- var_dump: documentation ( source)
- strpos: documentation ( source)
<?php
$strselvaluelist = "4";
if(!empty($strselvaluelist)){
echo 0;
if(strpos("4", $strselvaluelist)){
echo 1;
if(!strpos("17", $strselvaluelist)){
$strselvaluelist.='|17';
echo 2;
}
}
}
var_dump($strselvaluelist);