PHP Cheatsheet (original) (raw)

**PHP stands for the Hypertext Preprocessor. It is a popular, open-source server-side scripting language designed for web development but also used as a general-purpose programming language. It is widely used to create dynamic web pages and can be embedded into HTML. PHP code is executed on the server, generating HTML that is then sent to the client.

This article provides an in-depth PHP Cheat Sheet, a must-have for every web developer.

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PHP Cheatsheet

**What is a PHP Cheatsheet?

A PHP Cheatsheet is a quick reference guide that shows the most important PHP commands, syntax, and examples all in one place. It helps programmers remember how to write PHP code easily without searching through long documents.

It’s like a summary of the basic and useful PHP things you need to know.

PHP Features

Here are some of the main features of PHP:

1. Basic Syntax

PHP scripts start with <?php and end with ?>.

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2. Variables and Constants

Variables store data values. A variable starts with a $ sign followed by the name. PHP variables are dynamically typed, meaning you don’t need to declare their type.

Variable Description
$name = "PHP"; String value
$age = 25; Integer value
$price = 9.99; Float (decimal number)
$is_active = true; Boolean (true or false)

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Constants

Constants in PHP are fixed values that do not change during script execution. They are defined using define() or const. They are globally accessible and do not begin with $.

Feature Description
define() Defines a constant
const keyword Alternative way to define constants (PHP 5.3+)
Case-sensitivity Constants are case-sensitive by default
Global scope Constants are accessible anywhere after declaration
No $ symbol Constants are written without a dollar sign

3. Magic Constants

Magic constants in PHP are built-in constants that change based on context, like file name, line number, or function name.

Magic Constant Description
__LINE__ Current line number of the file
__FILE__ Full path and filename of the file
__DIR__ Directory of the file
__FUNCTION__ Name of the current function
__CLASS__ Name of the current class
__TRAIT__ Name of the current trait
__METHOD__ Name of the current method
__NAMESPACE__ Name of the current namespace
ClassName::class It gives the complete name of the class, including its namespace, as a text value (string).

4. Data Types

PHP supports several data types used to store different kinds of values:

Type Description Example
**String Text data enclosed in quotes $name = "Anjali";
**Integer Whole numbers $count = 10;
**Float Decimal numbers (also called double) $price = 15.75;
**Boolean True or False $is_valid = true;
**Array Collection of values stored in a single variable $colors = ["red", "blue"];
**Object Instance of a class with properties and methods $car = new Car();
**NULL Represents a variable with no value assigned $empty = null;
**Resource Special variable that holds a reference to external resources like database connections or files $handle = fopen("file.txt", "r");

5. Operators

PHP operators perform operations on variables and values.

Operator Type Description Examples
Arithmetic +, -, *, /, % $sum = 5 + 3;
Assignment =, +=, -=, *=, /= $a += 2;
Comparison ==, ===, !=, !==, <, > a==a == a==b;
Logical &&, `
Increment/Decrement ++, -- $count++;

PHP `

a+a + a+b . "\n"; // 8 $a++; echo $a; // 6 ?>

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6. Loops

PHP Loops are a useful feature in most programming languages. With loops you can evaluate a set of instructions/functions repeatedly until certain condition is reached.

Loop Type Description Syntax Example
**for Repeats a block of code a specific number of times for (initialization; condition; increment) { }
**while Executes code repeatedly while the condition is true (checks condition first) while (condition) { }
**do-while Executes code once, then repeats while the condition is true do { } while (condition);
**foreach Iterates over each element in an array or collection foreach ($array as $value) { }

PHP `

i<=3;i <= 3; i<=3;i++) { echo "Value of i: $i\n"; } echo "\n"; // While Loop echo "While Loop:\n"; $j = 1; while ($j <= 3) { echo "Value of j: $j\n"; $j++; } echo "\n"; // Do-While Loop echo "Do-While Loop:\n"; $k = 4; do { echo "Value of k: $k\n"; $k++; } while ($k < 4); echo "\n"; // Foreach Loop echo "Foreach Loop:\n"; $colors = ["Red", "Green", "Blue"]; foreach ($colors as $color) { echo "Color: $color\n"; } ?>

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Output

For Loop: Value of i: 1 Value of i: 2 Value of i: 3

While Loop: Value of j: 1 Value of j: 2 Value of j: 3

Do-While Loop: Value of k: 4

Foreach Loop: Color: Red Color: Green Color: Blue

7. Conditional Statements

Conditional Statements is used in PHP to execute a block of codes conditionally. These are used to set conditions for your code block to run. If certain condition is satisfied certain code block is executed otherwise else code block is executed.

Statement Type Description Syntax Example
**if-else Runs code if a condition is true; otherwise runs the else block if (condition) { } else { }
**elseif Allows checking multiple conditions sequentially if (condition) { } elseif (condition) { } else { }
**switch Selects one block of code to execute from many options switch (variable) { case value: ... break; default: ... }

PHP `

18) { echo "You are an adult.\n"; } echo "\n"; // If-Else statement $score = 40; echo "If-Else Statement:\n"; if ($score >= 50) { echo "You passed.\n"; } else { echo "You failed.\n"; } echo "\n"; // If-Elseif-Else statement $marks = 75; echo "If-Elseif-Else Statement:\n"; if ($marks >= 90) { echo "Grade: A\n"; } elseif ($marks >= 75) { echo "Grade: B\n"; } elseif ($marks >= 50) { echo "Grade: C\n"; } else { echo "Grade: F\n"; } echo "\n"; // Switch statement $day = "Monday"; echo "Switch Statement:\n"; switch ($day) { case "Monday": echo "Start of the week.\n"; break; case "Friday": echo "Almost weekend.\n"; break; case "Sunday": echo "Rest day.\n"; break; default: echo "Just another day.\n"; } ?>

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Output

If Statement: You are an adult.

If-Else Statement: You failed.

If-Elseif-Else Statement: Grade: B

Switch Statement: Start of the week.

8. Date and Time

PHP Date and time provides powerful built-in functions and classes to work with dates and times. The main ways to handle dates are using the date() function and the DateTime class.

Common Date and Time Formats

Format Description Example Output
Y 4-digit year 1996
m 2-digit month (01 to 12) 10
d 2-digit day (01 to 31) 13
H Hour in 24-hour format (00-23) 05
i Minutes (00-59) 35
s Seconds (00-59) 32
D Day of week (Mon, Tue, etc.) Sun
N ISO-8601 numeric day of week (1 = Monday) 7

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Output

2025-05-24 09:28:55

DateTime Methods

Method Description
format() Formats the date/time as a string
getTimestamp() Returns the Unix timestamp
modify() Alters the date/time by adding or subtracting time
setDate() Sets the date (year, month, day)
setTime() Sets the time (hour, minute, second)

9. Strings

Strings are sequences of characters used to store and manipulate text. PHP provides many built-in functions to work with strings, including concatenation, searching, replacing, slicing, and changing case.

Function Description
strlen() Returns length of a string
strrev() Reverses a string
strtoupper() Converts string to uppercase
strtolower() Converts string to lowercase
strpos() Finds position of a substring
str_replace() Replaces text within a string
substr() Extracts part of a string
trim() Trim spaces from both ends
explode() Splits string into an array
implode() Joins array elements into a string
. (concatenation) Joins two or more strings

PHP `

gfg.gfg . gfg.geeks . "\n"; // Find position of substring echo strpos($geeks, "for") . "\n"; // Replace text echo str_replace("FG", "fg", $gfg) . "\n"; // Extract substring echo substr($geeks, 6, 3) . "\n"; // Convert to uppercase echo strtoupper($geeks) . "\n"; // Split string into array and print print_r(explode("-", $geeks)); ?>

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Output

GFG stands-for-GeeksforGeeks 7 Gfg -fo STANDS-FOR-GEEKSFORGEEKS Array ( [0] => stands [1] => for [2] => GeeksforGeeks )

10. Arrays

Arrays in PHP are variables that store multiple values in one single variable. They can be indexed, associative and multidimensional array.

Function Description
array() Creates an array
count() Returns the number of elements in an array
array_push() Adds one or more elements to the end of an array
array_pop() Removes the last element from an array
array_shift() Removes the first element from an array
array_unshift() Adds one or more elements to the beginning of an array
array_merge() Merges one or more arrays
in_array() Checks if a value exists in an array
sort() Sorts an array
foreach loop PHP Iterates over each element in an array

PHP `

"GFG", "age" => 30 ]; // Print associative array element echo $person["name"] . "\n"; ?>

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Output

apple banana cherry GFG

11. Superglobals

PHP superglobals are built-in variables accessible everywhere, holding data like form input, sessions, cookies, server info, and files.

Superglobal Description
$_GET HTTP GET variables
$_POST HTTP POST variables
$_SERVER Server and execution environment information
$_SESSION Session variables
$_COOKIE HTTP cookies
$_FILES Uploaded files

12. Classes and Objects

In PHP, a Class is a blueprint for creating objects. It groups variables (properties) and functions (methods) into a single unit.

An **object is an instance of a class. It allows you to access the class’s properties and methods.

Term Description
class Defines a class
new Creates an object from a class
$this Refers to the current object inside the class
public Property/method accessible from anywhere
private Accessible only within the class
protected Accessible within the class and its subclasses
__construct Special method called automatically when object is created

PHP `

this−>brand=this->brand = this−>brand=brand; } // Method public function displayBrand() { echo "The car brand is: " . $this->brand; } } // Create an object of the class $myCar = new Car("Toyota"); // Call the method $myCar->displayBrand(); ?>

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Output

The car brand is: Toyota

Math

PHP offers numerous mathematical functions that allow you to perform operations like rounding, trigonometry, logarithms, and more. Here are the most commonly used functions:

Function Name Description
abs(x) Returns the absolute (positive) value of x
ceil(x) Rounds x up to the nearest integer
floor(x) Rounds x down to the nearest integer
round(x) Rounds x to the nearest integer
max(x, y, ...) Returns the highest value among the arguments
min(x, y, ...) Returns the lowest value among the arguments
sqrt(x) Returns the square root of x
pow(x, y) Returns x raised to the power of y
rand(min, max) Returns a random integer between min and max
mt_rand(min, max) Returns a better random integer (faster and more random)
pi() Returns the value of π (3.14159...)
deg2rad(x) Converts degrees to radians
rad2deg(x) Converts radians to degrees
bindec(string) Converts binary to decimal
decbin(number) Converts decimal to binary
hexdec(string) Converts hexadecimal to decimal
dechex(number) Converts decimal to hexadecimal
log(x, base) Returns the logarithm of x in the given base (default is e)
exp(x) Returns Euler's number raised to the power of x
fmod(x, y) Returns the remainder (modulo) of x ÷ y

14. PHP Errors

PHP Errors occur when something goes wrong while a script is running. Errors help developers identify and fix problems in the code.
There are different types of errors depending on the nature of the issue. Majorly there are the four types of the errors:

PHP Error Functions

PHP Error Functions manage how errors are reported, displayed, logged, or handled using built-in or custom error-handling mechanisms.

Function Name Description
error_reporting() Sets which PHP errors are reported.
ini_set() Sets configuration options at runtime (e.g., display_errors).
trigger_error() Generates a user-level error/warning/notice.
set_error_handler() Defines a custom function to handle errors.
restore_error_handler() Restores the previous error handler function.
set_exception_handler() Sets a function to handle uncaught exceptions.
restore_exception_handler() Restores the previous exception handler function.

PHP Error Constants

PHP error constants represent different error types like warnings, notices, and fatal errors, allowing developers to control error reporting behavior.

Constant Name Description
E_ERROR Fatal runtime errors.
E_WARNING Non-fatal run-time warnings.
E_PARSE Compile-time parse errors.
E_NOTICE Run-time notices indicating possible errors.
E_CORE_ERROR Errors during PHP's initial startup.
E_CORE_WARNING Warnings during PHP's initial startup.
E_COMPILE_ERROR Fatal compile-time errors.
E_COMPILE_WARNING Compile-time warnings.
E_USER_ERROR User-generated error message (via trigger_error()).
E_USER_WARNING User-generated warning message.
E_USER_NOTICE User-generated notice message.
E_STRICT Suggests code improvements for interoperability.
E_RECOVERABLE_ERROR Catchable fatal error.
E_DEPRECATED Warns about deprecated code.
E_USER_DEPRECATED User-generated deprecated warning.
E_ALL Reports all PHP errors (includes all above).

Benefits of Using PHP Cheatsheet

Below are some key benefits of a PHP Cheatsheet: