php how to return only character value from the variable
===

i am using following code to return only digital values from the variable, wounder how to get only character value "testing" from the variable and want to remove "on" from the string.
    
    <?php
    $valuecheck="testing on 123568";
    $check1=preg_replace('/\D/', '', $valuecheck);
    echo $check1;
    ?>

Thanks



 

