SoftwareDevPro/php_cheatsheet.md

## php_cheatsheet.md

      
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    PHP Cheatsheet

Including PHP in a file

<?php
    // place PHP code here
?>

Comments

// — Denotes comments that only span one line
# — Another way of producing single-line comments
/*...*/ — Everything between /* and */ is not executed, also works across several lines

Basic Naming Conventions

$firstName = 'Mike'  # variables
function updateProduct() # function names
class ProductItem # class names
const ACCESS_KEY = '123abc'; # constants

Basic Output

echo 'Hello PHP';

# Debug output
var_dump($some_var);
print_r($products);

Variables

Variable Declarations

$name = 'Joe';     # string
$isActive = false; # boolean
$number = 32;      # integer
$amount = 91.90;   # floating-point

Pre-defined variables


$GLOBALS — Used to access global variables from anywhere inside a PHP script
$_SERVER — Contains information about the locations of headers, paths, and scripts
$_GET — Can collect data that was sent in the URL or submitted in an HTML form
$_POST — Used to gather data from an HTML form and to pass variables
$_REQUEST — Also collects data after submitting an HTML form

Variable Handling Functions


boolval — Used to retrieve the boolean value of a variable
debug_zval_dump — Outputs a string representation of an internal zend value
empty — Checks whether a variable is empty or not
floatval — Get the float value of a variable (doubleval is another possibility)
get_defined_vars — Returns an array of all defined variables
get_resource_type — Returns the resource type
gettype — Retrieves the variable type
import_request_variables — Import GET/POST/Cookie variables into the global scope
intval — Find the integer value of a variable
is_array — Checks whether a variable is an array
is_bool — Finds out if a variable is a boolean
is_callable — Verify whether you can call the contents of a variable as a function
is_countable — Check whether the contents of a variable are countable
is_float — Find out if the type of a variable is float, alternatives: is_double and is_real
is_int — Check if the type of a variable is an integer, is_integer and is_long also works
is_iterable — Verify that a variable’s content is an iterable value
is_null — Checks whether a variable’s value is NULL
is_numeric — Find out if a variable is a number or a numeric string
is_object — Determines whether a variable is an object
is_resource — Check if a variable is a resource
is_scalar — Tests if a variable is a scalar
is_string — Find out whether the type of a variable is a string
isset — Determine if a variable has been set and is not NULL
print_r — Provides human-readable information about a variable
serialize — Generates a representation of a value that is storable
settype — Sets a variable’s type
strval — Retrieves the string value of a variable
unserialize — Creates a PHP value from a stored representation
unset — Unsets a variable
var_dump — Dumps information about a variable
var_export — Outputs or returns a string representation of a variable that can be parsed

Defining Constants

define(name, value, case_sensitive_true_false);

Default PHP Constants


LINE — Denotes the number of the current line in a file
FILE — Is the full path and filename of the file
DIR — The directory of the file
FUNCTION — Name of the function
CLASS — Class name, includes the namespace it was declared in
TRAIT — The trait name, also includes the namespace
METHOD —  The class method name
NAMESPACE — Name of the current namespace

PHP Operators

Arithmetic Operators


+ — Addition
- — Subtraction
* — Multiplication
/ — Division
% — Modulo (the remainder of value divided by another)
** — Exponentiation

Assignment Operators


+= — a += b is the same as a = a + b
-= — a -= b is the same as a = a – b
*= — a *= b is the same as a = a * b
/= — a /= b is the same as a = a / b
%= — a %= b is the same as a = a % b

Comparison Operators


== — Equal
=== — Identical
!= — Not equal
<> — Not equal
!== — Not identical
< — Less than
> — Greater than
<= — Less than or equal to
>= — Greater than or equal to
<=> — Less than, equal to, or greater than

Logical Operators


and — And
or — Or
xor — Exclusive or
! — Not
&& — And
|| — Or

Bitwise Operators


& — And
| — Or (inclusive or)
^ — Xor (exclusive or)
~ — Not
<< — Shift left
>> — Shift right

Error Control Operator

The @ sign can be used to prevent expressions from generating error messages.
Execution Operator

PHP supports one execution operator, which is `` (backticks). PHP will attempt to execute the contents of the backticks as a shell command.
Increment/Decrement Operators


++$v — Increments a variable by one, then returns it
$v++ — Returns a variable, then increments it by one
--$v — Decrements the variable by one, returns it afterward
$v-- — Returns the variable then decrements it by one

String Operators


. — Used to concatenate (mean combine) arguments
.= — Used to append the argument on the right to the left-side argument

PHP String Types


Single quotes — This is the simplest way. Just wrap your text in ' markers and PHP will handle it as a string.
Double quotes — As an alternative you can use ". When you do, it’s possible to use the escape characters below to display special characters.
heredoc — Begin a string with <<< and an identifier, then put the string in a new line. Close it in another line by repeating the identifier. heredoc behaves like double-quoted strings.
nowdoc — Is what heredoc is for double-quoted strings but for single quotes. It works the same way and eliminates the need for escape characters.

NOTE: Strings can contain variables, arrays, and objects.
String Usage Examples

# String concatenation
echo 'Hello ' . $name;

# String escape characters \n new line  \t tab  \\ backslash
echo "Hello Joe\nHello Jimmy";

# String interpolation
echo "Hello $name";

# String length
echo strlen($name);

# Remove space(s) before and after
echo trim($text);

# Convert to lowercase / uppercase
echo strtolower($email);
echo strtoupper($name);

# Converts the first character to uppercase
echo ucfirst($name);  # 'Joe'

# Replace text c by text d in $text
echo str_replace('c', 'd', $text);

# String Contains (PHP 8)
echo str_contains($name, 'oe')  # true

String Escape Characters


\n — Linefeed
\r — Carriage return
\t — Horizontal tab
\v — Vertical tab
\e — Escape
\f — Form feed
\ — Backslash
$ — Dollar sign
/' — Single quote
" — Double quote
[0-7]{1,3} — Character in octal notation
\x[0-9A-Fa-f]{1,2} — Character in hexadecimal notation
\u{[0-9A-Fa-f]+} — String as UTF-8 representation

PHP String Functions


addcslashes — Returns a string with backslashes in front of specified characters
addslashes — Returns a string with backslashes in front of characters that need to be escaped
bin2hex — Converts a string of ASCII characters to hexadecimal values
chop — Removes space or other characters from the right end of a string
chr — Returns a character from a specified ASCII value
chunk_split — Splits a string into a series of smaller chunks
convert_cyr_string — Converts a string from a Cyrillic character set to another
convert_uudecode — Decodes a uuencoded string
convert_uuencode — Encodes a string using uuencode
count_chars — Returns information about the characters in a string
crc32 — Calculates a 32-bit CRC for a string
crypt — Returns a hashed string
echo or echo '' — Outputs one or several strings
explode — Breaks down a string into an array
fprintf — Writes a formatted string to a specified output stream
get_html_translation_table — Returns the translation table used by htmlspecialchars() and htmlentities()
hebrev — Transforms Hebrew text to visual text
hebrevc — Converts Hebrew text to visual text and implements HTML line breaks
hex2bin — Translate hexadecimal values to ASCII characters
html_entity_decode — Turns HTML entities to characters
htmlentities — Converts characters to HTML entities
htmlspecialchars_decode — Transforms special HTML entities to characters
htmlspecialchars — Switches predefined characters to HTML entities
implode — Retrieves a string from the elements of an array, same as join
lcfirst — Changes a string’s first character to lowercase
levenshtein — Calculates the Levenshtein distance between two strings
localeconv — Returns information about numeric and monetary formatting for the locale
ltrim — Removes spaces or other characters from the left side of a string
md5 — Calculates the MD5 hash of a string and returns it
md5_file — Calculates the MD5 hash of a file
metaphone — Provides the metaphone key of a string
money_format — Returns a string as a currency string
nl_langinfo — Gives specific locale information
nl2br — Inserts HTML line breaks for each new line in a string
number_format — Formats a number including grouped thousands
ord — Returns the ASCII value of a string’s first character
parse_str — Parses a string into variables
print — Outputs one or several strings
printf — Outputs a formatted string
quoted_printable_decode — Converts a quoted-printable string to 8-bit binary
quoted_printable_encode — Goes from 8-bit string to a quoted-printable string
quotemeta — Returns a string with a backslash before metacharacters
rtrim — Strips whitespace or other characters from the right side of a string
setlocale — Sets locale information
sha1 — Calculates a string’s SHA-1 hash
sha1_file — Does the same for a file
similar_text — Determines the similarity between two strings
soundex — Calculates the soundex key of a string
sprintf — Returns a formatted string
sscanf — Parses input from a string according to a specified format
str_getcsv — Parses a CSV string into an array
str_ireplace — Replaces specified characters in a string with specified replacements (case-insensitive)
str_pad — Pads a string to a specified length
str_repeat — Repeats a string a preset number of times
str_replace — Replaces specified characters in a string (case-sensitive)
str_rot13 — Performs ROT13 encoding on a string
str_shuffle — Randomly shuffles the characters in a string
str_split — Splits strings into arrays
str_word_count — Returns the number of words in a string
strcasecmp — Case-insensitive comparison of two strings
strcmp — Binary safe string comparison (case sensitive)
strcoll — Compares two strings based on locale
strcspn — Returns the number of characters found in a string before the occurrence of specified characters
strip_tags — Removes HTML and PHP tags from a string
stripcslashes — Opposite of addcslashes()
stripslashes — Opposite of addslashes()
stripos — Finds the position of the first occurrence of a substring within a string (case insensitive)
stristr — Case-insensitive version of strstr()
strlen — Returns the length of a string
strnatcasecmp — Case-insensitive comparison of two strings using a “natural order” algorithm
strnatcmp — Same as the aforementioned but case sensitive
strncasecmp — String comparison of a defined number of characters (case insensitive)
strncmp — Same as above but case-sensitive
strpbrk — Searches a string for any number of characters
strpos — Returns the position of the first occurrence of a substring in a string (case sensitive)
strrchr — Finds the last occurrence of a string within another string
strrev — Reverses a string
strripos — Finds the position of the last occurrence of a string’s substring (case insensitive)
strrpos — Same as strripos but case sensitive
strspn — The number of characters in a string with only characters from a specified list
strstr — Case-sensitive search for the first occurrence of a string inside another string
strtok — Splits a string into smaller chunks
strtolower — Converts all characters in a string to lowercase
strtoupper — Same but for uppercase letters
strtr — Translates certain characters in a string, alternative: strchr
substr — Returns a specified part of a string
substr_compare — Compares two strings from a specified start position up to a certain length, optionally case sensitive
substr_count — Counts the number of times a substring occurs within a string
substr_replace — Replaces a substring with something else
trim — Removes space or other characters from both sides of a string
ucfirst — Transforms the first character of a string to uppercase
ucwords — Converts the first character of every word in a string to uppercase
vfprintf — Writes a formatted string to a specified output stream
vprintf — Outputs a formatted string
vsprintf — Writes a formatted string to a variable
wordwrap — Shortens a string to a given number of characters

Numbers

$ Check if numeric
echo is_numeric('12.99'); # true

$ Round a number
echo(round(0.75));  # returns 1
echo(round(0.40));  # returns 0

# Output a random number
echo(rand(10, 100)); # 32

Conditionals

# Ternary operator (true : false)
echo $isValid ? 'user valid' : 'user not valid';

# Null Coalesce Operator
echo $name ?? 'Joe';  # output 'Joe' if $name is null

# Null Coalesce Assignment
$name ??= 'Joe';

# Null Safe Operator (PHP 8) will return null if one ? is null
echo $user?->profile?->activate();

# Null Safe + Null Coalesce (if null will return 'No user profile')
echo $user?->profile?->activate() ?? 'Not applicable';

# Spaceship operator returns -1 0 1
$names = ['Mike', 'Paul', 'John']
usort($names, function($a, $b) {
    return $a <=> $b;
}
# ['John', 'Mike', 'Paul']

# Will return false when convert as boolean
false, 0, 0.0, null, unset, '0', '', []

# Conditionals
if ($condition == 20) {
    echo 'condition 20';
} elseif  ($condition == 10) {
    echo 'condition 10';
} else {
    echo 'anything except 20 and 10';
}

# Everything on one line
if ($isActive) return true;

# Switch Statement
switch (n) {
    case x:
        code to execute if n=x;
        break;
    case y:
        code to execute if n=y;
        break;
    case z:
        code to execute if n=z;
        break;
    // add more cases as needed
    default:
        code to execute if n is neither of the above;
}

# Match Expression (PHP 8)
$type = match($color) {
    'red' => 'danger',
    'yellow', 'orange' => 'warning',
    'green' => 'success',
    default => 'unknown'
};

Looping

# for loop

for ($i = 0; $i < 20; $i++) {
    echo "i value = " . i;
}

# while loop

$number = 1;
while ($num < 10) {
    echo 'value : ' . $num;
    $num += 1;
}

# do while

$num = 1;
do {
    echo 'value : ' . $num;
    $num += 1;
} while ($num < 10);

# foreach with break / continue example

$values = ['one', 'two', 'three'];

foreach ($values as $val) {
    if ($val === 'two') {
        break; # exit loop
    } elseif ($val === 'three') {
        continue; # next loop iteration
    }
}

PHP Arrays

Declaring an array

$languages = array("C++", "Java", "PHP");
echo "What is your favorite Language? Is it " . $languages[0] . ", " . $languages[1] . " or " . $languages[2] . "?";

Different Types of Arrays in PHP:


Indexed arrays – Arrays that have a numeric index
Associative arrays – Arrays where the keys are named
Multidimensional arrays – Arrays that contain one or more other arrays

Array Examples

# Array declaration
$names = ['Joe', 'James', 'Peter', 'Zeus'];

# Append to array
$names[] = 'Jessie';

# Array merge
$array3 = array_merge($array1, $array2);

# Array Concat with Spread Operator
$names = ['Joe', 'James', 'Peter'];
$people = ['John', ...$names]; // ['John', 'Joe', 'James', 'Peter'];

# Remove array entry
unset($names['Joe']);

# Array to string
echo implode(', ', $names) // output James, Peter

# String to Array
echo explode(',', $text);

# Direct access
echo $names[1] # output James

# Loop for each array entry
foreach($names as $name) {
   echo 'Hello ' . $name;
}

# Number of items in a Array
echo count($names);  

# Associative array:
$person = ['age' => 32, 'gender' => 'female'];

# Add to associative array:
$person['name'] = 'Amanda';

# Loop through associative array key => value:
foreach($names as $key => $value) {
   echo $key . ' : ' . $value;
}

# Check if a specific key exist
echo array_key_exist('age', $person);

# Return keys
echo array_keys($person); # ['age', 'gender']

# Return values
echo array_values($person) # [32, 'female']

# Array filter (return a filtered array)
$filteredPeople = array_filter($people, function ($person) {
    return $names->active;
})

# Array map (return transform array):
$onlyNames = array_map(function($person) {
    return [‘name’ => $person->name];
}, $people);

# Search associative array
$items = [
        ['id' => '100', 'name' => 'product 1'],
        ['id' => '200', 'name' => 'product 2'],
        ['id' => '300', 'name' => 'product 3'],
        ['id' => '400', 'name' => 'product 4'],
];

# search all value in the 'name' column
$found_key = array_search('product 4', array_column($items, 'name'));


Array Functions


array_change_key_case — Changes all keys in an array to uppercase or lowercase
array_chunk — Splits an array into chunks
array_column — Retrieves the values from a single column in an array
array_combine — Merges the keys from one array and the values from another into a new array
array_count_values — Counts all values in an array
array_diff — Compares arrays, returns the difference (values only)
array_diff_assoc — Compares arrays, returns the difference (values and keys)
array_diff_key — Compares arrays, returns the difference (keys only)
array_diff_uassoc — Compares arrays (keys and values) through a user callback function
array_diff_ukey — Compares arrays (keys only) through a user callback function
array_fill — Fills an array with values
array_fill_keys — Fills an array with values, specifying keys
array_filter — Filters the elements of an array via a callback function
array_flip — Exchanges all keys in an array with their associated values
array_intersect — Compare arrays and return their matches (values only)
array_intersect_assoc — Compare arrays and return their matches (keys and values)
array_intersect_key — Compare arrays and return their matches (keys only)
array_intersect_uassoc — Compare arrays via a user-defined callback function (keys and values)
array_intersect_ukey — Compare arrays via a user-defined callback function (keys only)
array_key_exists — Checks if a specified key exists in an array, alternative: key_exists
array_keys — Returns all keys or a subset of keys in an array
array_map — Applies a callback to the elements of a given array
array_merge — Merge one or several arrays
array_merge_recursive — Merge one or more arrays recursively
array_multisort — Sorts of multiple or multi-dimensional arrays
array_pad — Inserts a specified number of items (with a specified value) into an array
array_pop — Deletes an element from the end of an array
array_product — Calculate the product of all values in an array
array_push — Push one or several elements to the end of the array
array_rand — Pick one or more random entries out of an array
array_reduce — Reduce the array to a single string using a user-defined function
array_replace — Replaces elements in the first array with values from following arrays
array_replace_recursive — Recursively replaces elements from later arrays into the first array
array_reverse — Returns an array in reverse order
array_search — Searches the array for a given value and returns the first key if successful
array_shift — Shifts an element from the beginning of an array
array_slice — Extracts a slice of an array
array_splice — Removes a portion of the array and replaces it
array_sum — Calculate the sum of the values in an array
array_udiff — Compare arrays and return the difference using a user function (values only)
array_udiff_assoc — Compare arrays and return the difference using default and a user function (keys and values)
array_udiff_uassoc — Compare arrays and return the difference using two user functions (values and keys)
array_uintersect — Compare arrays and return the matches via user function (values only)
array_uintersect_assoc — Compare arrays and return the matches via a default user function (keys and values)
array_uintersect_uassoc — Compare arrays and return the matches via two user functions (keys and values)
array_unique — Removes duplicate values from an array
array_unshift — Adds one or more elements to the beginning of an array
array_values — Returns all values of an array
array_walk — Applies a user function to every element in an array
array_walk_recursive — Recursively applies a user function to every element of an array
arsort — Sorts an associative array in descending order according to the value
asort — Sorts an associative array in ascending order according to the value
compact — Create an array containing variables and their values
count — Count all elements in an array, alternatively use sizeof
current — Returns the current element in an array, an alternative is pos
each — Return the current key and value pair from an array
end — Set the internal pointer to the last element of an array
extract — Import variables from an array into the current symbol table
in_array — Checks if a value exists in an array
key — Fetches a key from an array
krsort — Sorts an associative array by key in reverse order
ksort — Sorts an associative array by key
list — Assigns variables as if they were an array
natcasesort — Sorts an array using a “natural order” algorithm independent of case
natsort — Sorts an array using a “natural order” algorithm
next — Advance the internal pointer of an array
prev — Move the internal array pointer backward
range — Creates an array from a range of elements
reset — Set the internal array pointer to its first element
rsort — Sort an array in reverse order
shuffle — Shuffle an array
sort — Sorts an indexed array in ascending order
uasort — Sorts an array with a user-defined comparison function
uksort — Arrange an array by keys using a user-defined comparison function
usort — Categorize an array by values using a comparison function defined by the user

Function Examples

# Function declaration
function name($firstName, $lastName = 'defaultvalue') {
    return "$firstName $lastName"
}

# Function call
name('John', 'Smith');

# Function call with named parameters (PHP 8)
name(firstName: 'John', lastName: 'Smith'); # order can change

# Function variables params
function name(...$params) {
    return $params[0] . “ “ . params[1];
}

# Closure function
Route::get('/', function () {
     return view('welcome');
});

# Arrow functions
Route::get('/', fn () => view('welcome');

Files

# Open a file to read
$file = fopen("foo.txt", "r");

# Output lines until EOF is reached
while(! feof($file)) {
  $line = fgets($file);
  echo $line. "<br>";
}

fclose($file);

# File write
$file = fopen('test.csv', 'a');
$array = ['name' => 'Mike', 'age' => 45];

# Write key name as csv header
fputcsv($file, array_keys($array[0]));

# Write lines (format as csv)
foreach ($array as $row) {
    fputcsv($file, $row);
}

fclose($file);

Errors

Error Examples

# Throw an error
if (someCondition) {
    throw new Exception('error');
}

# Catch the Error
try {
  $obj->check($data);

} catch (Exception $e) {
    echo $e->getMessage();
}

Error Functions


debug_backtrace — Used to generate a backtrace
debug_print_backtrace — Prints a backtrace
error_get_last — Gets the last error that occurred
error_log — Sends an error message to the web server’s log, a file or a mail account
error_reporting — Specifies which PHP errors are reported
restore_error_handler — Reverts to the previous error handler function
restore_exception_handler — Goes back to the previous exception handler
set_error_handler — Sets a user-defined function to handle script errors
set_exception_handler — Sets an exception handler function defined by the user
trigger_error — Generates a user-level error message, you can also use user_error()

Error Constants


E_ERROR — Fatal run-time errors that cause the halting of the script and can’t be recovered from
E_WARNING — Non-fatal run-time errors, execution of the script continues
E_PARSE — Compile-time parse errors, should only be generated by the parser
E_NOTICE — Run-time notices that indicate a possible error
E_CORE_ERROR — Fatal errors at PHP initialization, like an E_ERROR in PHP core
E_CORE_WARNING — Non-fatal errors at PHP startup, similar to E_WARNING but in PHP core
E_COMPILE_ERROR — Fatal compile-time errors generated by the Zend Scripting Engine
E_COMPILE_WARNING — Non-fatal compile-time errors by the Zend Scripting Engine
E_USER_ERROR — Fatal user-generated error, set by the programmer using trigger_error()
E_USER_WARNING — Non-fatal user-generated warning
E_USER_NOTICE — User-generated notice by trigger_error()
E_STRICT — Suggestions by PHP to improve your code (needs to be enabled)
E_RECOVERABLE_ERROR — Catchable fatal error caught by a user-defined handle
E_DEPRECATED — Enable this to receive warnings about a code which is not future-proof
E_USER_DEPRECATED — User-generated warning for deprecated code
E_ALL — All errors and warnings except E_STRICT

OOP (Object Oriented Programming)

# Basic class declaration
class Person {
  # ...
}

# object instantiation
$user = new User

# Class properties and constructor
class User {

   protected $userName;
   protected $userId;

   public function __construct($userName, $userId) {
        $this->userName = $firstName;
        $this->userId = $userId
   }

# Constructor Property Promotion (PHP 8)
class User {

    public function __construct(protected $userName, protected $userId) {
      # ...
    }

# Static constructor
public static function create(...$params) {
    return new self($params)
}
$user = User::create(‘Joe Smith’, ‘jsmith1982’);

# Class inheritance
class SuperUser extends User {

    public function username() {
        parent::username();
        echo 'Override method';  
    }
}

# Static Method
class HelloWorld {
  public static function hello() {
    echo "Hello World!";
  }
}

# Call static method
HelloWorld::hello();

# Static method internal call
class HelloWorld {
  public static function hello() {
    echo "Hello World!";
  }

  public function __construct() {
    self::hello();
  }
}
new HelloWorld();

# Interfaces
interface Animal {
  public function makeSound();
}

class Dog implements Animal {
  public function makeSound() {
    echo "ruff!!!";
  }
}
$animal = new Dog();
$animal->makeSound();

# Trait (mix-in)
trait HelloWorld {
    public function sayHello() {
        echo 'Hello World!';
    }
}

class Greetings {
    use HelloWorld;
}

$object = new Greetings();
$object->sayHello();

PHP HTTP Related Functionality

PHP has the ability to manipulate data sent to the browser from the webserver.
HTTP Functions


header — Sends a raw HTTP header to the browser
headers_list — A list of response headers ready to send (or already sent)
headers_sent — Checks if and where the HTTP headers have been sent
setcookie — Defines a cookie to be sent along with the rest of the HTTP headers
setrawcookie — Defines a cookie (without URL encoding) to be sent along

MySQL

Many platforms that are based on PHP work with a MySQL database in the background.
MySQL Functions


mysqli_affected_rows — The number of affected rows in the previous MySQL operation
mysqli_autocommit — Turn auto-committing database modifications on or off
mysqli_change_user — Changes the user of the specified database connection
mysqli_character_set_name — The default character set for the database connection
mysqli_close — Closes an open database connection
mysqli_commit — Commits the current transaction
mysqli_connect_errno — The error code from the last connection error
mysqli_connect_error — The error description from the last connection error
mysqli_connect — Opens a new connection to the MySQL server
mysqli_data_seek — Moves the result pointer to an arbitrary row in the result set
mysqli_debug — Performs debugging operations
mysqli_dump_debug_info — Dumps debugging information into a log
mysqli_errno — The last error code for the most recent function call
mysqli_error_list — A list of errors for the most recent function call
mysqli_error — The last error description for the most recent function call
mysqli_fetch_all — Fetches all result rows as an array
mysqli_fetch_array — Fetches a result row as an associative, a numeric array, or both
mysqli_fetch_assoc — Fetches a result row as an associative array
mysqli_fetch_field_direct — Metadata for a single field as an object
mysqli_fetch_field — The next field in the result set as an object
mysqli_fetch_fields — An array of objects that represent the fields in a result set
mysqli_fetch_lengths — The lengths of the columns of the current row in the result set
mysqli_fetch_object — The current row of a result set as an object
mysqli_fetch_row — Fetches one row from a result set and returns it as an enumerated array
mysqli_field_count — The number of columns for the most recent query
mysqli_field_seek — Sets the field cursor to the given field offset
mysqli_field_tell — The position of the field cursor
mysqli_free_result — Frees the memory associated with a result
mysqli_get_charset — A character set object
mysqli_get_client_info — The MySQL client library version
mysqli_get_client_stats — Returns client per-process statistics
mysqli_get_client_version — The MySQL client library version as an integer
mysqli_get_connection_stats — Statistics about the client connection
mysqli_get_host_info — The MySQL server hostname and the connection type
mysqli_get_proto_info — The MySQL protocol version
mysqli_get_server_info — Returns the MySQL server version
mysqli_get_server_version — The MySQL server version as an integer
mysqli_info — Returns information about the most recently executed query
mysqli_init — Initializes MySQLi and returns a resource for use with mysqli_real_connect()
mysqli_insert_id — Returns the auto-generated ID used in the last query
mysqli_kill — Asks the server to kill a MySQL thread
mysqli_more_results — Checks if there are more results from a multi-query
mysqli_multi_query — Performs one or more queries on the database
mysqli_next_result — Prepares the next result set from mysqli_multi_query()
mysqli_num_fields — The number of fields in a result set
mysqli_num_rows — The number of rows in a result set
mysqli_options — Sets extra connect options and affect behavior for a connection
mysqli_ping — Pings a server connection or tries to reconnect if it has gone down
mysqli_prepare — Prepares an SQL statement for execution
mysqli_query — Performs a query against the database
mysqli_real_connect — Opens a new connection to the MySQL server
mysqli_real_escape_string — Escapes special characters in a string for use in an SQL statement
mysqli_real_query — Executes an SQL query
mysqli_reap_async_query — Returns the result from async query
mysqli_refresh — Refreshes tables or caches or resets the replication server information
mysqli_rollback — Rolls back the current transaction for the database
mysqli_select_db — Changes the default database for the connection
mysqli_set_charset — Sets the default client character set
mysqli_set_local_infile_default — Unsets a user-defined handler for the LOAD LOCAL INFILE command
mysqli_set_local_infile_handler — Sets a callback function for the LOAD DATA LOCAL INFILE command
mysqli_sqlstate — Returns the SQLSTATE error code for the last MySQL operation
mysqli_ssl_set — Establishes secure connections using SSL
mysqli_stat — The current system status
mysqli_stmt_init — Initializes a statement and returns an object for use with mysqli_stmt_prepare()
mysqli_store_result — Transfers a result set from the last query
mysqli_thread_id — The thread ID for the current connection
mysqli_thread_safe — Returns if the client library is compiled as thread-safe
mysqli_use_result — Initiates the retrieval of a result set from the last query executed using the mysqli_real_query()
mysqli_warning_count — The number of warnings from the last query in the connection

Date and Time

PHP has a number of date/time related functions.
Date/Time Functions


checkdate — Checks the validity of a Gregorian date
date_add — Adds a number of days, months, years, hours, minutes and seconds to a date object
date_create_from_format — Returns a formatted DateTime object
date_create — Creates a new DateTime object
date_date_set — Sets a new date
date_default_timezone_get — Returns the default timezone used by all functions
date_default_timezone_set — Sets the default timezone
date_diff — Calculates the difference between two dates
date_format — Returns a date formatted according to a specific format
date_get_last_errors — Returns warnings or errors found in a date string
date_interval_create_from_date_string — Sets up a DateInterval from relative parts of a string
date_interval_format — Formats an interval
date_isodate_set — Sets a date according to ISO 8601 standards
date_modify — Modifies the timestamp
date_offset_get — Returns the offset of the timezone
date_parse_from_format — Returns an array with detailed information about a specified date, according to a specified format
date_parse — Returns an array with detailed information about a specified date
date_sub — Subtracts days, months, years, hours, minutes and seconds from a date
date_sun_info — Returns an array containing information about sunset/sunrise and twilight begin/end for a specified day and location
date_sunrise — The sunrise time for a specified day and location
date_sunset — The sunset time for a specified day and location
date_time_set — Sets the time
date_timestamp_get — Returns the Unix timestamp
date_timestamp_set — Sets the date and time based on a Unix timestamp
date_timezone_get — Returns the time zone of a given DateTime object
date_timezone_set — Sets the time zone for a DateTime object
date — Formats a local date and time
getdate — Date/time information of a timestamp or the current local date/time
gettimeofday — The current time
gmdate — Formats a GMT/UTC date and time
gmmktime — The Unix timestamp for a GMT date
gmstrftime — Formats a GMT/UTC date and time according to locale settings
idate — Formats a local time/date as an integer
localtime — The local time
microtime — The current Unix timestamp with microseconds
mktime — The Unix timestamp for a date
strftime — Formats a local time and/or date according to locale settings
strptime — Parses a time/date generated with strftime
strtotime — Transforms an English textual DateTime into a Unix timestamp
time — The current time as a Unix timestamp
timezone_abbreviations_list — Returns an array containing dst, offset, and the timezone name
timezone_identifiers_list — An indexed array with all timezone identifiers
timezone_location_get — Location information for a specified timezone
timezone_name_from_abbr — Returns the timezone name from an abbreviation
timezone_name_get — The name of the timezone
timezone_offset_get — The timezone offset from GMT
timezone_open — Creates a new DateTimeZone object
timezone_transitions_get — Returns all transitions for the timezone
timezone_version_get — Returns the version of the timezonedb

Date and Time Formatting


d — 01 to 31
j — 1 to 31
D — Mon through Sun
l — Sunday through Saturday
N — 1 (for Mon) through 7 (for Sat)
w — 0 (for Sun) through 6 (for Sat)
m — Months, 01 through 12
n — Months, 1 through 12
F — January through December
M — Jan through Dec
Y — Four digits year (e.g. 2018)
y — Two digits year (e.g. 18)
L — Defines whether it’s a leap year (1 or 0)
a — am and pm
A — AM and PM
g — Hours 1 through 12
h — Hours 01 through 12
G — Hours 0 through 23
H — Hours 00 through 23
i — Minutes 00 to 59
s — Seconds 00 to 59

Regular Expressions

Syntax

$expr = "/pattern/i";

RegEx Functions


preg_match - Returns 1 if the pattern was found in the string and 0 if not
preg_match_all - Returns the number of times the pattern was found in the string, which may also be 0
preg_replace - Returns a new string where matched patterns have been replaced with another string

RegEx Modifiers


i - Performs a case-insensitive search
m - Performs a multiline search (patterns that search for the beginning or end of a string will match the beginning or end of each line)
u - Enables correct matching of UTF-8 encoded patterns

RegEx Patterns


[abc] – Find one character from the options between the brackets
[^abc] – Find any character NOT between the brackets
[0-9] – Find one character from the range 0 to 9

Metacharacters


| - Find a match for any one of the patterns separated by | as in: cat|dog|fish
. - Find just one instance of any character
^ - Finds a match as the beginning of a string as in: ^Hello
$ - Finds a match at the end of the string as in: World$
\d - Find a digit
\s - Find a whitespace character
\b - Find a match at the beginning of a word like this: \bWORD, or at the end of a word like this: WORD\b
\uxxxx - Find the Unicode character specified by the hexadecimal number xxxx

Quantifiers


n+ - Matches any string that contains at least one n
n* - Matches any string that contains zero or more occurrences of n
n? - Matches any string that contains zero or one occurrences of n
n{x} - Matches any string that contains a sequence of X n’s
n{x,y} - Matches any string that contains a sequence of X to Y n’s
n{x,} - Matches any string that contains a sequence of at least X n’s

Grouping

You can use parentheses ( ) to apply quantifiers to entire patterns. They can also be used to select parts of the pattern to be used as a match.
$str = "Apples and bananas.";
$pattern = "/ba(na){2}/i";
echo preg_match($pattern, $str); // Outputs 1

PHP Filters

Filters are used to validate and filter data that is coming from insecure sources.
Functions


filter_has_var — Checks if a variable of the specified type exists
filter_id — Returns the ID belonging to a named filter
filter_input — Retrieves a specified external variable by name and optionally filters it
filter_input_array — Pulls external variables and optionally filters them
filter_list — Returns a list of all supported filters
filter_var_array — Gets multiple variables and optionally filters them
filter_var — Filters a variable with a specified filter

Constants


FILTER_VALIDATE_BOOLEAN — Validates a boolean
FILTER_VALIDATE_EMAIL — Certifies an e-mail address
FILTER_VALIDATE_FLOAT — Confirms a float
FILTER_VALIDATE_INT — Verifies an integer
FILTER_VALIDATE_IP — Validates an IP address
FILTER_VALIDATE_REGEXP — Confirms a regular expression
FILTER_VALIDATE_URL — Validates a URL
FILTER_SANITIZE_EMAIL — Removes all illegal characters from an e-mail address
FILTER_SANITIZE_ENCODED — Removes/Encodes special characters
FILTER_SANITIZE_MAGIC_QUOTES — Applies addslashes()
FILTER_SANITIZE_NUMBER_FLOAT — Removes all characters, except digits, +- and .,eE
FILTER_SANITIZE_NUMBER_INT — Gets rid of all characters except digits and + –
FILTER_SANITIZE_SPECIAL_CHARS — Removes special characters
FILTER_SANITIZE_FULL_SPECIAL_CHARS — Converts special characters to HTML entities
FILTER_SANITIZE_STRING — Removes tags/special characters from a string, alternative: FILTER_SANITIZE_STRIPPED
FILTER_SANITIZE_URL — Rids all illegal characters from a URL
FILTER_UNSAFE_RAW —Do nothing, optionally strip/encode special characters
FILTER_CALLBACK — Call a user-defined function to filter data