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regular expression (php函数),regularexpression

WBOY
WBOY原創
2016-06-13 08:44:29944瀏覽

regular expression (php函数),regularexpression

1. 正则表达式是一种字符串搜索和匹配的工具

2. php中常用正则表达式函数

  • 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. 函数说明

$pattern = 正则表达式

$subject = 匹配的目标函数

  (1) preg_match() 和 preg_match_all() : return 匹配到结果的次数

  • preg_match($pattern, $subject, [array &$matches]) : 只匹配一次, 结果为0或者1, 第三个参数可不写, 第三个参数表示地址的引用
  • preg_match($pattern, $subject, array &$matches) : 匹配全部, 结果为0,1,2......

  eg:

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

    $subject = 'weuyr3ui76as83s0ck9';

    $m1 = $m2 = array();

    t1 = grep_match($pattern, $subject, $m1);

    t2 = grep_match_all($pattern, $subject, $m2);

  结果: 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 与 preg_filter : 支持数组替换

  • preg_replace($pattern, $replacement, $subject) : 保留发生替换和没发生替换的值
  • preg_filter($pattern, $replacement, $subject) : 保留发生替换的值

  eg one:

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

    $subject = 'weuyr3ui76as83s0ck9';

    $replacement = '盈';

    $str1 = preg_replace($pattern, $replacement, $subject);

    $str2 = preg_filter($pattern, $replacement, $subject);

  结果:

    $str1 = 'weuyr盈ui盈盈as盈盈s盈ck盈'

    $str2 = 'weuyr盈ui盈盈as盈盈s盈ck盈'

  eg two:

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

    $replacement = array('啊', '啦', '嗦')

  结果:

    $str1 = 'weuyr啊ui嗦啦as嗦啊s啊ck嗦'

    $str2 = 'weuyr啊ui嗦啦as嗦啊s啊ck嗦'

  eg three:

    $subject = array('weuy', 'r3ui', '76as83', 's', '0ck9');

  结果:

    $str1 = array([0]=>weuy, [1]=>r啊ui, [2]=>嗦啦as嗦啊, [3]=>s, [4]=>啊ck嗦)

    $str2 = array([1]=>r啊ui, [2]=>嗦啦as嗦啊, [4]=>啊ck嗦)

  (3) grep_grep($pattern, array $input) : 阉割版的grep_filter(), 只做匹配, 不做替换

  eg:

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

    $subject = array('weuy', 'r3ui', '76as83', 's', '0ck9');

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

   结果:

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

  (4) grep_split($pattern, $subject) : explode是该函数的子集

  eg:

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

    $subject = '你2好3啊!'

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

  结果:

    $arr = ([0]=>你, [1]=>好, [2]=>啊!)

  

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