndex + 1] & 240) >> 4)]; chrArray[charIndex++] = base64[(btyArray[nSourceIndex + 1] & 15) << 2]; chrArray[charIndex++] = base64[0x40]; break; } strResult=CString(chrArray, charIndex); delete[] chrArray; return strResult; } BYTE* CTAXGDlg::fromBase64String(LPCTSTR text, int& length) { //去掉回车换行符 int textLength(0); const TCHAR* pText=text; while(*pText++) { textLength++; } TCHAR* chrArray=new TCHAR[textLength+1]; ZeroMemory(chrArray, sizeof(TCHAR)*(textLength+1)); int nCount=0; for(int charIndex=0;charIndex<textLength;charIndex++) { TCHAR tmpChar=text[charIndex]; if (tmpChar==_T('/r') || tmpChar==_T('/n')) { continue; } if (tmpChar==_T('=')) { break; } chrArray[nCount++]=tmpChar; } int nRemainder=nCount%4; int tmpLength = (nCount/4) * 3; if(nRemainder!=0) { tmpLength+=3; } BYTE* btyArray=new BYTE[tmpLength]; int byteIndex(0); int nSourceIndex(0); for (nSourceIndex = 0; nSourceIndex < nCount-nRemainder; nSourceIndex++) { //每四个字符转成三个字节，这四个字符值都不大于６４。 TCHAR c1=chrArray[nSourceIndex++]; TCHAR c2=chrArray[nSourceIndex++]; TCHAR c3=chrArray[nSourceIndex++]; TCHAR c4=chrArray[nSourceIndex]; BYTE b1=getBase64Byte(c1); BYTE b2=getBase64Byte(c2); BYTE b3=getBase64Byte(c3); BYTE b4=getBase64Byte(c4); btyArray[byteIndex++] = (BYTE)(((b1 & 0x3f) << 2)|((b2 & 0xf0) >> 4)); btyArray[byteIndex++] = (BYTE)(((b2 & 0xf) << 4)|((b3 & 0xfc) >> 2)); btyArray[byteIndex++] = (BYTE)(((b3 & 0x3) << 6)|(b4 & 0x3f)); } switch(nRemainder) { case 3: { TCHAR c1=chrArray[nSourceIndex++]; TCHAR c2=chrArray[nSourceIndex++]; TCHAR c3=chrArray[nSourceIndex]; BYTE b1=getBase64Byte(c1); BYTE b2=getBase64Byte(c2); BYTE b3=getBase64Byte(c3); BYTE v1=(BYTE)(((b1 & 0x3f) << 2)|((b2 & 0xf0) >> 4)); BYTE v2=(BYTE)(((b2 & 0xf) << 4)|((b3 & 0xfc) >> 2)); btyArray[byteIndex++] = v1; btyArray[byteIndex++] = v2; } break; case 2: { TCHAR c1=chrArray[nSourceIndex++]; TCHAR c2=chrArray[nSourceIndex]; BYTE b1=getBase64Byte(c1); BYTE b2=getBase64Byte(c2); BYTE v1=(BYTE)(((b1 & 0x3f) << 2)|((b2 & 0xf0) >> 4)); btyArray[byteIndex++] = v1; } break; } delete[] chrArray; length=byteIndex; return btyArray; } BYTE CTAXGDlg::getBase64Byte(TCHAR value) { BYTE b(64); if (value>=_T('A') && value<=_T('Z')) { b=(BYTE)(value-_T('A')); } else if (value>=_T('a') && value<=_T('z')) { b=(BYTE)(value-_T('a')+26); } else if (value>=_T('0') && value<=_T('9')) { b=(BYTE)(value-_T('0')+52); } else if (value==_T('+')||value==_T('*')||value==_T('[')) { b=(BYTE)62; } else if (value==_T('/')||value==_T('-')||value==_T(']')) { b=(BYTE)63; } return b; }