php strpos总是返回false，我想得到一个正确的答案

Question

I get a project and i see a piece of code as follows:

<?php
$orderby=$_REQUEST['orderby'];
if(strpos($orderby,'d')===true){
    echo "exists";
}else{
    echo "not ";
}?>

In any case , i input 'd' or others parameters the page always returning 'not'. so, how to input correct parameter make the page returning 'exists'?

Answer 1

strpos() can never return TRUE. If the string is found it returns the position. If the string is not found it returns FALSE. So you should compare with FALSE, not TRUE.

if (strpos($orderby, 'd') === false) {
    echo "not exists";
} else {
    echo "exists";
}