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5. Data types
6. Logical expressions
   • Operators
   • Switch statements
7. Loops
8. Functions
9. Error debugging

<?php 
phpinfo();

For including common blocks of DOM in multiple pages

To include relative paths is usually rely on my $rootPath = ''; variable that I declare in a globe file at the root of a project. This file is then included in the first line of all the php files. At the second line I (re)declare the variable, allowing me to specified the repository levels where that file is located. Example $rootPath = '../../';. Then I can use it in the DOM as <?php include_once( '{$basePath}inc/_example.php' ); ?>. Or I can rely on the PHP dirname function to position relatively to the parent repository of that file like <?php include_once( dirname(__FILE__) . '/inc/_example.php' ); ?>.

NOTE: Look for the “dot+equal” .= in the code below.

// original seperated strings as variables
$first_part	= "The quick brown fox";
$last_part	= " jumped over the lazy dog.";

// basic rendering of the variables (without concatenating them)
$first_part . $last_part

// concatenating the 2 variables into one string
$concatenated_parts = $first_part;
$concatenated_parts .= $last_part;
$string = $concatenated_parts;

The above concatenated $string = « The quick brown fox jumped over the lazy dog. »

Note that this level of styling is relevant for backend stuff, NOT frontend where the styling is CSS {text-transform:uppercase;}.

1. Lowercase: echo strtolower($string)        = « the quick brown fox jumped over the lazy dog. »
2. Lowercase: echo strtoupper($string)        = « THE QUICK BROWN FOX JUMPED OVER THE LAZY DOG. »
3. Uppercase first: echo ucfirst($string) = « The quick brown fox jumped over the lazy dog. »
4. Uppercase words: echo ucwords($string) = « The Quick Brown Fox Jumped Over The Lazy Dog. »

$var1 	= true;
$var2 	= false;
$var3 	= null;
$var4 	= '';

Note that $var2 $var3 and $var4 are all 3 negative results has they are NOT TRUE but $var4 differs since it is empty.

• echo is_null($var3); = 1
• echo is_null($var4); = 0
• echo empty($var4); = 1
• echo isset($var4); = 0

$jugg_var1 = '2';			// string
$jugg_var2 = 22;			// integer (int)
$jugg_var3 = 3.14;			// float
$jugg_var4 = array(3,9,27);		// array
$jugg_var5 = true;			// boolean (bool)

Just remember that CONSTANT requires uppercase and are fixed values that you can NOT redefine like a variable can.