Base64编码的连接code。使用升压抛出异常 [英] Base64 encode using boost throw exception

问题描述

我试图用升压的base64 EN codeR，我发现了一个例子，但我得到了和异常

I trying to use boost base64 encoder, I found an example but I got and exception

typedef 
transform_width< binary_from_base64<std::string::const_iterator>, 8, 6 > it_binary_t

这是我用

std::string b64E(it_binary_t(Encrip.begin()), it_binary_t(Encrip.end()));

我知道了。

在agentid_ coder.exe 0x75b1b9bc未处理的异常：微软C ++
  例外：提高::档案::迭代器:: dataflow_exception在内存
  位置0x0046ed94 ..

Unhandled exception at 0x75b1b9bc in agentid_coder.exe: Microsoft C++ exception: boost::archive::iterators::dataflow_exception at memory location 0x0046ed94..

我发现这个解决办法，但我得到了同样的结果。

I found this workaround but I get the same result

 string dec( 
        it_binary_t(Encrip.begin()), 
        it_binary_t(Encrip.begin() + Encrip.length() - 1) 
        ); 

我使用MSVS2008并提高1.38

I am using MSVS2008 and boost 1.38

推荐答案

不幸的是，组合两 iterator_adaptors binary_from_base64 和 transform_width 不是一个完整的base64连接codeR /德$ C $铬。 Base64编码重新presents的24位（3个字节）为4个字符，每一个连接$ C $ 6 CS位。如果输入数据不是这样的3字节组的整数倍它有一个或两个零字节填充。为了表明填充字节是多少增加，一个或两个 = 字符被追加到EN codeD字符串。

Unfortunately the combination of the two iterator_adaptors binary_from_base64 and transform_width is not a complete base64 encoder/decoder. Base64 represents groups of 24 bits (3 bytes) as 4 characters, each of which encodes 6 bits. If the input data is not an integer multiple of such 3 byte groups it has to be padded with one or two zero bytes. To indicate how many padding bytes were added, one or two = characters are appended to the encoded string.

transform_width ，这是负责的8位二进制整数6bit的转换不会自动应用此填充，它也可以由用户来完成。一个简单的例子：

transform_width, which is responsible for the 8bit binary to 6bit integer conversion does not apply this padding automatically, it has do be done by the user. A simple example:

#include <boost/archive/iterators/base64_from_binary.hpp>
#include <boost/archive/iterators/binary_from_base64.hpp>
#include <boost/archive/iterators/transform_width.hpp>
#include <boost/archive/iterators/insert_linebreaks.hpp>
#include <boost/archive/iterators/remove_whitespace.hpp>
#include <iostream>
#include <string>

using namespace boost::archive::iterators;
using namespace std;

int main(int argc, char **argv) {
  typedef transform_width< binary_from_base64<remove_whitespace<string::const_iterator> >, 8, 6 > it_binary_t;
  typedef insert_linebreaks<base64_from_binary<transform_width<string::const_iterator,6,8> >, 72 > it_base64_t;
  string s;
  getline(cin, s, '\n');
  cout << "Your string is: '"<<s<<"'"<<endl;

  // Encode
  unsigned int writePaddChars = (3-s.length()%3)%3;
  string base64(it_base64_t(s.begin()),it_base64_t(s.end()));
  base64.append(writePaddChars,'=');

  cout << "Base64 representation: " << base64 << endl;

  // Decode
  unsigned int paddChars = count(base64.begin(), base64.end(), '=');
  std::replace(base64.begin(),base64.end(),'=','A'); // replace '=' by base64 encoding of '\0'
  string result(it_binary_t(base64.begin()), it_binary_t(base64.end())); // decode
  result.erase(result.end()-paddChars,result.end());  // erase padding '\0' characters
  cout << "Decoded: " << result << endl;
  return 0;
}

请注意，我添加了 insert_linebreaks 和 remove_whitespace 迭代器，这样就很好地格式化和base64输入流中的Base64输出换行可德codeD。这些都是可选的，但。

Note that I added the insert_linebreaks and remove_whitespace iterators, so that the base64 output is nicely formatted and base64 input with line breaks can be decoded. These are optional though.

与要求不同的填充不同的输入字符串运行：

Run with different input strings which require different padding:

$ ./base64example
Hello World!
Your string is: 'Hello World!'
Base64 representation: SGVsbG8gV29ybGQh
Decoded: Hello World!
$ ./base64example
Hello World!!
Your string is: 'Hello World!!'
Base64 representation: SGVsbG8gV29ybGQhIQ==
Decoded: Hello World!!
$ ./base64example
Hello World!!!
Your string is: 'Hello World!!!'
Base64 representation: SGVsbG8gV29ybGQhISE=
Decoded: Hello World!!!

您可以检查这个在线连接$ c中的字符串的base64 $ CR /德codeR 。

这篇关于Base64编码的连接code。使用升压抛出异常的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！