return boolean anomaly

[shaunmckinnon]

Hello:

 

I've just started learning OOPHP, and I love it!!! However, I've come across a strange issue.

I'm trying to return a boolean value from my ternary statement. It will not return the boolean. I can return a string literal, an integer, anything else you can think of, but not a boolean.

 

I'm curious if someone could explain why. Here's the code:

// delete the row required
			$sql = "DELETE FROM $table WHERE id = $id";
			if($conn -> query($sql)) {
				try {
					$num = ($conn -> affected_rows > 0) ? true : false;
					return $num;
				} catch (Exception $e) {
					echo '<br>Caught exception: ', $e -> getMessage(), '<br>';
				}
			} else {
				return false;
			}

Any help is appreciated. Thank you so much in advance.

[akphidelt2007]

Well I don't know the correct terminology but just from experience, false is no value. So if it returns false, it returns an empty value. Return true returns 1. So depending on how you are checking for this "return" you might not be using it the correct way.

[kicken]

what makes you think you can't return a boolean? Also, there's no need for the ternary operator there, you can just do: return $conn->affected_rows > 0;

Edited September 5, 2013 by kicken

[shaunmckinnon]

Well I don't know the correct terminology but just from experience, false is no value. So if it returns false, it returns an empty value. Return true returns 1. So depending on how you are checking for this "return" you might not be using it the correct way.

False should return as "0", as True returns as "1". Either way, it doesn't return.

 

 

what makes you think you can't return a boolean? Also, there's no need for the ternary operator there, you can just do: return $conn->affected_rows > 0;

Thanks for the help on getting rid of the ternary. I've tried a crazy amount of things and now I'm stuck in a circle of bad practice. lol

 

However, even with your change, it still won't return the boolean. I still get nothing. Here is the current code:

			$sql = "DELETE FROM $table WHERE id = $id";
			if($conn -> query($sql)) {
				try {
					return $conn -> affected_rows > 0;
				} catch (Exception $e) {
					echo '<br>Caught exception: ', $e -> getMessage(), '<br>';
				}
			} else {
				return false;
			}

[shaunmckinnon]

I don't know if this makes a difference, but here is the whole method:

public function deleteIt($id)
		{
			$conn = $this -> connect_open();

			// set the table
			$table = $this -> table;

			// delete the row required
			$sql = "DELETE FROM $table WHERE id = $id";
			if($conn -> query($sql)) {
				try {
					return $conn -> affected_rows > 0;
				} catch (Exception $e) {
					echo '<br>Caught exception: ', $e -> getMessage(), '<br>';
				}
			} else {
				return false;
			}

			$conn = $this -> connect_close();
		}

[akphidelt2007]

 

False should return as "0", as True returns as "1". Either way, it doesn't return.

 

 

False can be used as 0, but it does not return 0. It returns an empty string. You can use (int) false to get the zero.

[kicken]

False should return as "0", as True returns as "1". Either way, it doesn't return.

No, false returns as false, and true returns as true. If you're talking about what they would be after converting them to a string (such as by echo'ing them) then false become "" (empty string) and true becomes "1". If you want to see exactly what a value is (type and contents) use var_dump($var);

[.josh]

what are you doing to compare the returned value

[shaunmckinnon]

False can be used as 0, but it does not return 0. It returns an empty string. You can use (int) false to get the zero.

Thank you. I never knew that, but it makes perfect sense.

 

 

what are you doing to compare the returned value

I'm not doing anything yet. I just want a returned value of either true or false. It's so bizarre. I could just return 1 or 0 and It works. But the second I change it to true or false, even with (int)false, it refuses to obey.

Here is the adjusted code:

public function deleteIt($id)
		{
			$conn = $this -> connect_open();

			// set the table
			$table = $this -> table;

			// delete the row required
			$sql = "DELETE FROM $table WHERE id = $id";
			if($conn -> query($sql)) {
				try {
					return (int)$conn -> affected_rows > 0;
				} catch (Exception $e) {
					echo '<br>Caught exception: ', $e -> getMessage(), '<br>';
				}
			} else {
				return (int)false;
			}

			$conn = $this -> connect_close();
		}

[.josh]

well how do you know what you are(n't) getting unless you're looking at it somehow?

[0xMatt]

return $conn -> affected_rows > 0;
 

Will always return false.

return ($conn->affected_rows > 0) ? true : false;

is what you want.

 

Edit:

 

Yeah, I had messed up my return statement which threw me off as well.

Edited September 5, 2013 by 0xMatt

[shaunmckinnon]

Never mind. I var_dump'd the value in my file that's getting the returned value and it comes up bool(false).

$dbman = new DBManipulate;
	$dbman -> set_Table('users');
	$result = $dbman -> deleteIt(6);
	var_dump($result);

I need to learn more. Cheers and thanks for the help!

[akphidelt2007]

return $conn -> affected_rows > 0;

 

Will always return false.

return ($conn->affected_rows > 0) ? true : false;

is what you want.

 

That's not true. It will return true or false

[shaunmckinnon]

return $conn -> affected_rows > 0;

 

Will always return false.

return ($conn->affected_rows > 0) ? true : false;

is what you want.

Thanks!!! That is exactly what I want. My brain is fried. I've been doing this for 12 hours straight. Time to unplug.

[shaunmckinnon]

Fixed with this:

		public function deleteIt($id)
		{
			$conn = $this -> connect_open();

			// set the table
			$table = $this -> table;

			// delete the row required
			$sql = "DELETE FROM $table WHERE id = $id";
			if($conn -> query($sql)) {
				try {
					return (int)(($conn->affected_rows > 0) ? true : false);
				} catch (Exception $e) {
					echo '<br>Caught exception: ', $e -> getMessage(), '<br>';
				}
			} else {
				return (int)false;
			}

			$conn = $this -> connect_close();
		}

Thanks again for the help.

[akphidelt2007]

Thanks!!! That is exactly what I want. My brain is fried. I've been doing this for 12 hours straight. Time to unplug.

 

These statements are equivalent...

 

 

return ($conn->affected_rows > 0) ? true : false;
 
return $conn->affected_rows > 0;

[akphidelt2007]

Fixed with this:

		public function deleteIt($id)
		{
			$conn = $this -> connect_open();

			// set the table
			$table = $this -> table;

			// delete the row required
			$sql = "DELETE FROM $table WHERE id = $id";
			if($conn -> query($sql)) {
				try {
					return (int)(($conn->affected_rows > 0) ? true : false);
				} catch (Exception $e) {
					echo '<br>Caught exception: ', $e -> getMessage(), '<br>';
				}
			} else {
				return (int)false;
			}

			$conn = $this -> connect_close();
		}

Thanks again for the help.

 

There's no reason to return a boolean if you want a value. When I need to get 1s and 0s, I do...

 

 

return $conn->affected_rows > 0 ? 1 : 0;

[AbraCadaver]

That's not the best answer, it's sloppy and strange, and well kinda dumb!  I think you need to decide what you want and why.  Most people want true or false, just because you can't echo it doesn't mean you need inegers.

return (int)(($conn->affected_rows > 0) ? true : false);
//same as
return (int)($conn->affected_rows > 0);
//same as
return ($conn->affected_rows > 0) ? 1 : 0;

For that matter boolean:

return (bool)$conn->affected_rows;

Or hell, just this if you do a loose test (it's either 0 or not):

return $conn->affected_rows;

Edited September 5, 2013 by AbraCadaver

[.josh]

would also like to point out that true will only equate to 1 and false will only equate to 0 or '' if they are loosely compared. If you strictly compare them then they do not equate.

 

For example:

 

if (true == 1)    echo "true == 1    "; // this will echo
if (true === 1)   echo "true === 1   "; // this will not echo
if (false == 0)   echo "false == 0   "; // this will echo
if (false === 0)  echo "false === 0  "; // this will not echo
if (false == '')  echo "false == ''  "; // this will echo
if (false === '') echo "false === '' "; // this will not echo