Detailed explanation of the usage of value transfer/reference transfer between PHP custom functions

php:Parameter transfer between functions

1. Value transfer

<?php 
function exam($var1){ 
$var1++； 
echo
 "In Exam:" . $var1 . "<br />"; 
} 
$var1 = 1; 
echo $var1 . "<br />"; 
exam($var1); 
echo $var1 . "<br />"; 
?>

------------------------------------------------ -------------------------------
Output results:
1
In Exam: 2
1
---------------------------------------------- ----------------------------------
2.QuoteTransfer

<?php 
function exam( &$var1){ 
$var1++； 
echo "In Exam:" . $var1 . "<br />"; 
} 
$var1 = 1; 
echo $var1 . "<br />"; 
exam($var1); 
echo $var1 . "<br />"; 
?>

----------------------------------------- ---------------------------------------------
Output result:
1
In Exam: 2
2
--------------------------------------------- ----------------------------------------
3.Yes Select parameter

function values($price, $tax=""){ 
$price += $prive * $tax; 
echo "Total Price:" . $price . "<br />"; 
} 
values(100, 0.25); 
values(100);

Output result:
Total Price: 125
Total Price: 100
------------------ -------------------------------------------------- -----------
4. If a object is passed in, the value of the object can be changed
(actually Variable$obj records the handle of this object. Passing $obj as a parameter can completely operate on the original object)

<?php 
class
 Obj{ 
public $name; 
public $age; 
public $gander; 
public function construct($name, $age, $gander){ 
$this->name = $name; 
$this->age = $age; 
$this->gander = $gander; 
} 
public function show_info(){ 
echo $this->name . " " . $this->age . " " . $this->gander . "<br />"; 
} 
} 
function grow($obj){ 
$obj->age++; 
} 
function test(){ 
$obj = new Obj("Mr. zhan", "12", "male"); 
$obj->show_info(); 
grow($obj); 
$obj->show_info(); 
grow($obj); 
$obj->show_info(); 
} 
test(); 
?>

----------- -------------------------------------------------- ------------------
Output result:
Mr. zhan 12 male
Mr. zhan 13 male
Mr. zhan 14 male

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