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Please note that @ozo's pattern will still match a substring of the string you're testing, so that values like te4.4 or tena will match. Depending on the circumstances, this may or may not matter.<br />
<br />
If you're validating a form field, it probably does matter, in which case you'll probably want something like:<br />

<pre><code id="code-20-42660852-1">^(na|NA|\d+(\.\d*)?)$</code></pre>
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Please note that @ozo's pattern will still match a substring of the string you're testing, so that values like te4.4 or tena will match. Depending on the circumstances, this may or may not matter.

If you're validating a form field, it probably does matter, in which case you'll probably want something like:


^(na|NA|\d+(\.\d*)?)$

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Please suggest me regular expression to allow all decimal number or text such as &quot;na&quot; OR &quot;NA&quot;<br />
like<br />
4.4 <b>correct</b><br />
0.5 <b>correct</b><br />
6 <b>correct</b><br />
te <b>WRONG</b><br />
na <b>correct</b><br />
NA <b>correct</b>
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Please suggest me regular expression to allow all decimal number or text such as "na" OR "NA"
like
4.4 correct
0.5 correct
6 correct
te WRONG
na correct
NA correct

Regular expression to allow decimal or text

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

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