PHP：在类中使用isset（）函数

Question

I am into procedural programming and new to OOP. With the following code, I would like to print a message "Submitted successfully" on clicking submit button. But it is not happening. In the procedural programming I do something like isset($_POST[$name]). Here how to refer button name?

<?php

//myclass

class InsertData {
    public $txtwidth;
    public $txtheight;
    public $txtname;
    public $btnwidth;
    public $btnheight;
    public $btnname;

    function setTextField($tw, $th, $tname) {
        $this->txtwidth = $tw;
        $this->txtheight =$th;
        $this->txtname = $tname;        
    }

    function setButton($bw, $bh, $bname) {
        $this->btnwidth = $bw;
        $this->btnheight =$bh;
        $this->btnname = $bname;
    }

function displayText() {
    if(isset($_POST[$this->btnname])) {         
            echo "Submitted successfully";
        }
}
    function getTextField() {
        $str = "<form name='inputform' action='#' method='post'>
        <input type='text' name='".$this->txtname."' Style=width:".$this->txtwidth."px;height:".$this->txtheight."px><br><br>
         <input type='submit' name='".$this->btnwidth."' Style=width:".$this->btnheight."px;height:".$this->btnname."px>
         </form>";  


        return $str;
    }

}
?>

My code

<?php

//my code

include "InsertData.php";
$txt = new InsertData();

$txt->setTextField(800,200,'yourname');
$txt->setButton(100, 200, 'click');
echo $txt->getTextField();
echo $txt->displayText();
?>

Answer 1

Just modify function displayText() to

function displayText() {
  return "Submitted successfully";
}

And on submit do a ,

if(isset($_POST['your_btn_name'])) {   
  echo  $txt->displayText();    
}