Why Is string.IsNullOrWhiteSpace(“\0”) False in .NET?

.netc#-4.0string

I faced a problem where invisible character \0 which is pretty like a 'white space' not considered as white space by the string.IsNullOrWhiteSpace method. I wonder why this implemented in .NET in so manner and is there any alternative to string.IsNullOrWhiteSpace which can properly handle null-terminate character?
Thanks in advance.

Best Answer

U+0000 isn't whitespace, basically. char.IsWhitespace('\0') returns false, it's not listed as whitespace...

The null part of IsNullOrWhitespace refers to the string reference itself - not the contents, if that's what you were thinking of.

Note that strings in .NET aren't logically "null-terminated" within managed code, although in practice at the CLR level they are, for interop purposes. (The string knows its own length, but in order to make it easier to work with native code which does expect a null terminator, the CLR ensures that there's always a U+0000 after the content of the string.) If you end up with a string containing \0 you should probably fix whatever produced it to start with.

Related Solutions

C# – string.IsNullOrEmpty vs string.IsNullOrWhiteSpace

The best practice is selecting the most appropriate one.

.Net Framework 4.0 Beta 2 has a new IsNullOrWhiteSpace() method for strings which generalizes the IsNullOrEmpty() method to also include other white space besides empty string.

The term “white space” includes all characters that are not visible on screen. For example, space, line break, tab and empty string are white space characters*.

Reference : Here

For performance, IsNullOrWhiteSpace is not ideal but is good. The method calls will result in a small performance penalty. Further, the IsWhiteSpace method itself has some indirections that can be removed if you are not using Unicode data. As always, premature optimization may be evil, but it is also fun.

Reference : Here

Check the source code (Reference Source .NET Framework 4.6.2)

IsNullorEmpty

[Pure]
public static bool IsNullOrEmpty(String value) {
    return (value == null || value.Length == 0);
}

IsNullOrWhiteSpace

[Pure]
public static bool IsNullOrWhiteSpace(String value) {
    if (value == null) return true;

    for(int i = 0; i < value.Length; i++) {
        if(!Char.IsWhiteSpace(value[i])) return false;
    }

    return true;
}

Examples

string nullString = null;
string emptyString = "";
string whitespaceString = "    ";
string nonEmptyString = "abc123";

bool result;

result = String.IsNullOrEmpty(nullString);            // true
result = String.IsNullOrEmpty(emptyString);           // true
result = String.IsNullOrEmpty(whitespaceString);      // false
result = String.IsNullOrEmpty(nonEmptyString);        // false

result = String.IsNullOrWhiteSpace(nullString);       // true
result = String.IsNullOrWhiteSpace(emptyString);      // true
result = String.IsNullOrWhiteSpace(whitespaceString); // true
result = String.IsNullOrWhiteSpace(nonEmptyString);   // false

Best Answer

Related Solutions

C# – string.IsNullOrEmpty vs string.IsNullOrWhiteSpace

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