PHP从模型内的控制器中的文件中查找字符串

I loading a file from a controller and trying to find a string from that file inside a model.

The function in the controller i have written has:

<?php
    public function file() {
        $filename = "C:/Users/Declan/Desktop/foo.txt";
    }
?>

And In the model I would have:

<?php
    function find{
        if( exec('grep '.escapeshellarg($_GET['bar']).'$filename')) {
            echo "string found";
        }
    }
?>

I am using This Question as reference.

Any help would be appreciated.

When you use the exec() method who is use to run an external program. You are on windows apparently, grep is only for unix system (Linux ...).

<?php
    function find($filePath, $stringToLookFor){
       $handle = fopen($filePath, 'r');

        $stringFound = false; // Init false
        while (($buffer = fgets($handle)) !== false) { // Loop through each file line
            if (strpos($buffer, $stringToLookFor) !== false) { // Check if in $buffer
                $stringFound = true; // String found
            }      
        }
        fclose($handle);
        return $stringFound;
    }
?>