Re: Get ASCII value for character when higher than 127

MrAsm <>
Tue, 29 May 2007 14:41:39 GMT
On 29 May 2007 07:01:32 -0700, wrote:

Hi Sandra,

But, again, this works fine for normal characters, but not for the
special ones. This whole encoding stuff is starting to driving me

In this message you can find a function I wrote in C++ to convert
"Windows Unicode" strings (i.e. UTF-16 Unicode) to the UTF-8 Unicode.

The function prototype is:

  std::string StringUnicodeToUTF8( const wchar_t * unicodeString )

it gets a Unicode (UTF-16) string as input, and returns a UTF-8
encoded string as output.

 - The function may throw exceptions on errors.
 - The "core" of this function is the ::WideCharToMultiByte Win32 API

You could use this function to convert your (Unicode) strings into
UTF-8, and write them into XML files.

<CODE language="C++">

    // Your Unicode strings
    // (e.g. read from edit controls or whatever...)
    const wchar_t * UserName = L"MisterJohn_?";
    const wchar_t * Password = L"???";
    // I put some typical Italian characters (vowels with stress)
    // inside the strings.
    // I don't know if the newsgroup will show them correctly;
    // you may try with your own characters and also Chinese
    // characters, etc.

    // The XML file header with UTF-8 encoding
    const std::string xmlHeader =
        "<?xml version=\"1.0\" encoding=\"UTF-8\"?>";

    // Build the XML text into an output string stream
    std::ostringstream xmlString;
    xmlString << xmlHeader << std::endl;

    xmlString << "<userdata>";
    xmlString << "<username>" << StringUnicodeToUTF8( UserName )
              << "</username>" << std::endl;

    xmlString << "<password>" << StringUnicodeToUTF8( Password )
              << "</password>" << std::endl;

    xmlString << "</userdata>" << std::endl;

    // Write content to "user.xml" file
    std::ofstream xmlFile( "user.xml" );
    xmlFile << xmlString.str();


You can read the XML file from C# using code like the following (it
reads username and password from the XML file):

<CODE language="C#">
    // Clear user name and password
    // (txtUserName and txtPassword are TextBox'es)
    txtUserName.Text = "";
    txtPassword.Text = "";

    // Read data from XML file
    XmlTextReader reader = new XmlTextReader( @"user.xml" );
    while (reader.Read())
        if ( (reader.NodeType == XmlNodeType.Element))
            if (reader.LocalName.Equals("username"))
                txtUserName.Text = reader.ReadString();
            else if (reader.LocalName.Equals("password"))
                txtPassword.Text = reader.ReadString();

If you want to "scramble" the input XML file on the C++ side using
XOR, you could do as follows:

<CODE language="C++">
    // Crypt file using XOR

    // xmlString is an std::ostringstream,
    // containing the text of the XML file.
    std::string originalFile = xmlString.str();

    // Destination file
    std::ofstream scrambledFile( "user.xml.crypt" );

    // Key for XOR crypt
    const char scrambleKey = 0x77;

    // Scrambling loop
    for ( std::string::const_iterator it = originalFile.begin();
          it != originalFile.end(); ++it )
        scrambledFile.put( (*it) ^ scrambleKey );

And to read it back and un-sramble from C#, you could use code like
this (consider that I'm not a C# expert, so maybe there could exist a
better C# code than what I developed here):

<CODE language="C#">
    // Decrypt file

    // Input file to un-scramble
    FileStream inputFile = new FileStream(@"user.xml.crypt",
    BinaryReader inputReader = new BinaryReader(inputFile);

    // Output file
    FileStream outputFile = new FileStream(@"user.xml",
    BinaryWriter outputWriter = new BinaryWriter(outputFile);

    // XOR key
    const byte scrambleKey = 0x77;

    // Un-scrambling loop
    for (long i = 0; i < inputReader.BaseStream.Length; i++)
        byte dataByte = inputReader.ReadByte();
        dataByte ^= scrambleKey;

    // Close files



And there is the main StringUnicodeToUTF8 function:

<CODE language="C++">

// Convert (encode) a Unicode UTF-16 string to Unicode UTF-8.
// by MrAsm
std::string StringUnicodeToUTF8( const wchar_t * unicodeString )
    // Check input string pointer
    if ( unicodeString == NULL )
        throw std::invalid_argument(
            "StringUnicodeToUTF8: Bad pointer" );

    // Special case of empty string
    if ( *unicodeString == L'\0' )
        return "";

    // One Unicode UTF-16 character may be converted
    // up to four (4) UTF-8 characters.
    const int lengthW = ::lstrlenW( unicodeString ) + 1;
    const int lengthUtf8 = lengthW * 4;

    // Buffer for UTF-8 string
    std::vector< char > utf8Buffer;
    utf8Buffer.resize( lengthUtf8 );

    // Try converting from Unicode UTF-16 to UTF-8
    if ( ::WideCharToMultiByte(
            CP_UTF8, // Convert to UTF-8
            0, // Default flags [not used]
            unicodeString, // Pointer to Unicode string to be
                            // converted
            lengthW, // Number of wide-chars in input string
                            // (including NUL terminator)
            &utf8Buffer[0], // Pointer to buffer to receive the
                            // destination string
            lengthUtf8, // Size, in bytes, of the destination
                            // buffer
            NULL, // [default - not used]
            NULL ) // [default - not used]
            == 0 )
        throw std::runtime_error(
            "StringUnicodeToUTF8: Conversion failed." );

    // Return the UTF-8 string
    return std::string( &utf8Buffer[0] );



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