General Types

Comments

<?php
// C++ line Comment

/*
C-style comment block
*/

# Shell Style Comment
?>

Case Sensitivity

• Variables - are Case sensitive

  <?php
  $caseSensitive = "I am unique.";
  $CaseSensitive = "I’m different.";
  echo $caseSensitive;
  echo $CaseSensitive;
  ?>
  

• Classes - are not case sensitive

  <?php
  class Company {
  // …
  }
  $c1 = new ComPanY;
  $c2 = new COMPANY;
  ?>
  

• Functions - are not case sensitive

  <?php
  function companyName() {
  // …
  }
  companyname();
  CompanyName();
  COMPANYNAME();
  ?>
  

Integers

<?php
$regInt = 1234;
$octNum = 01234;
$hexNum = 0xABC;
$binaryNum = 0b1000;

var_dump($regInt);
var_dump($octNum);
var_dump($hexNum);
var_dump($binaryNum);
//output: int(1234) int(668) int(2748) int(8)
?>

Floats

<?php
$flaot = 1.234;
$scientific = 0.1234E4;
$scientific2 = 1234E-4;
var_dump($flaot);
var_dump($scientific);
var_dump($scientific2);
//output: float(1.234) float(1234) float(0.1234)
?>

Note

• Scientific notation can be used like e
• If a second variable is declared with the same name the first will be overriden

Booleans

<?php
$bool = false;
$intHasValue = 1;
$intNoValue = 0;
$StringHasValue = "abc";
$StringNoValue = "";

var_dump($bool);
var_dump((bool)$intHasValue);
var_dump((bool)$intNoValue);
var_dump((bool)$StringHasValue);
var_dump((bool)$StringNoValue);
//output: bool(false) bool(true) bool(false) bool(true) bool(false)
?>

Note

putting (bool) in front of variables will check if empty or not

Constant

<?php
define('NEW_CONSTANT', "Hello new constant ");

echo NEW_CONSTANT;
var_dump(NEW_CONSTANT);
//output: Hello new constant string(19) "Hello new constant "
?>

Note

• Constant naming convention in php is having the name of the constant all caps and seperating the words by underscore
• parameters are define(‘name’, value);
• Constants can be access by other functions or classes (Glopal variables)

Determine Type

<?php
define('CHECK_CONSTANT', "Yes, I am a constant!");

$intVar = 1234;
$stringVar = "I'm a String";
$boolVar = true;
$floatVar = 12.34;

echo is_int($intVar);
echo is_string($stringVar);
echo is_bool($boolVar);
echo is_float($floatVar);

echo defined('CHECK_CONSTANT');
?>

Note

If the variable exist these functions will returen 1 otherwise they will return nothing