if(something) vs if(something===true)

Question

Hi all,

I was doing some self-learning about cakephp (version 1.26).
I got a simple HTML input text field like this:

<input type="text" name="data[testing][name]" id="data[testing][name]">

The value from the Input text box field was checked against the database.
If the value matches the data stored in the database, it will return true.
Here is the code:

{
  $t=$this->data;
  $result=$this->User->findByname($t['testing']['name']); 
  if($result){ //doing something;}
}

I came across a question when I altered the code above with a little change,
but then it failed to work then:

 {
      $t=$this->data;
      $result=$this->User->findByname($t['testing']['name']); 
      if($result===true){ //doing something;}
    }

Could anyone help please?

Answer 1

You are using strict type comparison with === rather than ==, this implies that $result is actually not equal to true there by making the condition fail. Try to see what does come though in the $result variable:

var_dump($result);

Or try this condition with (==):

if($result == true){ //doing something;}

Or simply:

if ($this->User->findByname($t['testing']['name'])){ //doing something;}

Answer 2

That's because $result === true checks, if $result value is true. But your $result variable contains results from the database.

Answer 3

Assuming here that findByName returns some kind of object or array. if you use if ($result) this object/array will be cast to a boolean.

If however you use if ($result === true) you're strictly comparing an object/array to the boolean true, this comparison will always evaluate to false.

Answer 4

The PHP reference has a very nice explanation of how type comparison is done. The quick answer is that you are now doing a much stricter comparison, and some edge cases are falling through the cracks. You will probably be fine with $result == true

http://php.net/manual/en/language.operators.comparison.php

Answer 5

Coarsely, the if operator casts your argument into a boolean and evaluates it. So if($result) converts $result into true or false. On the other hand, === actually checks for both type and "value" equality, so true === $val will only return true if $val is the boolean true. === obviously returns a boolean, so no casting is necessary for the subsequent evaluation within if. What this means for you is that if($result) processes the block if $result casts into true. Examples of things that become true are 1, '1', and new Object(). Conversely, if($result===true) doesn't immediately cast $result. It checks it in type and "value" against boolean true.

If $result is, say 1, the former control structure will process the block, but the latter won't.

Answer 6

=== means equal AND the same type of what you equaling to... but $result contains data from db..so it's not Boolean... use == instead:

if($result==true)

Answer 7

In your code, when there is a result, the return is non-zero, therefore it will evaluate to true.

=== is the identity operator and will return true when the two objects are identical

e.g. 1===1 (true) true===true (true) true===1 (false)

== is the equality operator and will return true when the two objects are equal or equivalent.

e.g. 1==1 (true) true==true (true) true==1 (true)

findByName will return an array or unset. unset will equate to false and an array will equate to true.

the value true itself is never returned in your code, so === will never be true.