How to find a part of string in a string - PHP Snippet

This php function searches a part of string inside a large string, return true if found.

function strinstr($find, $str){ 
    $find = preg_quote($find); 
    if(preg_match('~'.$find.'~',$str)){ 
        return TRUE; 
    } 
    return FALSE; 
} 

//exemple of use
$sStr = 'hello my name is billy bob joe.'; 

if(strinstr('ralph', $sStr)) 
    echo 'found'; 
else 
    echo 'not found';