Velutis Velutis - 1 year ago 185
C++ Question

How to read file which contains \uxxxx in vc++

I have txt file whose contents are:


How can I read such file to get result like this:


If I type this:

string str = _T("\u041f\u0435\u0440\u0432\u044b\u0439_\u0438\u043d\u0442\u0435\u0440\u0430\u043a\u0442\u0438\u0432\u043d\u044b\u0439_\u0438\u043d\u0442\u0435\u0440\u043d\u0435\u0442_\u043a\u0430\u043d\u0430\u043b");

then result in
is good but if I read it from file then it is the same like in file. I guess it is because '\u' becomes '\u'.
Is there simple way to convert \uxxxx notation to corresponding symbols in C++?

Answer Source

Here is an example for MSalters's suggestion:

#include <iostream>
#include <string>
#include <fstream>
#include <algorithm>
#include <sstream>
#include <iomanip>
#include <locale>

#include <boost/scoped_array.hpp>
#include <boost/regex.hpp>
#include <boost/numeric/conversion/cast.hpp>

std::wstring convert_unicode_escape_sequences(const std::string& source) {
  const boost::regex regex("\\\\u([0-9A-Fa-f]{4})");  // NB: no support for non-BMP characters
  boost::scoped_array<wchar_t> buffer(new wchar_t[source.size()]);
  wchar_t* const output_begin = buffer.get();
  wchar_t* output_iter = output_begin;
  std::string::const_iterator last_match = source.begin();
  for (boost::sregex_iterator input_iter(source.begin(), source.end(), regex), input_end; input_iter != input_end; ++input_iter) {
    const boost::smatch& match = *input_iter;
    output_iter = std::copy(match.prefix().first, match.prefix().second, output_iter);
    std::stringstream stream;
    stream << std::hex << match[1].str() << std::ends;
    unsigned int value;
    stream >> value;
    *output_iter++ = boost::numeric_cast<wchar_t>(value);
    last_match = match[0].second;
  output_iter = std::copy(last_match, source.end(), output_iter);
  return std::wstring(output_begin, output_iter);

int wmain() {
  const std::wstring filename = L"test.txt";
  std::ifstream stream(filename.c_str(), std::ios::in | std::ios::binary);
  stream.seekg(0, std::ios::end);
  const std::ifstream::streampos size = stream.tellg();
  boost::scoped_array<char> buffer(new char[size]);, size);
  const std::string source(buffer.get(), size);
  const std::wstring result = convert_unicode_escape_sequences(source);
  std::wcout << result << std::endl;

I'm always surprised how complicated seemingly simple things like this are in C++.

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