PHP printed boolean value is empty, why?

php boolean echo
Jérôme Verstrynge picture Jérôme Verstrynge · Jan 28, 2012 · Viewed 27.1k times · Source

I am new to PHP. I am implementing a script and I am puzzled by the following:

$local_rate_filename = $_SERVER['DOCUMENT_ROOT']."/ghjr324l.txt";
$local_rates_file_exists = file_exists($local_rate_filename);

echo $local_rates_file_exists."<br>";

This piece of code displays an empty string, rather than 0 or 1 (or true or false). Why? Documentation seems to indicate that a boolean value is always 0 or 1. What is the logic behind this?

Answer

dynamic picture dynamic · Jan 28, 2012

Be careful when you convert back and forth with boolean, the manual says:

A boolean TRUE value is converted to the string "1". Boolean FALSE is converted to "" (the empty string). This allows conversion back and forth between boolean and string values.

So you need to do a:

echo (int)$local_rates_file_exists."<br>";

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