Classes PHP5 avec sql server 2012

Bonjour,
Je developpe une application php , et je suis demandée de la transformer en php5 et changer le tout en classes et objets , mais j'ai pas réussi à le faire, ça m'affiche toujours l'erreur suivante :
Undefined variable conn ..., voici le code de la classe connect.php

<?php
class Connect
{
	public $serverName;
	public $Database;
	public $CharacterSet;
	public $UID;
	public $PWD;
	public function __construct()
	{
		$serverName="192.168....";		 
		$connectionInfo=array( "Database"=>"..." , "CharacterSet"=>"UTF-8","UID"=>"...", "PWD"=>"...");
		$conn=sqlsrv_connect($serverName,$connectionInfo);		
        if($conn===false)
        {
      	  die(print_r(sqlsrv_errors(),true));
        }       
	} 
}
$c=new Connect;
?>

Maintenant j'ai essayé de créer une classe , voici le code :

<?php
include ("connect.php");
class GP_Rattachement
{
	private $NIntervention;
	private $DateIntervention;
	private $NChantier;
	private $CClient;
	private $Cout;
	private $Nature;
	private $Responsable;
	private $HeureDebut;
	private $HeureFin;
	private $Emplacement;
	private $Reference;
	private $NBonLivraision;
	private $NFacture;
	private $RaisonSociale;
	private $TypeIntervention;
	private $Cloture;
	private $DateCloture;
	private $CoutRH;
	private $CoutAR;
	private $CoutCD;
	private $CoutDevis;
	private $EmplacementBC;
	private $NBC;
	private $DateBC;
	private $MtHtBC;
	private $MtFact;
	private $Remarque;
	private $EstJours;
	private $EstJoursNume;
	private $CreePar;
	private $ModifiePar;
	private $DateInsertion;
	private $DateModification;
	private $PCInsertion;
	private $PCModification;
	private $Indice;


	public function __construct($di=null, $nch=null, $ccli=null, $cou=null, $nat=null, $resp=null, $hdeb=null, $hfin=null, $empl=null, $ref=null, $nbl=null, $nfac=null, $rs=null, $typi=null, $clo=null, $dateclo=null,$crh=null,
	 $car=null,$ccd=null,$cdevis=null,$empbc=null, $nbc=null, $datbc=null, $mhbc=null, $mf=null, $rem=null, $ej=null, $ejn=null, $crp=null, $modifp=null, $datinsert=null, $datmodif=null, $pcinsert=null, $pcmodif=null, $ind=null)
	{
		$this->DateIntervention=$di;
		$this->NChantier=$nch;
		$this->CClient=$ccli;
		$this->Cout=$cou;
		$this->Nature=$nat;
		$this->Responsable=$resp;
		$this->HeureDebut=$hdeb;
		$this->HeureFin=$hfin;
		$this->Emplacement=$empl;
		$this->Reference=$ref;
		$this->NBonLivraision=$nbl;
		$this->NFacture=$nfac; 
		$this->RaisonSociale=$rs;
		$this->TypeIntervention=$typi;
		$this->Cloture=$clo;
		$this->DateCloture=$dateclo;
		$this->CoutRH=$crh;
		$this->CoutAR=$car;
		$this->CoutDevis=$ccd;
		$this->EmplacementBC=$empbc;
		$this->NBC=$nbc;
		$this->DateBC=$datbc;
		$this->MtHtBC=$mhbc;
		$this->MtFact=$mf;
		$this->Remarque=$rem;
		$this->EstJours=$ej;
		$this->EstJoursNume=$ejn;
		$this->CreePar=$crp;
		$this->ModifiePar=$modifp;
		$this->DateInsertion=$datinsert;
		$this->DateModification=$modifp;
		$this->PCInsertion=$pcinsert;
		$this->PCModification=$pcmodif;
		$this->Indice=$ind;
	}
public function Ajouter_Intervention($chNumInterAInserer,$dd,$nch,$codeclient,$cout, $nat,$resp,$hd,$hf,$emplacement,$ref,$nbl,$nfact,$rs,$ti,$clo,$df,$coutrh,$coutar,$coutcd,$coutdev,$emplbc,$nbc,$datebc,$mtht,$mtfact,$obs,$ej,$ejn,$crep,$modp,$dinsert,$dmodif,$pcinsert,$pcmodif,$indice)
	{
		$sqlinsertintervention="insert into GI_Intervention values ('$chNumInterAInserer','$dd','$nch','$codeclient','cout','$nat','$resp','$hd','$hf','$emplacement','$ref','$nbl','$nfact','$rs','$ti','$clo','$df','$coutrh','$coutar','$coutcd','$coutdev','$emplbc','$nbc','$datebc','$mtht','$mtfact','$obs','$ej','$ejn','$crep','$modp','$dinsert','dmodif','$pcinsert','$pcmodif','$indice')";
        $resultinsertion=sqlsrv_query($conn,$sqlinsertintervention);
        if($resultinsertion===false)
         {
            die(print_r(sqlsrv_errors(),true));

         }
       else 
        {
          echo "<br>insertion bien effectuee<br>";

        }
	}

function Modifier_Intervention($chNumInterAInserer,$dd,$nch,$codeclient,$cout,$nat,$resp,$hd,$hf,$emplacement,$ref,$nbl,$nfact,$rs,
		$ti,$clo,$df,$coutrh,$coutar,$coutcd,$coutdev,$emplbc,$nbc,$datebc,$mtht,$mtfact,$obs,$ej,$ejn,$crep,$modp,$dinsert,$dmodif,$pcinsert,$pcmodif,$indice)
	{
		$sqlModif="update GI_Intervention set DateIntervention='$dd',NChantier='$nch',CClient='$codeclient',Cout='$cout',Nature='$nat',Responsable='$rs',HeureDebut='$hd',HeureFin='$hf',Emplacement='$empl',Reference='$ref',NBonLivraision='$nbl',NFacture='$nfact',RaisonSociale='$rs',
		 TypeIntervention='$ti',Cloture='$clo',DateCloture='$df',CoutRH='$coutrh',CoutAR='$coutar',CoutDevis='$coutdev',EmplacementBC='$emplbc',NBC='nbc', DateBC='$datebc',MtHtBC='$mtht',MtFact='mtfact',Remarque='$obs',EstJours='$ej', EstJoursNume='ejn',CreePar='crep', ModifiePar='modp',DateInsertion='$dinsert',DateModification='$dmodif',PCInsertion='$pcinsert', PCModification='$pcmodif', Indice='$indice' where NIntervention='$chNumInterAInserer'";

        $stmtModif=sqlsrv_query($conn, $sqlModif);
      if($stmtModif===true)

      { 
      	echo"La mise à jour est effectuée avec succes";    

      }
      else
     echo "La modification a echoue ";
	}

	function Supprimer_Intervention($chNumInterAInserer)
	{
		$SqlSupp="delete from GI_Intervention where NIntervention='$chNumInterAInserer'";
		$stmt_supp=sqlsrv_query($conn,$SqlSupp);
		$row=sqlsrv_fetch_array($stmt_supp,SQLSRV_FETCH_NUMERIC);
		echo "Suppression effectuée avec succès";
	}

	function lister_Intervention()
	{		
		$sql_lister="select * from GP_Rattachement ";
		$stmt_lister=sqlsrv_query($conn,$sql_lister);
		while($rslt_lister=sqlsrv_fetch_array($stmt_lister, SQLSRV_FETCH_NUMERIC))
		{
			echo "<br>N° Rattachement : ".$rslt_lister[0]."<br>";
			echo "Raison Sociale : ".$rslt_lister[14]."<br>";
		}
	}

}
?>
<?php
$gpr= new GP_Rattachement;
$l=$gpr->lister_Intervention();
var_dump($l);
?>