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PHP Examples

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PHP Syntax

Write text to the output using PHP Keywords, classes, functions, and user-defined functions ARE NOT case-sensitive Variable names ARE case-sensitive

Syntax explained

PHP Comments

Syntax for single-line comments Syntax for multi-line comments Using comments to leave out parts of the code

Comments explained

PHP Variables

Create different variables Test global scope (variable outside function) Test local scope (variable inside function) Use the global keyword to access a global variable from within a function Use the $GLOBALS[] array to access a global variable from within a function Use the static keyword to let a local variable not be deleted after execution of function

Variables explained

PHP Echo and Print

Display strings with the echo command Display strings and variables with the echo command Display strings with the print command Display strings and variables with the print command

Echo and Print explained

PHP Data Types

PHP string PHP integer PHP float PHP array PHP object PHP NULL value

Data Types explained

PHP Strings

Get the length of a string - strlen() Count the number of words in a string - str_word_count() Reverse a string - strrev() Search for a specific text within a string - strpos() Replace text within a string - str_replace()

Strings explained

PHP Numbers

Check if the type of a variable is integer Check if the type of a variable is float Check if a numeric value is finite or infinite Invalid calculation will return a NaN value Check if a variable is numeric Cast float and string to integer

Numbers explained

PHP Math

Find the value of PI Find the lowest and highest value in a list of arguments Find the absolute (positive) value of a number Find the square root of a number Round a floating-point number to its nearest integer Generate a random number Generate a random number between 10 and 100

PHP Constants

Case-sensitive constant name Case-insensitive constant name Create a Array constant with define() Use a constant inside a function (when it is defined outside the function)

Constants explained

PHP Operators

Arithmetic operator: Addition (+) Arithmetic operator: Subtraction (-) Arithmetic operator: Multiplication (*) Arithmetic operator: Division (/) Arithmetic operator: Modulus (%) Assignment operator: x = y Assignment operator: x += y Assignment operator: x -= y Assignment operator: x *= y Assignment operator: x /= y Assignment operator: x %= y Comparison operator: Equal (==) Comparison operator: Identical (===) Comparison operator: Not equal (!=) Comparison operator: Not equal (<>) Comparison operator: Not identical (!==) Comparison operator: Greater than (>) Comparison operator: Less than (<) Comparison operator: Greater than or equal (>=) Comparison operator: Less than or equal (<=) Comparison operator: Spaceship (<=>) Increment operator: ++$x Increment operator: $x++ Decrement operator: --$x Decrement operator: $x-- Logical operator: and Logical operator: or Logical operator: xor Logical operator: && (and) Logical operator: || (or) Logical operator: not String operator: Concatenation of $txt1 and $txt2 String operator: Appends $txt2 to $txt1 Array operator: Union (+) Array operator: Equality (==) Array operator: Identity (===) Array operator: Inequality (!=) Array operator: Inequality (<>) Array operator: Non-identity (!==) Conditional assignment operator: Ternary (?:) Conditional assignment: Null coalescing (??)

Operators explained

PHP If...Else and Switch Statements

The if statement The if...else statement The if...elseif...else statement The switch statement

Conditions explained

PHP While and For Loops

The while loop The do...while loop Another do...while loop The for loop The foreach loop The break statement in a loop The continue statement in a loop

Loops explained

PHP Functions

Create a function Function with one argument Function with two arguments Function with default argument value Function that returns a value Return type declarations Passing arguments by reference

Functions explained

PHP Arrays

Indexed arrays count() - Return the length of an array Loop through an indexed array Associative arrays Loop through an associative array

Arrays explained

PHP Multidimensional Arrays

Output elements from a multidimensional array Loop through a multidimensional array

Multidimensional Arrays explained

PHP Sorting Arrays

sort() - Sort array in ascending alphabetical order sort() - Sort array in ascending numerical order rsort() - Sort array in descending alphabetical order rsort() - Sort array in descending numerical order asort() - Sort array in ascending order, according to value ksort() - Sort array in ascending order, according to key arsort() - Sort array in descending order, according to value krsort() - Sort array in descending order, according to key

Sorting Arrays explained

PHP Superglobals

$GLOBAL - Used to access global variables from anywhere in the PHP script $_SERVER - Holds information about headers, paths, and script locations $_REQUEST - Used to collect data after submitting an HTML form $_POST - Used to collect form data after submitting an HTML form. Also used to pass variables $_GET - Collect data sent in the URL

Superglobals explained

PHP Regular Expressions

Do a case-insensitive search for "w3schools" in a string Do a case-insensitive count of the number of occurrences of "ain" in a string Replace "Microsoft" with "W3Schools" in a string

Regular Expressions explained

PHP Form Validation

PHP Form Validation

Form Validation explained

PHP Date and Time

Format today's date in several ways Automatically update the copyright year on your website Output the current time (server time) Set timezone, then output current time Create a date and time from a number of parameters in mktime() Create a date and time from the strtotime() function Create more dates/times from strtotime() Output the dates for the next six Saturdays Output the number of days until 4th of July

Date and Time explained

PHP Include Files

Use include to include "footer.php" in a page Use include to include "menu.php" in a page Use include to include "vars.php" in a page Use include to include a non-existing file Use require to include a non-existing file

Include Files explained

PHP File Handling

Use readfile() to read a file and write it to the output buffer

File Handling explained

PHP File Open/Read/Close

Use fopen(), fread(), and fclose() to open, read, and close a file Use fgets() to read a single line from a file Use feof() to read through a file, line by line, until end-of-file is reached Use fgetc() to read a single character from a file

File Open/Read/Close explained

PHP Cookies

Create and retrieve a cookie Modify a cookie value Delete a cookie Check if cookies are enabled

Cookies explained

PHP Sessions

Start a session Get session variable values Get all session variable values Modify a session variable Destroy a session

Sessions explained

PHP Filters

Use filter_list() to list what the PHP filter extension offers Sanitize a string Validate an integer Validate an integer that is 0 Validate an IP address Sanitize and validate an email address Sanitize and validate a URL

Filters explained

PHP JSON

Encode an associative array into a JSON object Decode JSON data into a PHP object Access the values from a PHP object Loop through the values of a PHP object

PHP JSON explained

PHP Exceptions

Throw an Exception Use try..catch to show a message when an exception is thrown Use finally Output information about an exception that was thrown

PHP Exceptions explained

PHP Classes/Objects

Define a class and an object Using the $this keyword Using the instanceof keyword Creating a constructor Creating a destructor Inheritance Class constants Abstract classes Traits Static method Static property

PHP OOP (Classes/Objects) explained

PHP Select Data From MySQL

Select data with MySQLi (Object-oriented) Select data with MySQLi (Procedural) Put the resut in an HTML table (Object-oriented) Select data with PDO (+ Prepared statements)

Select Data From MySQL explained

PHP SimpleXML Parser

Use simplexml_load_string() to read XML data from a string Use simplexml_load_file() to read XML data from a file Get node values Get node values of specific elements Get node values - loop Get attribute values Get attribute values - loop

SimpleXML Parser explained

PHP XML Expat Parser

Initialize an XML Expat parser, define some handlers, then parse an XML file

XML Expat Parser explained

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