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__NO POINTS__<br />
<br />
... provided you don't turn on the multi-line modifier.
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__NO POINTS__

... provided you don't turn on the multi-line modifier.

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@DTwined: Because you are using a single line string the above code will work. Depending on your programming language though, there are probably better ways to do this with trimming and checking for zero length. Some languages provide helper methods like <i>string.IsNullOrEmpty</i> and <i>string.IsNullOrWhiteSpace</i> in .NET.<br />
<br />
@kaufmed: If the string was multi-line then it actually contains characters (carriage returns and/or line feeds). The above regular expression means it genuinely empty.
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@DTwined: Because you are using a single line string the above code will work. Depending on your programming language though, there are probably better ways to do this with trimming and checking for zero length. Some languages provide helper methods like string.IsNullOrEmpty and string.IsNullOrWhiteSpace in .NET.

@kaufmed: If the string was multi-line then it actually contains characters (carriage returns and/or line feeds). The above regular expression means it genuinely empty.

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<blockquote>
If the string was multi-line then it actually contains characters
</blockquote>
I didn't say the string would be multi-line; I said the multi-line modifier is turned on, which changes the meaning of ^ and $. However, when I tested it didn't seem to make a difference, so my comment above may be moot anyway &nbsp;= )
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> If the string was multi-line then it actually contains characters

I didn't say the string would be multi-line; I said the multi-line modifier is turned on, which changes the meaning of ^ and $. However, when I tested it didn't seem to make a difference, so my comment above may be moot anyway  = )

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Hello -<br />
<br />
I need a regular expression that will tell me if the string I am looking at is empty.<br />
<br />
Thanks,<br />
DT
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Hello -

I need a regular expression that will tell me if the string I am looking at is empty.

Thanks,
DT

regular expression match empty string

A regular expression ("regex") is a sequence of characters that define a search pattern, mainly for use in pattern matching with strings, or string matching, i.e. "find and replace"-like operations. Regular expression processors are found in several search engines, search and replace dialogs of several word processors and text editors, and in the command lines of text processing utilities, such as sed and AWK. Many programming languages provide regular expression capabilities, some built-in, for example Perl, JavaScript, Ruby, AWK, and Tcl, and others via a standard library, for example .NET languages, Java, Python and C++ (since C++11). Most other languages offer regular expressions via a library.