Index

! (negation) operator, Building Complicated Decisions
!= (not equal) operator, Building Complicated Decisions
" " (quotation marks, double)
- debugging, Fixing Parse Errors
- interpolating array elements in double-quoted strings, Modifying Arrays
- string delimiter in PHP, Defining Text Strings
# (octothorpe) character, introducing comments, Comments
$ (dollar sign), denoting variables, PHP in Action
$GLOBALS array, Understanding Variable Scope
- modifying global variable with, Understanding Variable Scope
- recommended use versus global keyword, Understanding Variable Scope
$params array, Simple URL Access with File Functions
$this variable, Object Basics
- example of, Object Basics
$_COOKIE array, Working with Cookies, Working with Cookies
$_GET array, Accessing Form Parameters
$_POST array, Exchanging Information with Users: Making Web Forms, Accessing Form Parameters
$_SERVER array, Exchanging Information with Users: Making Web Forms
- accessing incoming request headers, Serving API Requests
- argv, Writing Command-Line PHP Programs
- HTTPS, Serving API Requests
- HTTP_HOST, Serving API Requests
- PHP_SELF element, Exchanging Information with Users: Making Web Forms
- REQUEST_METHOD element, Exchanging Information with Users: Making Web Forms
- REQUEST_URI, Serving API Requests
- useful elements, Useful Server Variables
$_SESSION array, Storing and Retrieving Information
- removing a key and value from, Login and User Identification
- usernames in, Login and User Identification
% (percent sign)
- beginning format string rules, Formatting text
- literal, matching with LIKE, Retrieving Form Data Safely
- modulus operator, Arithmetic Operators
- Unix shell prompt, Running a PHP REPL
- wildcard character in SQL, Retrieving Form Data Safely
&& (logical and) operator, Building Complicated Decisions
' ' (quotation marks, single)
- debugging, Fixing Parse Errors
- escaping in PHP strings, Defining Text Strings
- string delimiter in PHP, Defining Text Strings
' (apostrophe), in SQL queries, Inserting Form Data Safely
- escaping, Inserting Form Data Safely
() (parentheses)
- following function names, Declaring and Calling Functions
- grouping operations with, Arithmetic Operators, Building Complicated Decisions
* (asterisk)
- ** (exponentiation) operator, Arithmetic Operators
- multiplication operator, Arithmetic Operators
- wildcard character, using with SELECT, Retrieving Data from the Database
+ (plus sign)
- ++ (increment) operator, Operating on Variables
- += (addition and assignment) operator, Operating on Variables, Adding Debug Output
- addition operator, Arithmetic Operators
- (subtraction) operator, Arithmetic Operators
-- (decrement) operator, Operating on Variables
-> (arrow) operator, Object Basics
. (period)
- .. in filenames, Sanitizing Externally Supplied Filenames
- string concatenation operator, Defining Text Strings
. (string concatenation) operator
- combining with assignment operator, Operating on Variables
/ (slash)
- /* and */ delimiting multiline comments, Comments
- // beginning comment lines, PHP in Action, Comments
- division operator, Arithmetic Operators
- in filenames, Sanitizing Externally Supplied Filenames
- path for cookies, Working with Cookies
- using with file access functions, Reading and Writing Parts of Files
:: in static method calls, Object Basics
; (semicolon)
- beginning comments in config files, Environments and Deployment, Modifying PHP Configuration Directives
- ending PHP statements, Whitespace and Case-Sensitivity, Making Decisions, Running a PHP REPL
< (less than) operator, Building Complicated Decisions
<= (less than or equal to) operator, Building Complicated Decisions
<=> (spaceship) operator, Building Complicated Decisions
<?php start tag, Start and End Tags
= (equals) sign
- = (assignment) versus == (comparison), Building Complicated Decisions
- == (equal) operator, Validating strings, Building Complicated Decisions
- === (identity) operator, Numeric or String Elements, Putting Data into the Database, Checking for Errors
- => (array arrrow) operator, Object Basics
- assignment operator, Variables, Operating on Variables
> (greater than) operator, Building Complicated Decisions
>= (greater than or equal to) operator, Building Complicated Decisions
?> PHP end tag, Start and End Tags
?? (null coalesce) operator, Accessing Form Parameters, Isolating What You Test
[] (square brackets)
- accessing an array element, Creating an Array
- bracket matching in editors, Fixing Parse Errors
- creating arrays or adding elements, Creating a Numeric Array
- ending form element names, Accessing Form Parameters
- short array syntax, Creating an Array
  - creating multidimensional arrays, Using Multidimensional Arrays
\ (backslash)
- escape character in PHP, Defining Text Strings
- escaping in PHP strings, Defining Text Strings
- top-level namespace, Namespaces
_ (underscore)
- literal, matching with LIKE, Retrieving Form Data Safely
- wildcard character in SQL, Retrieving Form Data Safely
{} (curly braces)
- bracket matching in editors, Fixing Parse Errors
- enclosing code blocks, Making Decisions, Making Decisions
- enclosing function body, Declaring and Calling Functions
- in message formats, Localizing Output
- interpolating array element values, Modifying Arrays
- multidimensional array value interpolation with, Using Multidimensional Arrays
- variable interpolation with, Putting Variables Inside Strings
|| (logical OR) operator, Building Complicated Decisions

ICU library, Internationalization and Localization
ICU User Guide to Formatting and Parsing, Localizing Output
IDEs (integrated development environments), Fixing Parse Errors
- Xdebug integration with, Scaling Eventually
idle time for sessions, Configuring Sessions
if() construct, PHP in Action
- else clause, Making Decisions
- elseif clauses paired with, Making Decisions
- elseif() with else, Making Decisions
- multiple statements in code block, Making Decisions
- test expression for validating form data, Validating Data
- test expression, evaluating truth value of, Making Decisions
- test expressions, Fixing Parse Errors
- using comparison and logical operators in, Building Complicated Decisions-Building Complicated Decisions
- using function return values in, Returning Values from Functions
implode() function, Modifying Arrays
include directive, Running Code in Another File
include_path configuration directive, Modifying PHP Configuration Directives
initialization expression, Repeating Yourself
ini_get() function, Modifying PHP Configuration Directives
ini_set() function, Configuring Sessions
- changing configuration directives, Modifying PHP Configuration Directives
INSERT command, Putting Data into the Database
- tutorial on, Putting Data into the Database
instanceof operator, Extending an Object
instances, Data and Logic Together: Working with Objects
INT type, Creating a Table
INTEGER type, Creating a Table
integers, Using Different Kinds of Numbers
- checking for, in form data, Numeric or String Elements
- checking range for form data, Number Ranges
integrated development environments (IDEs), Fixing Parse Errors
- Xdebug integration with, Scaling Eventually
interactive shells, Command-Line PHP
- running a PHP REPL, Running a PHP REPL
- running PsySH, Running a PHP REPL
internationalization and localization, Internationalization and Localization
- localizing output, Localizing Output
- manipulating text, Manipulating Text-Manipulating Text
- sorting and comparing text, Sorting and Comparing
intl extension, Internationalization and Localization
in_array() function, Looping Through Arrays
isset() function, Accessing Form Parameters
issue tracking, Issue Tracking
- issue IDs, Issue Tracking
is_readable() function, Inspecting File Permissions
is_writeable() function, Inspecting File Permissions

key/value pairs (array), Array Basics
keywords
- names of, Whitespace and Case-Sensitivity
- whitespace between values and, Whitespace and Case-Sensitivity
krsort() function, Sorting Arrays
ksort() function, Sorting Arrays

namespace keyword, Namespaces
namespaces, Namespaces-Namespaces
- organizing into directories, Source Control
NDB API, Simple URL Access with File Functions
NDB_API_KEY constant, Simple URL Access with File Functions
negation operator (!), Building Complicated Decisions
new operator, Object Basics
- invoking constructors, Constructors
newlines
- fwrite() function and, Reading and Writing Parts of Files
- nl2br() function, Putting It All Together
not equal operator (!=), Building Complicated Decisions
notices, Controlling Where Errors Appear
now documents, Putting Variables Inside Strings
null coalesce operator (??), Accessing Form Parameters, Isolating What You Test
numbers, Numbers
- comparing numbers and strings, Building Complicated Decisions
- locale-specific formatting of, Localizing Output
- using arithmetic operators for math in PHP, Arithmetic Operators
- using different kinds of, Using Different Kinds of Numbers
- validating number ranges for form data, Number Ranges
- validating numeric elements in form data, Numeric or String Elements
number_format() function, PHP in Action
numeric arrays
- creating, Creating a Numeric Array
- iterating through with for(), Looping Through Arrays
- multidimensional, iterating through, Using Multidimensional Arrays
- sorting with sort(), Sorting Arrays
- using foreach() with, Looping Through Arrays

query() method, Retrieving Data from the Database
- chaining fetch() call to, Retrieving Data from the Database
quotation marks
- debugging in PHP-aware editors, Fixing Parse Errors
- debugging string quoting error, Fixing Parse Errors
quote() function, Retrieving Form Data Safely
- correct use with UPDATE, Retrieving Form Data Safely

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Table of Contents for
Learning PHP