XmlConvert.VerifyWhitespace Method (String)


The .NET API Reference documentation has a new home. Visit the .NET API Browser on docs.microsoft.com to see the new experience.

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

Namespace:   System.Xml
Assembly:  System.Xml (in System.Xml.dll)

public static string VerifyWhitespace(
	string content


Type: System.String

String to verify.

Return Value

Type: System.String

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

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.

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 = '_';

    // Write the root element.

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

    // Write the end tag for the legal element.
    // Write the end tag for the root element.

catch (Exception e)

Universal Windows Platform
Available since 8
.NET Framework
Available since 4.0
Portable Class Library
Supported in: portable .NET platforms
Available since 3.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
Return to top