如何从php中同一个类中的另一个函数调用公共函数中的变量

Question

<?php  
class Pen  
{  
    public $color;  
    public function clr()  
    {  
        $this->color = "Red";  
    }  
    public function write()  
    {  
        echo $this->color; //if i write $ before color it gives me an error
    }  
}  
$a = new Pen();  
$a->write();  
?>

i tried to write an $ dollar in the write() function but it gives me an error and in this code it shows nothing i even tried to use "class name :: function name ()-> color ;" didn't work either i tried a lot of things that i found here but none of them really worked for me

Answer 1

You are close ...

<?php  
class Pen  
{  
    public $color;  

    // Constructor, this is called when you do a new
    public function __construct($color = null)  
    {  
        // Call setColor to set the color
        $this->setColor($color);  
    } 

    // Method to set the color
    public function setColor($color) {
        $this->color = $color;
    } 

    // Write out the color
    public function write()  
    {  
        echo $this->color; 
    }  
}  

// Construct a new red pen
$a = new Pen('red');  

// Write with it
$a->write();  

// Change the color to blue
$a->setColor('blue');

// Write with it
$a->write();
?>

Take some time to read about PHP classes and objects at php.net.