函数和if中的其他PHP

问题描述：

i dont understand how the if statement works and the function is called, why i am getting "He has more strength", i know because the strength is greater, but what i am getting there, is it a boolean? can i dump it, it shows me NULL if i put this inside the if statement

edit:i have added the return.

<?php
class Ship
{
public $name;
public $strength = 0;

    public function doesGivenShipHaveMoreStrength($givenShip)
    {
         return $givenShip->strength > $this->strength;
    }
}

$myShip = new Ship();
$myShip->name = 'TIE Fighter';
$myShip->strength = 150;

$otherShip = new Ship();
$otherShip->name = 'Imperial Shuttle';
$otherShip->strength = 50;


if ($myShip->doesGivenShipHaveMoreStrength($otherShip)) {

 echo $otherShip->name.' He has more strength';

} else {
    echo $myShip->name.' She has more strength';

}


?>

答

If statements evaluates whatever inside it's braces () . if true or 1 the block or statement will be executed. your function returned a value , and that returned value is later evaluated by the if statement. these are examples that might help you understand how if statements work. the same goes with almost every other programming language.

//example 1
if(true){
    // will be executed
}else{
    // will not executed
}
//example 2
if(false){
    // will not executed
}else{
    // will be executed
}

//example 3
if( 2 > 1){
    // will be executed
}else{
    // will not executed
}
//example 4
if(1){
    // will be executed
}else{
    // will not executed
}
//example 5
if(0){
    // will not executed
}else{
    // will be executed
}
//example 5
if(myFunction()){
    // will be executed
}else{
    // will not executed
}
function myFunction()
{
    return true;
}

答

Your class is not written properly, it should be :

class Ship
{
public $name;
public $strength = 0;

    public function doesGivenShipHaveMoreStrength($givenShip)
    {
          return ($givenShip->strength > $this->strength);
    }
}

Then it will work as expected :) In your version, the function does return nothing, as a result when you use it, it evaluates to NULL, which is equivalent to false, and your test block fails !

答

I would add one more point to the recently answers.

You must add return.
Even you add the return, you shall hit your block containing "He has more strength".

Reason: you are comparing with this->strength which is 0 and your both objects have strength set to 150 & 50 accordingly. It's going to be always true. I would suggest to compare object level values if you are really want to achieve the same functionality.

Revised Answer: You may need to adjust/fix your condition.

as per your code snippet at here

Your value of given ship shall be printed as 50 and current object value is 150 . your function is checking if 50 > 150? answer would be false and you shall hit your else.

Hope this helps

函数和if中的其他PHP

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