PHP ltrim行为与字符列表 [英] PHP ltrim behavior with character list

问题描述

我试图使用php ltrim函数实现从字符串中剥离一些开头部分.它可以正常工作直到在冒号后加上一个i字符.如果在冒号之后找到i，则只需忽略i字符.我知道可以用substr或任何其他方式来完成它，但是我想知道为什么它会随着修剪发生.例如.

I was trying to achieve stripping off some beginning part from a string using php ltrim function. It works fine until it get a i character after colon : . if it find i after colon it simply ignore the i character. I know it can be done with substr or any other way but I want to know why its happening with trim. For example.

ltrim('mailto:[e-mail]','mailto:');

上面的函数将返回[e-mail]

the above function will return [e-mail]

但是如果我把我放在冒号后面..

but if I put i after colon.. for example

ltrim('mailto:[e-mail]','mailto:');

这将返回[e-mail]

this one will return [e-mail]

有人可以解释发生了什么事吗?

Can anybody explain what is happening?

推荐答案

ltrim的第二个参数是要从字符串左侧删除的字符列表.

The second argument to ltrim is a list of characters to remove from the left side of the string.

如果您这样做

<?php
    ltrim('lllliiiiaaaaaatttttt', 'mailto:');
?>

您将获得一个空字符串作为返回值.

You would get an empty string as the return value.

尝试以下方法:

<?php
    $email = 'mailto:[e-mail]';
    $fixedEmail = substr($email, 0, 7) == 'mailto:' ? substr($email, 7) : $email;
?>

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