blocks|key|636467|text|你在正确的轨道上。您需要在regext中为特殊字符留空格。那个？是一个特殊字符，应该使用\？进行转义，并且点也应该使用斜杠进行转义。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|636468|最后，您不应该使用\b选项，它不适用于您的情况。|636469|尝试：|636470|if+(!preg_match('/(\.php\?){1}/',+$cfg_path))
{
++++$error+=+true;
++++echo+'<error+elementid="cfg_path"+message="PATH+-+make+sure+you+have+a+\'.php?\'+in+the+path."/>';
}|code-block|syntax|javascript|636471|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|O|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|P|8|@]|9|@]|A|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

You are on the right track. You need to espace special characters in regext. the ? is a special character and should be escaped using the \?, also the dot should be escaped with slash too.

Finally, you should not use the \b option, it is not applicable in your situation.

Try:

<pre><code>if (!preg_match('/(\.php\?){1}/', $cfg_path))
{
 $error = true;
 echo '&lt;error elementid="cfg_path" message="PATH - make sure you have a \'.php?\' in the path."/&gt;';
}
</code></pre>

blocks|key|2703589|text|试试preg_match_all，它返回字符串中出现的次数。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2703590|if+(+preg_match_all+("~\.php\?~",+$cfg_path,+$match+)+>+1+){
++++$error+=+true;
++++echo+'<error+elementid="cfg_path"+message="PATH+-+make+sure+you+have+a+\'.php?\'+in+the+path."/>';
}|code-block|syntax|javascript|2703591|有关preg_match_all的更多信息，请单击此处PHP:+preg_match_all+-+Manual|2703592|但是，如果我编写这段代码，我就会完全避免使用正则表达式。喜欢|2703593|if+(++substr_count($cfg_path,+".php?")+>+1+){
++++$error+=+true;
++++echo+'<error+elementid="cfg_path"+message="PATH+-+make+sure+you+have+a+\'.php?\'+in+the+path."/>';
}|2703594|有关substr_count的更多信息，请点击此处：PHP:+substr_count+-+Manual|2703595|entityMap|0|LINK|mutability|MUTABLE|url|http://in2.php.net/manual/en/function.preg-match-all.php|1|http://in2.php.net/manual/en/function.substr-count.php^0|2|E|0|0|2|E|R|S|0|0|0|0|2|C|Q|Q|1|0^^$0|@$1|2|3|4|5|6|7|12|8|@$9|13|A|14|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|15|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|16|8|@$9|17|A|18|B|C]]|D|@$9|19|A|1A|1|1B]]|E|$]]|$1|M|3|N|5|6|7|1C|8|@]|D|@]|E|$]]|$1|O|3|P|5|H|7|1D|8|@]|D|@]|E|$I|J]]|$1|Q|3|R|5|6|7|1E|8|@$9|1F|A|1G|B|C]]|D|@$9|1H|A|1I|1|1J]]|E|$]]|$1|S|3|-4|5|6|7|1K|8|@]|D|@]|E|$]]]|T|$U|$5|V|W|X|E|$Y|Z]]|10|$5|V|W|X|E|$Y|11]]]]

try <code>preg_match_all</code>, which returns the number of occurrences in the string.

<pre><code>if ( preg_match_all ("~\.php\?~", $cfg_path, $match ) &gt; 1 ){
 $error = true;
 echo '&lt;error elementid="cfg_path" message="PATH - make sure you have a \'.php?\' in the path."/&gt;';
}
</code></pre>

More Information on <code>preg_match_all</code> here <a href="http://in2.php.net/manual/en/function.preg-match-all.php" rel="nofollow">PHP: preg_match_all - Manual</a>

But, if i was writing this code, i would have avoided the use of regex completly. like

<pre><code>if ( substr_count($cfg_path, ".php?") &gt; 1 ){
 $error = true;
 echo '&lt;error elementid="cfg_path" message="PATH - make sure you have a \'.php?\' in the path."/&gt;';
}
</code></pre>

More on <code>substr_count</code> here: <a href="http://in2.php.net/manual/en/function.substr-count.php" rel="nofollow">PHP: substr_count - Manual</a>

blocks|key|1668135|text|正如德米特里所说，你需要更多的逃脱。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1668136|正则表达式中的{1}不能确保一个模式在整个主题中只出现一次。它只是前一个字符串的量词。|offset|length|style|CODE|1668137|否则，手动检查匹配的频率：|1668138|preg_match_all("/(\.php\??)/",+$str,+$m);
$matched_once+=+count($m[1])+==+1;|code-block|syntax|javascript|1668139|如果要验证整个字符串，则必须指定完整的模式。使用%5E或$。例如，在您的案例中：|1668140|+preg_match("/\.php(\?[%5E?]*%7C)$/",+$str)|1668141|它要么匹配.php?...+(除了问号之外的所有内容)，要么在最后只匹配.php+($在正则表达式中标记结尾)。|1668142|entityMap^0|0|7|3|0|0|0|O|1|Q|1|0|0|5|8|10|4|16|1|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|X|8|@$D|Y|E|Z|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|10|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|11|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|6|7|12|8|@$D|13|E|14|F|G]|$D|15|E|16|F|G]]|9|@]|A|$]]|$1|Q|3|R|5|L|7|17|8|@]|9|@]|A|$M|N]]|$1|S|3|T|5|6|7|18|8|@$D|19|E|1A|F|G]|$D|1B|E|1C|F|G]|$D|1D|E|1E|F|G]]|9|@]|A|$]]|$1|U|3|-4|5|6|7|1F|8|@]|9|@]|A|$]]]|V|$]]

What Dmitri said, you need more escaping.

The <code>{1}</code> in regular expressions doesn't ensure that a pattern only occours once in the whole subject. It's a quantifier for the preceeding string only.

Otherwise check manually, how often it matched:

<pre><code>preg_match_all("/(\.php\??)/", $str, $m);
$matched_once = count($m[1]) == 1;
</code></pre>

If you want to validate the whole string, then you have to specify the complete pattern. Use <code>^</code> or <code>$</code>. For example in your case:

<pre><code> preg_match("/\.php(\?[^?]*|)$/", $str)
</code></pre>

Where it either matches <code>.php?...</code> (with everything but question marks following), or just <code>.php</code> at the very end (<code>$</code> marks the end in regular expressions).

blocks|key|636583|text|什么是不止一次？你声明你只想看一次。如果你不想看到的是连续的.php？.php？可能有更多的.php？是否可以在字符串中添加更多内容？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|636584|无论你如何看待一个子字符串，字符串的其他部分都对它有直接的影响。|636585|这就解决了这个问题：|636586|/%5E(((?!\.php\?).)*\.php\?){1}((?!\.php\?).)*$/|offset|length|style|CODE|636587|use+strict;
use+warnings;

my+@samples++=+(
+'form.php?category=something',
+'form.php?.php?category=something',+
+'form.php?category=something.php?',
+'.php?+form.php?category=something',
+'.php?+ok',
+'ok+.php?',
);

for+(@samples)
{
++++if+(+/%5E(((?!\.php\?).)*\.php\?){1}((?!\.php\?).)*$/x+)+{
++++++++print+"Once:++++$_\n\n";
++++}
++++else+{
++++++++print+"Failed:++$_\n\n";
++++}
}|code-block|syntax|javascript|636588|entityMap^0|0|0|0|0|1A|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|U|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|V|8|@$H|W|I|X|J|K]]|9|@]|A|$]]|$1|L|3|M|5|N|7|Y|8|@]|9|@]|A|$O|P]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

What is more than once? You state you only want to see it once. If what you don't want to
see is consecutive .php? .php? with possible more .php? will it be possible for more in the string?

No matter what you think when you look at a sub-string, there are the other parts of the string that have a direct influence on it.

This solves the problem: 
<code>/^(((?!\.php\?).)*\.php\?){1}((?!\.php\?).)*$/</code>

<pre><code>use strict;
use warnings;

my @samples = (
 'form.php?category=something',
 'form.php?.php?category=something', 
 'form.php?category=something.php?',
 '.php? form.php?category=something',
 '.php? ok',
 'ok .php?',
);

for (@samples)
{
 if ( /^(((?!\.php\?).)*\.php\?){1}((?!\.php\?).)*$/x ) {
 print "Once: $_\n\n";
 }
 else {
 print "Failed: $_\n\n";
 }
}
</code></pre>

how can I make sure a certain keyword just occurs once in the input with regular expression?

I think there is some mistakes in the expression below as I can repeat the same keywords,

<pre><code>if (!preg_match('/\b(.php?){1}\b/', $cfg_path))
 {
 $error = true;
 echo '&lt;error elementid="cfg_path" message="PATH - make sure you have a \'.php?\' in the path."/&gt;';
 }
</code></pre>

I just want this to be true,

<pre><code>form.php?category=something or form.php?
</code></pre>

but not this,

<pre><code>form.php?.php?category=something or form.php?.php?
</code></pre>

please let me know how to fix it.

thanks.

PHP & Regular expression: keyword just occurs once

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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如何确保某个关键字在使用正则表达式的输入中只出现一次？我认为下面的表达式中有一些错误，因为我可以重复相同的关键字，if (!preg_match('/\b(.php?){1}\b/', $cfg_path)) { $error = true; echo '<error elementi...

问PHP &正则表达式:关键字只出现一次
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