PHP. The Basics

1. Comparison operators

<?php
$a = 5;   // 5 as an integer

var_dump($a == 5);       // compare value; return true
var_dump($a == '5');     // compare value (ignore type); return true
var_dump($a === 5);      // compare type/value (integer vs. integer); return true
var_dump($a === '5');    // compare type/value (integer vs. string); return false

//Equality comparisons
if (strpos('testing', 'test')) {    // 'test' is found at position 0, which is interpreted as the boolean 'false'
    // code...
}

// vs. strict comparisons
if (strpos('testing', 'test') !== false) {    // true, as strict comparison was made (0 !== false)
    // code...
}

3. Case

<?php
$answer = test(2);    // the code from both 'case 2' and 'case 3' will be implemented

function test($a)
{
    switch ($a) {
        case 1:
            // code...
            break;             // break is used to end the switch statement
        case 2:
            // code...         // with no break, comparison will continue to 'case 3'
        case 3:
            // code...
            return $result;    // within a function, 'return' will end the function
        default:
            // code...
            return $error;
    }
}

4. Global namespace

When using namespaces, you may find that internal functions are hidden by functions you wrote. 
To fix this, refer to the global function by using a backslash before the function name.

<?php
namespace phptherightway;

function fopen()
{
    $file = \fopen();    // Our function name is the same as an internal function.
                         // Execute the function from the global space by adding '\'.
}

function array()
{
    $iterator = new \ArrayIterator();    // ArrayIterator is an internal class. Using its name without a backslash
                                         // will attempt to resolve it within your namespace.
}


5. Concatenation

<?php
$a  = 'Multi-line example';    // concatenating assignment operator (.=)
$a .= "\n";
$a .= 'of what not to do';

// vs

$a = 'Multi-line example'      // concatenation operator (.)
    . "\n"                     // indenting new lines
    . 'of what to do';
    
    
6. Variable declarations

At times, coders attempt to make their code “cleaner” by declaring predefined variables 
with a different name. What this does in reality is to double the memory consumption of said script. 
For the example below, let us say an example string of text contains 1MB worth of data, 
by copying the variable you’ve increased the scripts execution to 2MB.

<?php
$about = 'A very long string of text';    // uses 2MB memory
echo $about;

// vs

echo 'A very long string of text';        // uses 1MB memory


7. Ternary operators

<?php
$a = 5;
echo ($a == 5) ? return true : return false;    // this example will output an error

// vs

$a = 5;
return ($a == 5) ? 'yay' : 'nope';    // this example will return 'yay'

8. Newdoc

$str = <<<'EOD'             // initialized by <<<
Example of string
spanning multiple lines
using nowdoc syntax.
$a does not parse.
EOD;                        // closing 'EOD' must be on it's own line, and to the left most point

<?php
return ($a == 3 && $b == 4) && $c == 5;

9. HereDoc

<?php
$a = 'Variables';

$str = <<<EOD               // initialized by <<<
Example of string
spanning multiple lines
using heredoc syntax.
$a are parsed.
EOD;                        // closing 'EOD' must be on it's own line, and to the left most point

/**
 * Output:
 *
 * Example of string
 * spanning multiple lines
 * using heredoc syntax.
 * Variables are parsed.
 */