Base64Encode编码函数

来源：互联网发布：魅族抢购软件神器编辑：程序博客网时间：2024/05/16 16:21

char* Base64Encode(const char *str,int length)

{

static   char   base64_table[]   =
{   'A',   'B',   'C',   'D',   'E',   'F',   'G',   'H',   'I',   'J',   'K',   'L',   'M',
'N',   'O',   'P',   'Q',   'R',   'S',   'T',   'U',   'V',   'W',   'X',   'Y',   'Z',
'a',   'b',   'c',   'd',   'e',   'f',   'g',   'h',   'i',   'j',   'k',   'l',   'm',
'n',   'o',   'p',   'q',   'r',   's',   't',   'u',   'v',   'w',   'x',   'y',   'z',
'0',   '1',   '2',   '3',   '4',   '5',   '6',   '7',   '8',   '9',   '+',   '/',   '/0'
};

static char base64_pad = '=';
const char *current = (   const   char*)str;
int i = 0;
char *result = (   char *)malloc(((length + 3 - length % 3) * 4 / 3 + 1) * sizeof(char));
while (length > 2) {
  /*   keep   going   until   we   have   less   than   24   bits   */
  result[i++] = base64_table[current[0] >> 2];
  result[i++] = base64_table[((current[0] & 0x03) << 4) + (current[1] >> 4)];
  result[i++] = base64_table[((current[1] & 0x0f) << 2) + (current[2] >> 6)];
  result[i++] = base64_table[current[2] & 0x3f];
  current += 3;
  length -= 3;   /*   we   just   handle   3   octets   of   data   */
}
/*   now   deal   with   the   tail   end   of   things   */
if   (length != 0)
{
  result[i++] = base64_table[current[0] >> 2];
  if   (length > 1)
  {
   result[i++] = base64_table[((current[0] & 0x03 ) << 4) + (current[1] >> 4)];
   result[i++] = base64_table[(current[1] & 0x0f) << 2];
   result[i++] = base64_pad;
  }
  else
  {
   result[i++] = base64_table[(current[0] & 0x03) << 4];
   result[i++] = base64_pad;
   result[i++] = base64_pad;
  }
}
result[i] = '/0';   //   printf("%s/n",result);
return result;
}