PHP construct not echoing variables

Question

I'm new to PHP so still getting grips of how constructs work and I'd appreciate some help!

The following code is failing to echo the variables $arrivalTime and $hourStay:

class Variable {

public $arrivalTime;
public $hourStay;   

public function __construct() {
    $this->arrivalTime = $_POST['arrivalTime'];
    $this->hourStay = $_POST['hourStay'];

    echo $this->arrivalTime;
    echo $this->hourStay;
}
}

I couldn't tell without seeing the bigger picture... You can pass them like that or, in my oppinion better, as input in the constructor if you don't want the class to be dependent to post values. — Cosmin
– Cosmin, Commented Oct 29, 2015 at 15:25

CompuChip · Accepted Answer · 2015-10-29 15:31:08Z

3

You need to instantiate the class, by calling new Variable() somewhere in your code. However, in general it is better to not have your class depend on the post variables, but pass them in through the constructor:

class Variable {

  public $arrivalTime;
  public $hourStay;   

  public function __construct($arrivalTime, $hourStay) {
      // TODO: Check if the values are valid, e.g.
      // $arrivalTime is a time in the future 
      // and $hourStay is an integer value > 0.
      $this->arrivalTime = $arrivalTime;
      $this->hourStay = $hourStay;
  }

  public function print() {
      echo $this->arrivalTime;
      echo $this->hourStay;
  }
}

$var = new Variable($_POST['arrivalTime'], $_POST['hourStay']);
$var->print();

Also note how I took the generation of output away from the constructor. Its only task should be to initialize the object to a valid state. Processing input or generating output is not its responsibility.

answered Oct 29, 2015 at 15:31

CompuChip

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2 Comments

Liam Macmillan Over a year ago

Thanks a lot, exactly what I was looking for. To get each variable individually, would this be a good way of doing so?: pastie.org/pastes/10516156/text

CompuChip Over a year ago

I would include validation in the constructor to make sure that arrival time and hour stay are valid, and move the calculation of the pickup time to the getter: public function get_pickupTime() { return date('H:i', (strtotime($this->arrivalTime) + $this->hourStay)); }

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