PHP - add underscores before capital letters

混江龙づ霸主 提交于 2019-12-05 09:59:31

问题


How can I replace a set of words that look like:

SomeText

to

Some_Text

?


回答1:


This can easily be achieved using a regular expression:

$result = preg_replace('/\B([A-Z])/', '_$1', $subject);

a brief explanation of the regex:

  • \B asserts position at a word boundary.
  • [A-Z] matches any uppercase characters from A-Z.
  • () wraps the match in a back reference number 1.

Then we replace with '_$1' which means replace the match with an [underscore + backreference 1]




回答2:


$s1 = "ThisIsATest";
$s2 = preg_replace("/(?<=[a-zA-Z])(?=[A-Z])/", "_", $s1);

echo $s2;  //  "This_Is_A_Test"

Explanation:

The regex uses two look-around assertions (one look-behind and one look-ahead) to find spots in the string where an underscore should be inserted.

(?<=[a-zA-Z])   # a position that is preceded by an ASCII letter
(?=[A-Z])       # a position that is followed by an uppercase ASCII letter

The first assertion makes sure that no underscore is inserted at the start of the string.




回答3:


The simplest way to do this is with a regular expression replacement.

For example:

substr(preg_replace('/([A-Z])/', '_$1', 'SomeText'),1);

The substr call there is to remove a leading '_'




回答4:


<?php 

$string = "SomeTestString";
$list = split(",",substr(preg_replace("/([A-Z])/",',\\1',$string),1));
$text = "";

foreach ($list as $value) {
    $text .= $value."_";
}

echo substr($text,0,-1); // remove the extra "_" at the end of the string

?>



回答5:


$result = strtolower(preg_replace('/(.)([A-Z])/', '$1_$2', $subject));

Converts:

HelloKittyOlolo
Declaration
CrabCoreForefer
TestTest
testTest

To:

hello_kitty_ololo
declaration
crab_core_forefer
test_test
test_test


来源:https://stackoverflow.com/questions/6227061/php-add-underscores-before-capital-letters

易学教程内所有资源均来自网络或用户发布的内容,如有违反法律规定的内容欢迎反馈
该文章没有解决你所遇到的问题?点击提问,说说你的问题,让更多的人一起探讨吧!