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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><!-- Copyright 1997 The Open Group, All Rights Reserved --><title>regcmp</title></head><body bgcolor=white><center><font size=2>The Single UNIX ® Specification, Version 2<br>Copyright © 1997 The Open Group</font></center><hr size=2 noshade><h4><a name = "tag_000_008_006"> </a>NAME</h4><blockquote>regcmp, regex - compile and execute a regular expression(<b>LEGACY</b>)</blockquote><h4><a name = "tag_000_008_007"> </a>SYNOPSIS</h4><blockquote><pre><code>#include <<a href="libgen.h.html">libgen.h</a>>char *regcmp (const char *<i>string1</i> , ... /*, (char *)0 */);char *regex (const char *<i>re</i>, const char *<i>subject</i> , ... );extern char *__loc1;</code></pre></blockquote><h4><a name = "tag_000_008_008"> </a>DESCRIPTION</h4><blockquote>The<i>regcmp()</i>function compiles a regular expression consisting of the concatenatedarguments and returns a pointer to the compiled form.The end of arguments is indicated by a null pointer.The<i><a href="malloc.html">malloc()</a></i>function is used to create space for the compiled form. It is the process'responsibility to free unneeded space so allocated. A null pointer returnedfrom<i>regcmp()</i>indicates an invalid argument.<p>The<i><a href="regex.html">regex()</a></i>function executes a compiled pattern against the<i>subject</i>string. Additional arguments of type<b>char *</b>must be passed to receive matched subexpressions back. If an insufficientnumber of arguments is passed to accept all the values that the regularexpression returns, the behaviour is undefined. A global character pointer<b>__loc1</b>points to the first matched character in the<i>subject</i>string. Both<i>regcmp()</i>and<i><a href="regex.html">regex()</a></i>were largely borrowed from the editor,and are defined in<i><a href="re_comp.html">re_comp()</a></i>,but the syntax and semantics have been changed slightly.The following are the valid symbols and their associated meanings:<dl compact><dt>[]*.^<dd>These symbols retain their meaning as defined in<i><a href="re_comp.html">re_comp()</a></i>.<dt>$<dd>Matches the end of the string; \n matches a new-line.<dt>-<dd>Used within brackets, the hyphen signifies an ASCII character range.For example, [a-z] is equivalent to [abcd ... xyz] . The -can represent itself only if used as the first or last character.For example, the character class expression []-]matches the characters ] and -.<dt>+<dd>A regular expression followed by +means one or more times. For example, [0-9]+is equivalent to [0-9][0-9]* .<dt>{<i>m</i>} {<i>m</i>,} {<i>m</i>,<i>u</i>}<dd><br>Integer values enclosed in { } indicate the number of times the precedingregular expression can be applied. The value<i>m</i>is the minimum number and<i>u</i>is a number, less than 256, which is the maximum. If the value of either<i>m</i>or<i>u</i>is 256 or greater, the behaviour is undefined. The syntax <b>{</b>m<b>}</b>indicates the exact number of times the regular expression can be applied.The syntax <b>{</b>m<b>,}</b> is analogous to <b>{</b>m<b>,</b>infinity<b>}</b>.The plus (+) and asterisk (*) operations are equivalent to<b>{1,}</b>and<b>{0,}</b>respectively.<dt>( ... )$<i>n</i><dd>The value of the enclosed regular expression is returned.The value is stored in the<i> (n+1)</i>thargument following the<i>subject</i>argument. A maximum of ten enclosed regular expressions are allowed. The<i><a href="regex.html">regex()</a></i>function makes its assignments unconditionally.<dt>( ... )<dd>Parentheses are used for grouping. An operator, such as<b>*</b>,<b>+</b>,or<b>{ }</b>can work on a single character or a regular expression enclosed inparentheses. For example, (a*(cb+)*)$0 .</dl><p>Since all of the above defined symbols are special characters,they must be escaped to be used as themselves.<p>The behaviour of<i>regcmp()</i>and<i><a href="regex.html">regex()</a></i>in locales other than the POSIX locale is unspecified.<p>These interfaces need not be reentrant.</blockquote><h4><a name = "tag_000_008_009"> </a>RETURN VALUE</h4><blockquote>Upon successful completion,<i>regcmp()</i>returns a pointer to the compiled regular expression. Otherwise, anull pointer is returned and<i>errno</i>may be set to indicate the error.<p>Upon successful completion,<i><a href="regex.html">regex()</a></i>returns a pointer to the next unmatched character in the subject string.Otherwise, a null pointer is returned.<p>The<i><a href="regex.html">regex()</a></i>function returns a null pointer on failure, or a pointer to the next unmatchedcharacter on success.</blockquote><h4><a name = "tag_000_008_010"> </a>ERRORS</h4><blockquote>The<i>regcmp()</i>function may fail if:<dl compact><dt>[ENOMEM]<dd>Insufficient storage space was available.</dl><p>No errors are defined for<i><a href="regex.html">regex()</a></i>.</blockquote><h4><a name = "tag_000_008_011"> </a>EXAMPLES</h4><blockquote>None.</blockquote><h4><a name = "tag_000_008_012"> </a>APPLICATION USAGE</h4><blockquote>For portability to implementations conforming to earlier versions of thisspecification,<i><a href="regcomp.html">regcomp()</a></i>is preferred over this function.<p>User programs that use<i>regcmp()</i>may run out of memory if<i>regcmp()</i>is called iteratively without freeing compiled regular expression stringsthat are no longer required.</blockquote><h4><a name = "tag_000_008_013"> </a>FUTURE DIRECTIONS</h4><blockquote>None.</blockquote><h4><a name = "tag_000_008_014"> </a>SEE ALSO</h4><blockquote><i><a href="malloc.html">malloc()</a></i>,<i><a href="regcomp.html">regcomp()</a></i>,<i><a href="libgen.h.html"><libgen.h></a></i>.</blockquote><hr size=2 noshade><center><font size=2>UNIX ® is a registered Trademark of The Open Group.<br>Copyright © 1997 The Open Group<br> [ <a href="../index.html">Main Index</a> | <a href="../xshix.html">XSH</a> | <a href="../xcuix.html">XCU</a> | <a href="../xbdix.html">XBD</a> | <a href="../cursesix.html">XCURSES</a> | <a href="../xnsix.html">XNS</a> ]</font></center><hr size=2 noshade></body></html>⌨️ 快捷键说明
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