PHP tags (standard, echo, short).
Single line comments; multi-line comments
Write data to the script’s output: echo vs print();
Script termination.
Constants. Possible ways to define. Possible values that they contain. Magic constants
Variables (naming, case-sensitivity)
Arithmetic operators ($a**2 etc)
Assignment operators ($a = 1 vs $a += 1, $a = $b vs $a = &$b etc)
Comparison Operators ($a == $b, $a === $b etc); Comparing of float values with epsilon technique
Incrementing/Decrementing Operators (echo $a++ vs echo ++$a)
Logical Operators ($a && $b, $a || $b, !$a etc.)
String operators (concatenation and concatenating assignment)
Debug functions (var_dump(), var_export(), print_r())
if, while, for, foreach, switch and their alternative syntax
continue and break statements
Global and functional scope
Single quotes vs Double quotes
Using printf() for formatting
Enumerative and associative
Short array syntax
Iteration of an array by using foreach
HTTP request: HTTP method, URI, headers and request body
HTTP response: status code,headers and content
Web-Form submit
Data format inside request body
$_GET, $_POST, $_REQUEST
$_FILES
Сookies and sessions in php
Data types: 4 scalar types, 4 compound types, 2 special types. Pseudo-types
Type Casting (with casting operators and functions). Detecting Types
Array Operators ($arr + $arrB, $arr == $arrB etc.)
Type Operators (instanceof)
'Fall through' in switch statement
Ternary Operators
require vs include
Arguments by reference
Strings as Arrays
Search & replace
Working with arrays as a stack and as a queue: array_push(), array_pop(), array_shift(), array_unshift()
Validate (in_array(), array_key_exists() etc)
Sort and shuffle arrays
Class vs object
Inheritance
Class methods and properties visibility. Default visibility
Variable variables
Operator precedence
Error Control operator
Type-hinting in functions
Return type declaration
Heredoc and Nowdoc Syntax
‘Filter input Escape output’ rule
ctype_* functions, filter_var()
HTTPS concept
Cross-site scripting (XSS)
Cross-Site Request Forgeries
SQL injection attacks prevention
phpdoc (@param, @return, @var etc)
Working with filesystem with C-style functions (open/create, read, write, and close a file handle, working with folders)