- substr: documentation ( source)
- strpos: documentation ( source)
<?php
$p_field_type = "select{m,f}";
if(strpos($p_field_type, "{")!==FALSE && strpos($p_field_type, "}")!==FALSE) { echo "huzza!"; } else { echo "nuuuuh!"; }
echo "<br>";
echo substr($p_field_type, strpos($p_field_type, "{")+1, -1);