Weird behavior with strpos [duplicate]

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• How to make strpos case insensitive 3 answers

I'm programming an autocomplete system and i'm using strpos to look fo occurences of a given input in a txt file.

<?php
    $request=$_POST['req'];//the input received
    $file=fopen('file1.txt','r');
    $string='';
    while(($current=fgets($file))!==false){
         if (strpos($current,$request,0)!==false) {
             $string=$string.$current.'<br/>';
         }
    };
    fclose($file);
    echo $string;
?>

i don't know why , but it doesn't work properly when the given input is the start of string in the file. For example:Let's say that the file contains Metal Gear Solid on a line. If i type ' tal ' --> match found but If i type ' meta ' --> match not found.