XmlConvert.VerifyWhitespace(String) Method

Definition

Namespace:

System.Xml

Assembly:

System.Xml.ReaderWriter.dll

Source:

XmlConvert.cs

Returns the passed-in string instance if all the characters in the string argument are valid whitespace characters.

public:
 static System::String ^ VerifyWhitespace(System::String ^ content);

public static string VerifyWhitespace (string content);

static member VerifyWhitespace : string -> string

Public Shared Function VerifyWhitespace (content As String) As String

Parameters

content

String

String to verify.

Returns

String

The passed-in string instance if all the characters in the string argument are valid whitespace characters, otherwise null.

Examples

The following example uses the VerifyWhitespace method to detect the presence of an invalid character in a value assigned to the start element.

XmlTextWriter writer5 = new XmlTextWriter("outFile.xml", null);
char illegalWhiteSpaceChar = '_';

try
{
    // Write the root element.
    writer5.WriteStartElement("root");

    writer5.WriteStartElement("legalElement");
    // Throw an exception due illegal white space character.
    writer5.WriteString("ValueText" +
        XmlConvert.VerifyWhitespace("\t" + illegalWhiteSpaceChar));

    // Write the end tag for the legal element.
    writer5.WriteEndElement();
    // Write the end tag for the root element.
    writer5.WriteEndElement();
    writer5.Close();
}
catch (Exception e)
{
    Console.WriteLine(e.Message);
    writer5.Close();
}

Dim writer5 As XmlTextWriter = New XmlTextWriter("outFile.xml", Nothing)
Dim illegalWhiteSpaceChar As Char = "_"

Try
    ' Write the root element.
    writer5.WriteStartElement("root")
    writer5.WriteStartElement("legalElement")
    ' Throw an exception due illegal white space character.
    writer5.WriteString("ValueText" + _
        XmlConvert.VerifyWhitespace("   " + illegalWhiteSpaceChar))

    writer5.WriteEndElement()

    ' Write the end tag for the root element.
    writer5.WriteEndElement()

    writer5.Close()

Catch e As XmlException
    Console.WriteLine(e.Message)
    writer5.Close()
End Try

Remarks

No other values than the passed in argument should be returned. The characters that are valid for whitespace do not vary between XML editions, so no xml version overload is required.

See XML 1.0 spec (fourth edition) production [3] S for details on the allowed characters.

If the parameter is null, an ArgumentNullException will be thrown.

If any of the characters are not valid whitespace characters, an XmlException is thrown with information about the first invalid character encountered.