C++进行base64编码和解码

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base64.cpp

#include "base64.h"#include <iostream>static const std::string base64_chars =              "ABCDEFGHIJKLMNOPQRSTUVWXYZ"             "abcdefghijklmnopqrstuvwxyz"             "0123456789+/";static inline bool is_base64(unsigned char c) {  return (isalnum(c) || (c == '+') || (c == '/'));}std::string base64_encode(unsigned char const* bytes_to_encode, unsigned int in_len) {  std::string ret;  int i = 0;  int j = 0;  unsigned char char_array_3[3];  unsigned char char_array_4[4];  while (in_len--) {    char_array_3[i++] = *(bytes_to_encode++);    if (i == 3) {      char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;      char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);      char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);      char_array_4[3] = char_array_3[2] & 0x3f;      for(i = 0; (i <4) ; i++)        ret += base64_chars[char_array_4[i]];      i = 0;    }  }  if (i)  {    for(j = i; j < 3; j++)      char_array_3[j] = '\0';    char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;    char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);    char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);    char_array_4[3] = char_array_3[2] & 0x3f;    for (j = 0; (j < i + 1); j++)      ret += base64_chars[char_array_4[j]];    while((i++ < 3))      ret += '=';  }  return ret;}std::string base64_decode(std::string const& encoded_string) {  int in_len = encoded_string.size();  int i = 0;  int j = 0;  int in_ = 0;  unsigned char char_array_4[4], char_array_3[3];  std::string ret;  while (in_len-- && ( encoded_string[in_] != '=') && is_base64(encoded_string[in_])) {    char_array_4[i++] = encoded_string[in_]; in_++;    if (i ==4) {      for (i = 0; i <4; i++)        char_array_4[i] = base64_chars.find(char_array_4[i]);      char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);      char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);      char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];      for (i = 0; (i < 3); i++)        ret += char_array_3[i];      i = 0;    }  }  if (i) {    for (j = i; j <4; j++)      char_array_4[j] = 0;    for (j = 0; j <4; j++)      char_array_4[j] = base64_chars.find(char_array_4[j]);    char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);    char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);    char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];    for (j = 0; (j < i - 1); j++) ret += char_array_3[j];  }  return ret;}

base64.h

#include <string>std::string base64_encode(unsigned char const* , unsigned int len);std::string base64_decode(std::string const& s);

测试文件

#include "base64.h"#include <iostream>int main() {  const std::string s = "ADP GmbH\nAnalyse Design & Programmierung\nGesellschaft mit beschränkter Haftung" ;  std::string encoded = base64_encode(reinterpret_cast<const unsigned char*>(s.c_str()), s.length());  std::string decoded = base64_decode(encoded);  std::cout << "encoded: " << encoded << std::endl;  std::cout << "decoded: " << decoded << std::endl;  return 0;}

http://blog.csdn.net/sky04/article/details/6881649