Arguments between php functions pass of values pass and reference passes

php: Parameter passing between functions

1. The value

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

$var1 = 1; 
echo $var1 . "<br />"; 
exam($var1); 
echo $var1 . "<br />"; 
?> 

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Output results:
1
In Exam: 2
1
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2. Reference passing

 
<?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
2
-------------------------------------------------------------------------------
3. Optional parameters

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

values(100, 0.25); 
values(100); 

Output results:
Total Price: 125
Total Price: 100
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4. If you pass in an object, you can change the value of that object
(The variable $obj actually records the handle to this object, passing in $obj as a parameter, which allows you to manipulate 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(); 
?> 

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Output results:
Mr. zhan 12 male
Mr. zhan 13 male
Mr. zhan 14 male