PHP and Reference Operator &

Overview

• Scalars are passed by values
• To pass Scalars by reference you need to use the & Reference Operator
• Objects are passed by Reference

PHP sample Code

class WRLoginObj {
    public $pvName = "";
    public $isOnline = false;
    
    function  __construct($pvName, $isOnline ) {
        $this->pvName = $pvName;
        $this->isOnline = $isOnline;
        }
}

$wrLoginObjArr = [];
initApp();
function initApp() {
	$isOnline = "false";
	$wrLoginObjArr = [];
	$wrLoginObj = new WRLoginObj("PV1", "false"  );
    array_push( $wrLoginObjArr, $wrLoginObj );
    $wrLoginObj = new WRLoginObj("PV2", "false"  );
    array_push( $wrLoginObjArr, $wrLoginObj );
    
    echo("Object Test: Objects/Arrays are passed by reference\n");
    dumpObjData($wrLoginObjArr);
    changeObjData($wrLoginObjArr);
    dumpObjData($wrLoginObjArr);
    
    echo("Scalar before changeSclar() [ Original Value ] - isOnline:  " .$isOnline . "\n"  );
    changeSclarCopyByWrite($isOnline);
    echo("Scalar after changeSclarCopyByWrite [ Nothing changed ]  - isOnline:  " .$isOnline . "\n" );
    changeScalarbyRef($isOnline);
    echo("Scalar after changeScalarByRef() [ Changed value ] - isOnline:  " .$isOnline . "\n" );
}        

function changeScalarByRef(&$val) {
	$val = "true";
}

function changeSclarCopyByWrite($val) {
	$val = "true";
}

function dumpObjData($loginArr) {
	foreach ($loginArr as $loginObj) {
		echo ("pvName: " . $loginObj->pvName . "  - Status:  ". $loginObj->isOnline . "\n") ;
	}
}	

function changeObjData($loginArr) {
	foreach ($loginArr as $loginObj) {
		$loginObj->isOnline = "true";
	}
}

PHP Program Output

D:\xampp\htdocs\tc>  php objRef.php 
Object Test: Objects/Arrays are passed by reference
pvName: PV1  - Status:  false
pvName: PV2  - Status:  false
pvName: PV1  - Status:  true
pvName: PV2  - Status:  true
Scalar before changeSclar() [ Original Value ] - isOnline:  false
Scalar after changeSclarCopyByWrite [ Nothing changed ]  - isOnline:  false
Scalar after changeScalarByRef() [ Changed value ] - isOnline:  true