PHP Question: Printing A Boolean Value

8th April 2011 - 2 minutes read time

Question

What will the following code print, and why?

echo TRUE;









 

Answer

The answer here is "1" because when we print out a boolean value in this way it is cast into a string, resulting in the integer value 1. If you try to do the same thing with a false value you will get no output (an empty string). This is important to remember as some items are lost in translation when printing out debug messages, even when using print_r().

The correct way to print out a boolean value is to use the var_dump() function. This will print out the correct value as well telling you what data type this is.

var_dump(TRUE); // bool(true)

You can also use an if statement to print out the value in the correct way.

$value = TRUE;
if ($value === TRUE) {
   echo 'The value is TRUE';
} else {
   echo 'The value is FALSE';
}

You can also print out TRUE as 1 and FALSE as 0, which is useful when inserting the value into a database. To do this you can use the sprintf() function to cast the boolean value into an integer.

print sprintf("%b", FALSE); // prints 0
print sprintf("%b", TRUE); // prints 1
print
PHP

Comments

I am not answering it because it will mean I am showing off!

Submitted by Anonymous on Sat, 04/09/2011 - 01:41

Permalink

42!

Submitted by Anonymous on Sat, 04/09/2011 - 08:35

Permalink

It prints 1. But the true problem comes with <code>echo FALSE</code> witch will print out nothing instead of 0 (zero). I've had some hassle with such code some time ago... :)

Submitted by Mihai Baboi on Sat, 04/09/2011 - 15:35

Permalink

Add new comment

The content of this field is kept private and will not be shown publicly.
CAPTCHA
3 + 11 =
Solve this simple math problem and enter the result. E.g. for 1+3, enter 4.
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.

Related Content

Generating Colour Palettes From Images In PHP

4th August 2024

A common web design pattern is to incorporate an image into the design of the page. This creates a tighter integration with the image and the rest of the page.

The main issue in designing a page around the image is that the colours of the page must match the image. Otherwise this creates a dissonance between the image and the styles of the site.

Read more

Validating XML Files With XML Schema Definitions In PHP

21st July 2024

XML is a useful format for configuration, data storage, and transmitting data from one system to another. As a human readable format that can be easily read by machines it quickly gained favor in lots of different systems as a mechanism for data storage.

Read more

Approximating Pi Using A Circle And A Square

26th May 2024

Pi day was a few weeks ago, but I came across this simple approximation of pi recently and decided to put together an example in PHP since it seemed pretty simple.

This approximation of pi centers around a real world example, but we can simulate this using some code.

Read more

Drawing A Parabolic Curve With Straight Lines In PHP

12th May 2024

A parabolic curve is a type of curve where every point is an equal distance from a focal point. There a number of different way to generate this sort of curve using math, but one of the simplest is to use straight lines to create the illusion of the curve.

Read more

Recreating Spotify Wrapped In PHP

17th March 2024

I quite like the end of the year report from Spotify that they call "Wrapped". This is a little application in which they tell you what your favorite artist was and what sort of genres you listened to the most during the year.

Read more