Programmer

Misha

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The technique used in my pattern is a "negative lookbehind" before the qwe and a "negative lookahead" after it.
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Thank you very mach! <br />
But can you explain me, how does work &nbsp;&quot;?&lt;!&quot; &nbsp; &nbsp; &nbsp; and &nbsp; &quot;?!&quot; &nbsp; ?
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(?&lt;!abc)def means don't match def if it has abc just before it. This is a negative lookbehind.<br>abc(?!def) means don't match abc if it has def just after it. This is a negative lookahead.
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Hello!<br />
<br />
I need find some substring in string. There are NOT letter symbols before and after this substring. Also there are begin and end of string near this substring.<br />
<br />
For example, I need find &quot;qwe&quot; in &nbsp;next cases:<br />
1) &quot;&nbsp;qwe &quot;<br />
2) &quot;+qwe(&quot;<br />
3) &quot;&nbsp;qwe&quot;<br />
4) &quot;qwe(&quot;<br />
5) &quot;qwe&quot;<br />
<br />
And NOT find &quot;qwe&quot; in case &quot;qwer&quot;<br />
I try this regex:<br />
<br />

<pre><code class="code-1 nolinks" id="code-10-29180398-1"><span>[^a-zA-Z](qwe)[^a-zA-Z]</span>
</code></pre>
<br />
This regex can not find &quot;qwe&quot; in 3,4 and 5 case .<br />
How add symbols begin and end of string in [ ???]
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Hello!

I need find some substring in string. There are NOT letter symbols before and after this substring. Also there are begin and end of string near this substring.

For example, I need find "qwe" in  next cases:
1) " qwe "
2) "+qwe("
3) " qwe"
4) "qwe("
5) "qwe"

And NOT find "qwe" in case "qwer"
I try this regex:

(CODE)

This regex can not find "qwe" in 3,4 and 5 case .
How add symbols begin and end of string in [ ???]

C# Regex

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.

Regular Expressions

C# is an object-oriented programming language created in conjunction with Microsoft’s .NET framework. Compilation is usually done into the Microsoft Intermediate Language (MSIL), which is then JIT-compiled to native code (and cached) during execution in the Common Language Runtime (CLR).