SunshinePHP Developer Conference 2015
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User Contributed Notes 6 notes

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4
niels dot laukens at tijd dot com
9 years ago
For the people that know C: php uses operator short circuit evaluation. That means that as soon as it knows the outcome, it'll stop processing.

<?php
if ( FALSE && some_function() )
    echo
"something";
   
// some_function() will not be called, since the first operand evaluates to false
?>

This comes in handy for situations like this:

<?php
if ( file_exists($filename) && filemtime($filename) > time() )
   
do_something();
   
// filemtime will never give a file-not-found-error, since php will stop evaluating if file_exists returns false
?>
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3
Sinured
7 years ago
As mentioned below, PHP stops evaluating expressions as soon as the result is clear. So a nice shortcut for if-statements is logical AND -- if the left expression is false, then the right expression can’t possibly change the result anymore, so it’s not executed.

<?php
/* defines MYAPP_DIR if not already defined */
if (!defined('MYAPP_DIR')) {
   
define('MYAPP_DIR', dirname(getcwd()));
}

/* the same */
!defined('MYAPP_DIR') && define('MYAPP_DIR', dirname(getcwd()));
?>
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2
Jeffrey
2 years ago
CONTROL STRUCTURE -- BOOLEAN REQUIRED

If you are not sure what will work in your IF statements, try DISECTING your variables. Below I've written three (3) empty CLASS DEFINITIONS (Point, Dimension, and Rectangle), and declared an array called $items that holds all the PHP types you can imagine -- booleans, strings, empty strings, integers, floats, null, arrays, empty arrays, and objects too. The rest of the code really chews up the current $item and spits it out for lunch... Try running this code so you can see the HTML TABLE that is created -- it'll be worth your while.

<?php

class Point { }
class
Dimension { }
class
Rectangle { }

$items = array(true, false, null, 23, 0, -26, 4.21, 0.0, -3.76,
 
'hello', '', array(1, 2, 3), array('', '', ''), array(),
  new
stdClass(), new Point(), new Dimension(), new Rectangle());

echo
'<table cellpadding="4" border="1">
  <tr>
    <th>syntax</th>
    <th>value</th>
    <th>type</th>
    <th>empty</th>
    <th>boolean</th>
  </tr>'
. "\n";

foreach(
$items AS $item)
{
 
$booleanValue = (boolean)$item;
 
$empty = (empty($item) ? 'EMPTY' : '&nbsp;');
 
$type = gettype($item);
 
$syntax = 'if((boolean)';

 
$val;

  if(
$type == boolean)
  {
   
$val = ($booleanValue ? 'true' : 'false');
   
$syntax .= ($val . ')');
  }
  else if(
$type == 'NULL')
  {
   
$val = 'null';
   
$syntax .= 'null)';
  }
  else if(
$type == double && !$booleanValue)
  {
   
$val = '0.0';
   
$syntax .= '0.0)';
  }
  else if(
$type == string)
  {
   
$val = '\'' . $item . '\'';
   
$syntax .= ($val . ')');
  }
  else if(
$type == 'array')
  {
   
$val = $item;
   
$syntax .= '$array)';
  }
  else if(
$type == 'object')
  {
   
$val = get_class($item);
   
$syntax .= ('$' . strtolower($val) . ')');
  }
  else
  {
   
$val = $item;
   
$syntax .= ($val . ')');
  }

  echo
'  <tr style="color: ' . ($booleanValue ? '#006600' : '#880000') . ';">
    <td><code>'
. $syntax . '</code></td>
    <td>'
. $val . '</td>
    <td>'
. $type . '</td>
    <td>'
. $empty . '</td>
    <td>'
. ($booleanValue ? 'TRUE' : 'FALSE') . '</td>
  </tr>'
. "\n";
}

echo
'</table>' . "\n";

?>

Looking at the HTML output: notice that even integers and floats with a value of zero are considered EMPTY, and all that are EMPTY are FALSE boolean values. And take a gander at the boolean type with a false value... somebody is covering there bases!
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1
blackcreeper97
21 hours ago
SUBSCRIBE ME ON YOUTUBE NOW!!!!!
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-9
wintermute
7 years ago
Sinured: You can do the same thing with logical OR; if the first test is true, the second will never be executed.

<?PHP
if (empty($user_id) || in_array($user_id, $banned_list))
{
exit();
}
?>
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-33
asdfasdf@sdaxxxoaosdcom
7 months ago
sadaadslllad ohal ha hasd f wela weñadlfka sdñflas dfñasd asd fwerqw er qwe wqer qwe asdf asdfzxcv dafasdf 3r32 asdf asdf
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