欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页  >  php教程

regular expression (php函数) - yanying12138

程序员文章站 2022-04-15 22:22:03
...
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. php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!)

  (5) grep_quote($str) : 正则运算符转义

  eg:

        $str = 'asgs{kkk}[123]'
        $str = grep_quote($str)    

  结果:

    asgs\{kkk\}\[123\]