从字符串 PHP 中删除前 3 个字符和后 3 个字符

Delete first 3 characters and last 3 characters from String PHP

提问by Howdy_McGee

I need to delete the first 3 letters of a string and the last 3 letters of a string. I know I can use substr() to start at a certain character but if I need to strip both first and last characters i'm not sure if I can actually use this. Any suggestions?

我需要删除字符串的前 3 个字母和字符串的后 3 个字母。我知道我可以使用 substr() 从某个字符开始，但是如果我需要去掉第一个和最后一个字符，我不确定我是否真的可以使用它。有什么建议？

回答by Sean Bright

Pass a negative value as the lengthargument (the 3rd argument) to substr(), like:

将负值作为length参数（第三个参数）传递给substr()，例如：

$result = substr($string, 3, -3);

So this:

所以这：

<?php
$string = "Sean Bright";
$string = substr($string, 3, -3);
echo $string;
?>

Outputs:

输出：

n Bri

回答by James

Use

用

substr($var,1,-1)

this will always get first and last without having to use strlen.

这将始终是第一个和最后一个，而不必使用 strlen。

Example:

例子：

<?php
    $input = ",a,b,d,e,f,";
    $output = substr($input, 1, -1);
    echo $output;
?>

Output:

输出：

a,b,d,e,f

a,b,d,e,f

回答by mgutt

As stated in other answers you can use one of the following functions to reach your goal:

如其他答案所述，您可以使用以下功能之一来实现您的目标：

• substr($string, 3, -3)removes 3 chars from start and end
• trim($string, ",")removes all specific chars from start and end
• ltrim($string, ".")removes all specific chars from start
• rtrim($string, ";")removes all specific chars from end

• substr($string, 3, -3)从开头和结尾删除 3 个字符
• trim($string, ",")从开始和结束删除所有特定字符
• ltrim($string, ".")从头开始删除所有特定字符
• rtrim($string, ";")从末尾删除所有特定字符

It depends on the amount of chars you need to remove and if the removal needs to be specific. But finally substr()answers your question perfectly.

这取决于您需要删除的字符数量以及删除是否需要具体。但最终substr()完美地回答了你的问题。

Maybe someone thinks about removing the first/last char through string dereferencing. Forget that, it will not work as nullis a char as well:

也许有人考虑通过string dereferencing删除第一个/最后一个字符。忘记这一点，它也不会像null字符那样工作：

<?php
$string = 'Stackoverflow';
var_dump($string);
$string[0] = null;
var_dump($string);
$string[0] = null;
var_dump($string);
echo ord($string[0]) . PHP_EOL;
$string[1] = '';
var_dump($string);
echo ord($string[1]) . PHP_EOL;
?>

returns:

返回：

string(13) "Stackoverflow"
string(13) "tackoverflow"
string(13) "tackoverflow"
0
string(13) "ackoverflow"
0

And it is not possible to use unset($string[0])for strings:

并且不能unset($string[0])用于字符串：

Fatal error: Cannot unset string offsets in /usr/www/***.phpon line **

致命错误：无法在/usr/www/***.php线上取消设置字符串偏移量**

回答by Maxim Krizhanovsky

substr($string, 3, strlen($string) - 6)

回答by Antony Scott

I don't know php, but can't you take the length of the string, start as position 3 and take length-6 characters using substr?

我不知道 php，但你不能取字符串的长度，从位置 3 开始并使用 substr 取长度为 6 个字符吗？

回答by Jonathan M

$myString='123456789';
$newString=substr($myString,3,-3);