正则表达式在最后一次出现特殊字符后删除字符串

Question

I would like use of regex to remove string after some special symbols on last occurance. ie i am having string

Hello, How are you ? this, is testing

then i need output like this

Hello, How are you ? this

as these will be my special symbols , : : |

Answer 1

Why bother with a regex when normal string operations are perfectly fine?
EDIT; noticed how it not behave correctly with both : and , in the string.
This code will loop all chars and see which is last and substring it there. If there is no "chars" at all it will set $pos to strings full lenght (output full $str).

$str = "Hello, How are you ? this: is testing";
$chars = [",", "|", ":"];
$pos =0;
foreach($chars as $char){
    if(strrpos($str, $char)>$pos) $pos = strrpos($str, $char);
}
if($pos == 0) $pos=strlen($str);
echo substr($str, 0, $pos);

https://3v4l.org/XKs2Z

Answer 2

Use regex to split string (by special characters) into an array and remove the last element in array:

<?php
$string = "Hello, How are you ? this, is testing";
$parts = preg_split("#(\,|\:|\|)#",$string,-1,PREG_SPLIT_DELIM_CAPTURE);
$numberOfParts = count($parts);
if($numberOfParts>1) {
    unset($parts[count($parts)-1]); // remove last part of array
    $parts[count($parts)-1] = substr($parts[count($parts)-1], 0, -1); // trim out the special character
}
echo implode("",$parts);
?>