The specified character of the variable in php Regular Expression replacement

The following three implementations are used to introduce the specified characters of variables in php Regular Expression replacement. For more information, see.

Three methods.

1.

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<? Php $ Str = preg_quote ('(silver )'); $ Txt = 'My name (silver )'; Echo preg_replace ("/($ str)/", "<span style = 'color: # f00; '> $1 </span>", $ txt ); ?>

2.

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<? Php $ Str = quotemeta ('(silver )'); $ Txt = 'My name (silver )'; Echo preg_replace ("/($ str)/", "<span style = 'color: # f00; '> $1 </span>", $ txt ); ?>

3.

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<? Php $ Str = '(silver )'; $ Txt = 'My name (silver )'; Echo preg_replace ("/(Q $ strE)/", "<span style = 'color: # f00; '> $1 </span>", $ txt ); ?>

All three methods return the same result. The Perl-style Regular Expression in PHP is exactly the same as that in Perl. quotemeta is also common ..

Some other regular expressions

Example:

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$ Text = "foobar123fooabcbar "; $ Text = preg_replace ("/foo (? = Bar)/"," *** ", $ text );

// Match the position in front of bar *** bar123fooabcbar

 

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$ Text = "foobar123fooabcbar "; $ Text = preg_replace ("/(? <= Bar) 123/"," *** ", $ text );

// Match the location foo behind the bar *** 123 fooabcbar

 

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$ Text = "foobar123fooabcbar "; $ Text = preg_replace ("/foo (?! Bar)/"," *** ", $ text );

// Match the position behind the bar instead of foobar123 *** abcbar

 

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$ Text = "foobar123fooabcbar "; $ Text = preg_replace ("/(? <! Foo) bar/"," *** ", $ text );

// Match foobar123fooabc, which is not the position of foo ***