PHP CheatSheet for Developers

Escape Sequence

Command	Description
`// Comment Message`	This is a single-line comment
`$Title = "Title"`	Defining Variables
`\n`	New Line
`\r`	It inserts a carriage return in the text at this point.
`\t`	It gives a horizontal tab space
`\v`	It gives a vertical tab space
`\\`	It adds a backslash
`\$`	Print the next character as a dollar, not as part of a variable
`\'`	Print the next character as a double quote, not a string closer
`\"`	Print the next character as a double quote, not a string closer

Operators

Arithmetic Operators

operator	name	syntax
`+`	Addition	$x +$ y
`-`	Subtraction	$x -$ y
`*`	Multiplication	$x *$ y
`/`	Division	$x /$ y
`%`	Modulus	$x$ y
`**`	Exponentiation	$x * *$ y

Comparison Operators

operator	name	syntax
`==`	Equal	$x ==$ y
`===`	Identical	$x ===$ y
`!=`	Not equal	$x! =$ y
`<>`	Not equal	$x <>$ y
`!==`	Not identical	$x! ==$ y
`>`	Greater than	$x >$ y
`<`	Less than	$x <$ y
`>=`	Greater than or equal to	$x >=$ y
`<=`	Less than or equal to	$x <=$ y
`<=>`	Spaceship	$x <=>$ y

Logical Operators

operator	name	syntax
`and`	And	$x an d$ y
`or`	Or	$x or$ y
`xor`	Xor	$xx or$ y
`&&`	And	$x &&$ y
`\|`	Or	$x ∥$ y
`!`	Not	!$x

String Operators

operator	name	syntax
`.`	Concatenation	$t x t 1.$ txt2
`.=`	Concatenation assignment	$t x t 1. =$ txt2

Array Operators

operator	name	syntax
`+`	Union	$x +$ y
`==`	Equality	$x ==$ y
`===`	Identity	$x ===$ y
`!=`	Inequality	$x! =$ y
`<>`	Inequality	$x <>$ y
`!==`	Non-identity	$x! ==$ y

Conditional Assignment Operators

operator	name	syntax
`?:`	Ternary	$x = expr1 ? expr2 : expr3
`??`	Null coalescing	$x = expr1 ?? expr2

Increment/Decrement Operators

operator	name	description
`++$x`	Pre-increment	Increments $x by one
`$x++`	Post-increment	Returns $x, t h e nin cre m e n t s$ x by one
`--$x`	Pre-decrement	Decrements $x b yo n e, t h e n re t u r n s$ x
`$x--`	Post-decrement	Returns $x, t h e n d ecre m e n t s$ x by one

Super global variable

keyword	description
`$GLOBALS`	used to access global variables from anywhere in the PHP script
`$_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 with method="post"
`$_GET`	used to collect form data after submitting an HTML form with method="get"
`$_FILES`	an associative array containing items uploaded via HTTP POST method
`$_ENV`	An associative array of variables passed to the current script via the environment method.
`$_COOKIE`	etrieve the value of the cookie
`$_SESSION`	A session is a way to store information (in variables) to be used across multiple pages.

Important keywords $_SERVER

Element/Code	Description
`$_SERVER['PHP_SELF']`	Returns the filename of the currently executing script
`$_SERVER['GATEWAY_INTERFACE']`	Returns the version of the Common Gateway Interface (CGI) the server is using
`$_SERVER['SERVER_ADDR']`	Returns the IP address of the host server
`$_SERVER['SERVER_NAME']`	Returns the name of the host server (such as www.w3schools.com)
`$_SERVER['SERVER_SOFTWARE']`	Returns the server identification string (such as Apache/2.2.24)
`$_SERVER['SERVER_PROTOCOL']`	Returns the name and revision of the information protocol (such as HTTP/1.1)
`$_SERVER['REQUEST_METHOD']`	Returns the request method used to access the page (such as POST)
`$_SERVER['REQUEST_TIME']`	Returns the timestamp of the start of the request (such as 1377687496)
`$_SERVER['QUERY_STRING']`	Returns the query string if the page is accessed via a query string
`$_SERVER['HTTP_ACCEPT']`	Returns the Accept header from the current request
`$_SERVER['HTTP_ACCEPT_CHARSET']`	Returns the Accept_Charset header from the current request (such as utf-8,ISO-8859-1)
`$_SERVER['HTTP_HOST']`	Returns the Host header from the current request
`$_SERVER['HTTP_REFERER']`	Returns the complete URL of the current page (not reliable because not all user-agents support it)
`$_SERVER['HTTPS']`	Is the script queried through a secure HTTP protocol
`$_SERVER['REMOTE_ADDR']`	Returns the IP address from where the user is viewing the current page
`$_SERVER['REMOTE_HOST']`	Returns the Host name from where the user is viewing the current page
`$_SERVER['REMOTE_PORT']`	Returns the port being used on the user's machine to communicate with the web server
`$_SERVER['SCRIPT_FILENAME']`	Returns the absolute pathname of the currently executing script
`$_SERVER['SERVER_ADMIN']`	Returns the value given to the SERVER_ADMIN directive in the web server configuration file (if your script runs on a virtual host, it will be the value defined for that virtual host) (such as [email protected])
`$_SERVER['SERVER_PORT']`	Returns the port on the server machine being used by the web server for communication (such as 80)
`$_SERVER['SERVER_SIGNATURE']`	Returns the server version and virtual host name which are added to server-generated pages
`$_SERVER['PATH_TRANSLATED']`	Returns the file system based path to the current script
`$_SERVER['SCRIPT_NAME']`	Returns the path of the current script
`$_SERVER['SCRIPT_URI']`	Returns the URI of the current page

Functions

Array Function

Function	Description
`count(arr)`	Returns the length of an array arr
`print_r(arr)`	Prints the arr’s contents
`array_pop(arr)`	Pops (removes) an element off the end of the array arr
`array_shift(arr)`	Shifts (removes) an element off the beginning of the array arr
`array_push(arr, el)`	Pushes (adds) one or more elements onto the end of the array arr
`array_unshift(arr, el)`	Prepends one or more elements to the beginning of the array arr
`sort(arr)`	Sorts the array arr
`array_reverse(arr)`	Returns an array with elements of arr in reverse order
`in_array(el, arr)`	Returns whether a value el exists in an array arr
`list(a, b, ...)`	Assigns variables as if they were an array
`implode(glue, pieces)`	Joins array elements (pieces) with a string (glue)
`array_rand(arr)`	Randomly selects a random entry from the array and returns the key(or keys) of the random entries

PHP standard functions

Function	Description
`isset(el)`	Will return false if el has been assigned the constant NULL, el has not been set to any value yet (undefined) el has been deleted using the unset function
`print str` or `echo str`	Prints str
`time()`	Returns the current time in seconds
`date(format, time)`	Converts an optional time in seconds to a date based on format
`mt_rand(min, max)`	Returns a random integer between min and max (inclusive)
`header(string)`	Sends a raw HTTP header.
`die(message)`	Ends execution and sends back optional message
`include "path"`	Includes and evaluates the specified file path such as "hidden/config.php"

String function

Function	Description
`strlen(s)`	Returns the length of a string s
`strpos(str, substr)`	Returns the position of the first occurrence of substr in str, or FALSE if not found
`substr(s, start,len)`	Returns a substring of s starting at start and up to len characters in length. If s is less than start characters long, FALSE will be returned
`trim(s)`	Strips whitespace characters from both ends of a string s
`strtolower(s)`	Returns a lowercase version of s
`strtoupper(s)`	Returns an uppercase version of s
`explode(delimiter,s)`	Returns an array of substrings of s split by delimiter

File function

Function	Description
`file(path, [int flags = 0])`	Reads entire file path into an array. Optional flags parameter can be passed in such as FILE_IGNORE_NEW_LINES or FILE_SKIP_EMPTY_LINES
`file_exists(path)`	Returns whether a file or directory path exists
`file_get_contents(path)`	Reads entire file path into a string
`file_put_contents(path, data)`	Writes a string data to a file path
`scandir(path)`	Returns an array of all files and directories inside the specified path including . and ..
`glob(pattern)`	Returns an array of path names matching pattern
`basename(path)`	Given a filename path, this function will strip any leading directory from a file path and return just the filename

Read File

Modes	Description	pointer
`r`	Open a file for read only.	File pointer starts at the beginning of the file
`w`	Open a file for write only.	Erases the contents of the file or creates a new file if it doesn't exist. File pointer starts at the beginning of the file
`a`	Open a file for write only.	The existing data in file is preserved. File pointer starts at the end of the file. Creates a new file if the file doesn't exist
`x`	Creates a new file for write only.	Returns FALSE and an error if file already exists
`r+`	Open a file for read/write.	File pointer starts at the beginning of the file
`w+`	Open a file for read/write.	Erases the contents of the file or creates a new file if it doesn't exist. File pointer starts at the beginning of the file
`a+`	Open a file for read/write.	The existing data in file is preserved. File pointer starts at the end of the file. Creates a new file if the file doesn't exist
`x+`	Creates a new file for read/write.	Returns FALSE and an error if file already exists

Cookies and Session

keyword	Description
`setcookie(name, value)`	used to set cookie with HTTP response
`$_COOKIE`	etrieve the value of the cookie
`session_start()`	A session is started
`$_SESSION`	Session variables are set with the PHP global variable
`session_unset() and session_destroy()`	To remove all global session variables and destroy the session

Most Important Function

calender function

Function	Description
`cal_days_in_month()`	Returns the number of days in a month for a specified year and calendar
`cal_from_jd()`	Converts a Julian Day Count into a date of a specified calendar
`cal_info()`	Returns information about a specified calendar
`cal_to_jd()`	Converts a date in a specified calendar to Julian Day Count
`easter_date()`	Returns the Unix timestamp for midnight on Easter of a specified year
`easter_days()`	Returns the number of days after March 21, that the Easter Day is in a specified year
`frenchtojd()`	Converts a French Republican date to a Julian Day Count
`gregoriantojd()`	Converts a Gregorian date to a Julian Day Count
`jddayofweek()`	Returns the day of the week
`jdmonthname()`	Returns a month name
`jdtofrench()`	Converts a Julian Day Count to a French Republican date
`jdtogregorian()`	Converts a Julian Day Count to a Gregorian date
`jdtojewish()`	Converts a Julian Day Count to a Jewish date
`jdtojulian()`	Converts a Julian Day Count to a Julian date
`jdtounix()`	Converts Julian Day Count to Unix timestamp
`jewishtojd()`	Converts a Jewish date to a Julian Day Count
`juliantojd()`	Converts a Julian date to a Julian Day Count
`unixtojd()`	Converts Unix timestamp to Julian Day Count

Date/time Function

Function	Description
`checkdate()`	Validates a Gregorian date
`date_add()`	Adds days, months, years, hours, minutes, and seconds to a date
`date_create_from_format()`	Returns a new DateTime object formatted according to a specified format
`date_create()`	Returns a new DateTime object
`date_date_set()`	Sets a new date
`date_default_timezone_get()`	Returns the default timezone used by all date/time functions
`date_default_timezone_set()`	Sets the default timezone used by all date/time functions
`date_diff()`	Returns the difference between two dates
`date_format()`	Returns a date formatted according to a specified format
`date_get_last_errors()`	Returns the warnings/errors found in a date string
`date_interval_create_from_date_string()`	Sets up a DateInterval from the relative parts of the string
`date_interval_format()`	Formats the interval
`date_isodate_set()`	Sets the ISO date
`date_modify()`	Modifies the timestamp
`date_offset_get()`	Returns the timezone offset
`date_parse_from_format()`	Returns an associative array with detailed info about a specified date, according to a specified format
`date_parse()`	Returns an associative array with detailed info about a specified date
`date_sub()`	Subtracts days, months, years, hours, minutes, and seconds from a date
`date_sun_info()`	Returns an array containing info about sunset/sunrise and twilight begin/end, for a specified day and location
`date_sunrise()`	Returns the sunrise time for a specified day and location
`date_sunset()`	Returns 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 the given DateTime object
`date_timezone_set()`	Sets the time zone for the DateTime object
`date()`	Formats a local date and time
`getdate()`	Returns date/time information of a timestamp or the current local date/time
`gettimeofday()`	Returns the current time
`gmdate()`	Formats a GMT/UTC date and time
`gmmktime()`	Returns 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 integer
`localtime()`	Returns the local time
`microtime()`	Returns the current Unix timestamp with microseconds
`mktime()`	Returns 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()`	Parses an English textual datetime into a Unix timestamp
`time()`	Returns the current time as a Unix timestamp
`timezone_abbreviations_list()`	Returns an associative array containing dst, offset, and the timezone name
`timezone_identifiers_list()`	Returns an indexed array with all timezone identifiers
`timezone_location_get()`	Returns location information for a specified timezone
`timezone_name_from_ abbr()`	Returns the timezone name from abbreviation
`timezone_name_get()`	Returns the name of the timezone
`timezone_offset_get()`	Returns the timezone offset from GMT
`timezone_open()`	Creates new DateTimeZone object
`timezone_transitions_get()`	Returns all transitions for the timezone
`timezone_version_get()`	Returns the version of the timezonedb

Filter Function

Function	Description
`filter_has_var()`	Checks whether a variable of a specified input type exist
`filter_id()`	Returns the filter ID of a specified filter name
`filter_input()`	Gets an external variable (e.g. from form input) and optionally filters it
`filter_input_array()`	Gets external variables (e.g. from form input) and optionally filters them
`filter_list()`	Returns a list of all supported filter names
`filter_var()`	Filters a variable with a specified filter
`filter_var_array()`	Gets multiple variables and filter them

MySQLi Function

Function	Description
`affected_rows()`	Returns the number of affected rows in the previous MySQL operation
`autocommit()`	Turns on or off auto-committing database modifications
`begin_transaction()`	Starts a transaction
`change_user()`	Changes the user of the specified database connection
`character_set_name()`	Returns the default character set for the database connection
`close()`	Closes a previously opened database connection
`commit()`	Commits the current transaction
`connect()`	Opens a new connection to the MySQL server
`connect_errno()`	Returns the error code from the last connection error
`connect_error()`	Returns the error description from the last connection error
`data_seek()`	Adjusts the result pointer to an arbitrary row in the result-set
`debug()`	Performs debugging operations
`dump_debug_info()`	Dumps debugging info into the log
`errno()`	Returns the last error code for the most recent function call
`error()`	Returns the last error description for the most recent function call
`error_list()`	Returns a list of errors for the most recent function call
`fetch_all()`	Fetches all result rows as an associative array, a numeric array, or both
`fetch_array()`	Fetches a result row as an associative, a numeric array, or both
`fetch_assoc()`	Fetches a result row as an associative array
`fetch_field()`	Returns the next field in the result-set, as an object
`fetch_field_direct()`	Returns meta-data for a single field in the result-set, as an object
`fetch_fields()`	Returns an array of objects that represent the fields in a result-set
`fetch_lengths()`	Returns the lengths of the columns of the current row in the result-set
`fetch_object()`	Returns the current row of a result-set, as an object
`fetch_row()`	Fetches one row from a result-set and returns it as an enumerated array
`field_count()`	Returns the number of columns for the most recent query
`field_seek()`	Sets the field cursor to the given field offset
`info()`	Returns information about the last executed query
`init()`	Initializes MySQLi and returns a resource for use with real_connect()
`insert_id()`	Returns the auto-generated id from the last query
`kill()`	Asks the server to kill a MySQL thread
`more_results()`	Checks if there are more results from a multi query
`multi_query()`	Performs one or more queries on the database
`next_result()`	Prepares the next result-set from multi_query()
`options()`	Sets extra connect options and affect behavior for a connection
`ping()`	Pings a server connection, or tries to reconnect if the connection has gone down
`poll()`	Polls connections
`prepare()`	Prepares an SQL statement for execution
`query()`	Performs a query against a database
`real_connect()`	Opens a new connection to the MySQL server
`real_escape_string()`	Escapes special characters in a string for use in an SQL statement
`real_query()`	Executes a single SQL query
`reap_async_query()`	Returns result from an async SQL query
`refresh()`	Refreshes/flushes tables or caches, or resets the replication server information
`rollback()`	Rolls back the current transaction for the database
`select_db()`	Select the default database for database queries
`set_charset()`	Sets the default client character set
`set_local_infile_default()`	Unsets user defined handler for load local infile command
`set_local_infile_handler()`	Set callback function for LOAD DATA LOCAL INFILE command
`sqlstate()`	Returns the SQLSTATE error code for the error
`ssl_set()`	Used to establish secure connections using SSL
`stat()`	Returns the current system status
`stmt_init()`	Initializes a statement and returns an object for use with stmt_prepare()
`store_result()`	Transfers a result-set from the last query
`thread_id()`	Returns the thread ID for the current connection
`thread_safe()`	Returns whether the client library is compiled as thread-safe
`use_result()`	Initiates the retrieval of a result-set from the last query executed
`warning_count()`	Returns the number of warnings from the last query in the connection

PHP Regular Expression Functions

Function	Description
`preg_filter()`	Returns a string or an array with pattern matches replaced, but only if matches were found
`preg_grep()`	Returns an array consisting only of elements from the input array which matched the pattern
`preg_last_error()`	Returns an error code indicating the reason that the most recent regular expression call failed
`preg_match()`	Finds the first match of a pattern in a string
`preg_match_all()`	Finds all matches of a pattern in a string
`preg_replace()`	Returns a string where matches of a pattern (or an array of patterns) are replaced with a substring (or an array of substrings) in a given string
`preg_replace_callback()`	Given an expression and a callback, returns a string where all matches of the expression are replaced with the substring returned by the callback
`preg_replace_callback_array()`	Given an array associating expressions with callbacks, returns a string where all matches of each expression are replaced with the substring returned by the callback
`preg_split()`	Breaks a string into an array using matches of a regular expression as separators
`preg_quote()`	Escapes characters that have a special meaning in regular expressions by putting a backslash in front of them

Escape Sequence​

Operators​

Arithmetic Operators​

Comparison Operators​

Logical Operators​

String Operators​

Array Operators​

Conditional Assignment Operators​

Increment/Decrement Operators​

Super global variable​

Important keywords $_SERVER​

Functions​

Array Function​

PHP standard functions​

String function​

File function​

Read File​

Cookies and Session​

Most Important Function​

calender function​

Date/time Function​

Filter Function​

MySQLi Function​

PHP Regular Expression Functions​

Escape Sequence

Operators

Arithmetic Operators

Comparison Operators

Logical Operators

String Operators

Array Operators

Conditional Assignment Operators

Increment/Decrement Operators

Super global variable

Important keywords $_SERVER

Functions

Array Function

PHP standard functions

String function

File function

Read File

Cookies and Session

Most Important Function

calender function

Date/time Function

Filter Function

MySQLi Function

PHP Regular Expression Functions