{"id":2686,"date":"2021-09-13T09:19:40","date_gmt":"2021-09-13T09:19:40","guid":{"rendered":"https:\/\/phptutorial.net\/php-tutorial\/regex-alternation\/"},"modified":"2025-04-07T13:25:42","modified_gmt":"2025-04-07T13:25:42","slug":"regex-alternation","status":"publish","type":"page","link":"https:\/\/www.phptutorial.net\/php-tutorial\/regex-alternation\/","title":{"rendered":"Regex Alternation"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn about regex alternation, which is simply an “OR” operator in the regular expression.<\/p>\n\n\n\n

Introduction to the regex alternation #<\/a><\/h2>\n\n\n\n

Regular expressions<\/a> use the pipe character (|<\/code>) to denote an alternation. The alternation is simple the OR<\/code> operator in the regular expressions.<\/p>\n\n\n\n

For example, the following pattern uses the alternation (|<\/code>) to match apple<\/code> or orange<\/code>:<\/p>\n\n\n

'\/apple|orange\/'<\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Here’s the code:<\/p>\n\n\n
<?php<\/span>\n\n$str = \"apple, orange, banana\"<\/span>;\n$pattern = '\/apple|orange\/'<\/span>;\n\nif<\/span> (preg_match_all($pattern, $str, $matches)) {\n    print_r($matches[0<\/span>]);\n}<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
Array<\/span>\n(\n    [0<\/span>] => apple\n    [1<\/span>] => orange\n)<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Use the regex alternation for matching time in hh:mm format #<\/a><\/h2>\n\n\n\n
To match a time in hh:mm<\/code>, you can use the following regular expression:<\/p>\n\n\n
'\/\\d{2}:\\d{2}\/'<\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
However, the\\d{2}<\/code> pattern also matches 99<\/code>, which is not a valid hour or minute.<\/p>\n\n\n\n
To fix this, you can use the regex alternation. The valid hour ranges from 01<\/code> to 23<\/code>. Therefore, the pattern for matching the hour is as follows:<\/p>\n\n\n
[01<\/span>]\\d|2<\/span>[0<\/span>-3<\/span>]<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The minute ranges from 00<\/code> to 59<\/code>. So the pattern for the minute is:<\/p>\n\n\n
[0<\/span>-5<\/span>]\\d<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Here’s the regular expression that matches the time in the hh:mm<\/code> format:<\/p>\n\n\n
'\/[01]\\d|2[0-3]:[0-5]\\d\/'<\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Also, you can add the capturing groups for both hour and minute:<\/p>\n\n\n
'\/([01]\\d|2[0-3]):([0-5]\\d)\/'<\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
The following example illustrates how to use the regex alternation to match the time:<\/p>\n\n\n
<?php<\/span>\n\n$times = ['10:20'<\/span>, '24:10'<\/span>, '01:20'<\/span>, '22:99'<\/span>];\n$pattern = '\/([01]\\d|2[0-3]):([0-5]\\d)\/'<\/span>;\n\nforeach<\/span> ($times as<\/span> $time) {\n    if<\/span> (preg_match($pattern, $time, $matches)) {\n        echo<\/span> $matches[0<\/span>] . PHP_EOL;\n    }\n}<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
10<\/span>:20<\/span>\n01<\/span>:20<\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Summary #<\/a><\/h2>\n\n\n\n
    \n
  • The regex alternation is an OR operator in regular expressions.<\/li>\n<\/ul>\n
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    Did you find this tutorial useful?<\/div>\n\t\t
    \n\t\t\t\n\t\t\t\t\n\t\t\t\t\t<\/path>\n\t\t\t\t<\/svg>\n\t\t\t\t Yes <\/span>\n\t\t\t<\/button>\n\n\t\t\t\n\t\t\t\t\n\t\t\t\t\t<\/path>\n\t\t\t\t<\/svg>\n\t\t\t\t No <\/span>\n\t\t\t<\/button>\n\t\t<\/div>\n\t<\/header>\n\n\t
    \n\t\t
    \n\t\t\t
    <\/div>\n\t\t\t\n\t\t\t
Try it<\/a><\/p>\n\n\n\n
Try it<\/a><\/p>\n\n\n\n