Regular expression (php function), regularexpression_php tutorial

Regular expression (php function), regularexpression

1. Regular expressions are a tool for searching and matching strings

2. Regular expression functions commonly used in PHP

• Preg_match ($pattern, $subject)
• Preg_match_all ($pattern, $subject, array & $matches)
• Preg_replace ($pattern, $replacement, $subject)
• Preg_filter ($pattern, $replacement, $subject)
• Preg_grep ($pattern, array $input)
• Preg_split ($pattern, $subject)
• Preg_quote ($STR)

3. Function description

$pattern = Regular Expression

$subject = target function to match

(1) Preg_match () and Preg_match_all (): Return matches the number of results

• Preg_match ($pattern, $subject, [array & $matches]): Match only once with a result of 0 or 1, the third argument is not writable, the third parameter represents a reference to the address
• Preg_match ($pattern, $subject, Array & $matches): match all, result 0,1,2 ...

eg

$pattern = '/[0-9]/';

$subject = ' Weuyr3ui76as83s0ck9 ';

$m 1 = $m 2 = array ();

T1 = Grep_match ($pattern, $subject, $m 1);

T2 = Grep_match_all ($pattern, $subject, $m 2);

Result: M1 = array ([0]=>3)

m2 = Array ([0]=>array ([0]=>3,[1]=>7,[2]=>6,[3]=>8,[4]=>3,[5]=>0,[6]=>9))

T1 = 1

T2 = 7

(2) Preg_replace and Preg_filter: support for array substitution

• Preg_replace ($pattern, $replacement, $subject): Retains values that have been replaced and have not occurred
• Preg_filter ($pattern, $replacement, $subject): Retains the value of the substitution that occurred

eg one:

$pattern = '/[0-9]/';

$subject = ' Weuyr3ui76as83s0ck9 ';

$replacement = ' surplus ';

$str 1 = preg_replace ($pattern, $replacement, $subject);

$str 2 = Preg_filter ($pattern, $replacement, $subject);

Results:

$str 1 = ' Weuyr-ying UI yingying as Yingying S Ying ck ying '

$str 2 = ' Weuyr-ying UI yingying as Yingying S Ying ck ying '

Eg:

$pattern = Array ('/[0123]/', '/[456]/', '/[789]/')

$replacement = Array (' Ah ', ' la ', ' winded ')

Results:

$str 1 = ' Weuyr Ah, the UI is winded as a, s ah ck '

$str 2 = ' Weuyr Ah, the UI is winded as a, s ah ck '

EG three:

$subject = Array (' Weuy ', ' r3ui ', ' 76as83 ', ' s ', ' 0ck9 ');

Results:

$str 1 = Array ([0]=>weuy, [1]=>r] UI, [2]=>, [3]=>s, [4]=>, CK)

$str 2 = Array ([1]=>r UI, [2]=>, [4]=>, CK)

(3) Grep_grep ($pattern, array $input): Castrated version of Grep_filter (), do only match, do not replace

eg

$pattern = '/[0-9]/';

$subject = Array (' Weuy ', ' r3ui ', ' 76as83 ', ' s ', ' 0ck9 ');

$arr = Preg_grep ($pattern, $subject);

Results:

$arr = Array ([1]=>r3ui, [2]=>76as83, [4]=>0ck9)

(4) Grep_split ($pattern, $subject): Explode is a subset of the function

eg

$pattern = '/[0-9]/';

$subject = ' You 2 good 3 Ah! '

$arr = Preg_split ($pattern, $subject);

Results:

$arr = ([0]=> you, [1]=> good, [2]=> Ah!)

　　

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