Data Types 
integer, float, boolean, string, array, object, resource, NULL | 
  
    Variable Declarations 
$variablename = <value>; 
$anothervariable =& $variablename; (Assign by Reference) | 
  
    Declare Array 
$arrayname = array(); | 
  
    Initialize Array 
$arrayname = array(<value1>, <value2>, <value3>); 
$arrayname = array(<key> => <value>, <key> => <value>); (Define Keys) 
$multiarray = array(<key> => array(<value1>,<value2>)); (Multi-dimensional) | 
  
    Common Array Functions 
sort(<array>); (Sort array assigns new keys) 
asort(<array>); (Sort array maintain keys) 
rsort(<array>); (Sort array in reverse, new keys) 
arsort(<array>); (Sort array in reverse, maintain keys) 
count(<array>); (Count elements) 
count(<array>,COUNT_RECURSIVE); (Count multidimensional array) 
array_push(<array>,<value>); (Push item onto end of array) 
array_pop(<array>); (Pop item off end of array) | 
  
    Comments 
// Comment text 
/* Multi-line comment text */ 
# Comment text | 
  
    Arithmetic Operators 
+ (Addition), - (Subtraction), * (Multiplication), / (Division), % (Modulus) | 
  
    Relational Operators 
== (Equal), === (Equal with type comparison), != (Not equal), <> (Not equal), !== (Not Equal 
with type comparison), < (Less than), > (Greater than), <= (Less than or equal to), >= 
(Greater than or equal to) | 
  
    Logical Operators 
! (logical NOT), && (logical AND), || (logical OR), xor (logical XOR) | 
  
    Assignment Operators 
= (Assign), += (Addition), -= (Subtraction), *= (Multiplication), /= (Division), .= 
(Concatenation), %= (Modulus), &= (And), |= (Or), ^= (Exclusive Or), <<= (Left Shift), >>= 
(Right Shift) | 
  
    String Concatenation 
. (Period) | 
  
    String Manipulation 
substr(<string>,<start>,[<length>]); 
strlen(<string>); 
trim(<string>); 
ltrim(<string>); // Trim left 
rtrim(<string>); // Trim right 
strtolower(<string>); 
strtoupper(<string>); 
str_replace(<search>,<replace>,<string>,[<count>]); 
strpos(<string>, <search>); 
strcmp(<string1>,<string2>); (Binary safe string comparison) 
strcasecmp(<string1>,<string2>); (Binary safe case-insensitive comparison) 
explode(<delim>,<string>,[<limit>]); (Break string into array) 
implode(<delim>,<array>); (Join array into string separated by delim) | 
  
    Cookies 
setcookie (<cookiename>, [<value>],[<expire_time_in_secs_since_epoch>]); 
$_COOKIE['cookiename']; (Returns value of cookie) | 
  
    Sessions 
session_start(); (Create session) 
$_SESSION['key_name'] = value; (Set session variable) 
$variablename = $_SESSION['key_name']; (Retrieve value from session variable) 
session_destroy(); (Destroy session) | 
  
    Error Handling 
try { 
<statements that may cause error>; 
} 
catch (<Exception Class> $exception_name) 
{ 
<statements to execute when error is caught>; 
} | 
  
    Super Globals 
$GLOBALS (Access all global variables in script) 
$_SERVER (Access web server variables) 
$_GET (Values passed to script through URL) 
$_POST (Values passed to script through HTTP Post) 
$_COOKIE (Values passed by user cookie) 
$_FILES (Values passed by HTTP Post File Uploads) 
$_ENV (Values passed to script via the environment) 
$_REQUEST (Values passed by URL, HTTP Post, or user Cookies) 
$_SESSION (Values passed through user's session) | 
  
    If Else 
if (<condition 1>) 
{ <statement 1>; } 
elseif (<condition 2>) 
{ <statement 2>; } 
else 
{ <statement 3>; } | 
  
    Inline If (Ternary) 
<condition> ? true : false; | 
  
    For Loop 
for (<initialize>;<condition>;<update>) 
{ 
<statements>; 
} | 
  
    For Each Loop 
foreach (<array> as [<value> |<key> => <value>]) 
{ 
<statements>; 
[break]; 
[continue]; 
} | 
  
    While Loop 
while (<condition>) 
{ 
<statements>; 
} | 
  
    Do-While Loop 
do 
{ 
<statements>; 
} while (<condition>); | 
  
    Switch 
switch (<expression>) 
{ 
case <literal or type>: 
<statements>; 
[break;] 
case <literal or type>: 
<statements>; 
[break;] 
default: 
<statements>; 
} | 
  
    Function Structure 
function <function_name>([<parameters>]) 
{ 
<statements>; 
[return <value>;] 
} | 
  
    Class Structure 
class <class_name> [<extends base_class>] 
{ 
[var | <modifiers*>] [<class member variables>]; 
[<modifiers*>] function <function_name>([<parameters>]) 
{ 
<statements>; 
} 
} 
* Modifiers <public | pr ivate | static> are implemented in PHP5 | 
  
    Declare and Use Class 
$variable = new class_name(); 
$variable->function_name(); 
class_name::function_name(); (Static call) |