Detect Unicode Character in string

Question

I have string input. I want to check all the characters and prompt the user if there is any Unicode character in input string.

How can I do this validation in C++.

eg. In Notepad if you enter any Unicode character and try to save it with ANSI Encoding, it will prompt about Unicode character. I want to do similar validation.

Answer 1

You can use IsTextUnicode function. That's the function notepad uses as far as I know.

MSDN-Link: http://msdn.microsoft.com/en-us/library/windows/desktop/dd318672%28v=vs.85%29.aspx

Just insert NULL as the last parameter.

#include <string>
#include <Windows.h>

int main()
{
  std::string s = "Hallo!";
  std::wstring ws = L"Hello!";

  if (::IsTextUnicode(ws.c_str(), ws.length(), NULL) == 1)
  {
    // is unicode
    int i = 0;
  }
  else
  {
    // no unicode
    int i = 1;
  }

  return 0;
}

Answer 2

What Notepad warns you about is slightly different: It warns you about Unicode characters that cannot be converted to the desired code page. IOW, WideCharToMultiByte(CP_ACP, ..., &lpUsedDefaultChar) causes lpUsedDefaultChar to be set to TRUE.

Substitute CP_ACP for the encoding you want, except CP_UTF8 which makes no sense. UTF8 supports all Unicode characters.