A PHP cheat sheet (reference page)

PHP cheat sheet FAQ: Can you share a PHP cheat sheet?

This page is a PHP cheat sheet, but a different kind of cheat sheet. As I go deeper and deeper down the PHP rabbit hole, I found that instead of an over-simplified PHP cheat sheet, I wanted a "starter" page that will point me in the right direction when I'm looking for a PHP function for a task. For instance, if I can't remember how to add an element to a PHP array, I want to be able to search this page and find that easily.

I'm also adding links to this page, so I can find even more things very easily. For instance, working with arrays in PHP is a big deal, so I've added a link to a main PHP arrays reference page.

Given that brief introduction, here is my PHP cheat sheet (reference page).

PHP if/else syntax (elseif)

Here are a few examples of correct PHP if/else syntax.

if ($a > $b) 
{
  echo "a is bigger than b";
}
elseif ($a == $b)
{
  echo "a is equal to b";
}
else
{
  echo "a is smaller than b";
}

You can also use this PHP if/elsif syntax:

if($a > $b):
  echo $a." is greater than ".$b;
elseif($a == $b): // Note the combination of the words.
  echo $a." equals ".$b;
else:
  echo $a." is neither greater than or equal to ".$b;
endif;

These examples come from php.net/manual/en/control-structures.elseif.php

PHP for loop syntax (for loop, foreach loop)

Here is an example of the PHP for loop syntax.

# get the array length
$length = count($words);
for ($i=0; $i<$length; $i++)
{
  $words[$i] = strtolower($words[$i]);
}

Here is an example of the PHP foreach loop syntax.

foreach ($words as $word)
{
  echo "$word\n";
}

PHP arrays reference

http://www.php.net/manual/en/ref.array.php

array_merge (array1, array2, ...)

Merges the elements of one or more arrays together so that the values of one are appended to the end of the previous one. It returns the resulting array.

array_pop (array)

Pops and returns the last value of the array, shortening the array by one element. If array is empty (or is not an array), NULL will be returned.

array_push (array, $var)

Treats array as a stack, and pushes the passed variables onto the end of array. The length of array increases by the number of variables pushed.

array_rand (array)

Useful when you want to pick one or more random entries out of an array.

array_search (mixed $needle, array $haystack)

Searches haystack for needle.

array_diff

Compares array1 against array2 and returns the difference.

count

Counts all elements in an array, or properties in an object.

in_array (mixed $needle, array $haystack)

Searches haystack for needle.

key (array)

key() returns the index element of the current array position.

sort

Sorts an array. Elements will be arranged from lowest to highest when this function has completed.

PHP string functions

See this page for more information: http://www.php.net/manual/en/ref.strings.php

addslashes (string)

Returns a string with backslashes before characters that need to be quoted in database queries etc. These characters are single quote ('), double quote ("), backslash (\) and NUL (the NULL byte).

chop

An alias of rtrim. This is different than the Perl chop function.

crypt

One-way string hashing. return a hashed string using the standard Unix DES-based algorithm or alternative algorithms.

echo

Output one or more strings.

explode(string $delimiter, string $string, [, int $limit])

Spit a string into an array. Returns an array of strings, each of which is a substring of string formed by splitting it on boundaries formed by the string delimiter.

implode(string $glue, array $pieces), or implode(array $pieces)

Join array elements together into a string with a glue string. (Converts an array to a string.)

join

An alias of implode.

lcfirst ($str)

Returns a string with the first character of str converted to lowercase, if that character is alphabetic.

ltrim

Strip whitespace (or other characters) from the beginning of a string.

md5

Calculate the md5 hash of a string.

print

print() is not actually a real function (it is a language construct) so you are not required to use parentheses with its argument list.

printf

Print a formatted string.

rtrim

Returns a string with whitespace stripped from the end of str.

sscanf

The function sscanf() is the input analog of printf(). sscanf() reads from the string str and interprets it according to the specified format, which is described in the documentation for sprintf().

sprintf

Returns a string produced according to the formatting string format.

str_replace

This function returns a string or an array with all occurrences of search in subject replaced with the given replace value.

str_split

Converts a string to an array (returns an array).

stripos

Returns the numeric position of the first occurrence of needle in the haystack string.

stristr

Case-insensitive strstr(). Returns all of haystack from the first occurrence of needle to the end.

strstr

Find first occurrence of a string. Returns part of haystack string from the first occurrence of needle to the end of haystack.

strlen

Returns the length of the given string.

strtolower

Returns string with all alphabetic characters converted to lowercase.

strtoupper

Returns string with all alphabetic characters converted to uppercase.

substr

Return part of a string. Returns the portion of string specified by the start and length parameters.

substr_count(string $haystack, string $needle)

returns the number of times the needle substring occurs in the haystack string. Please note that needle is case sensitive.

substr_replace

replaces a copy of string delimited by the start and (optionally) length parameters with the string given in replacement.

trim

Strip whitespace (or other characters) from the beginning and end of a string

strpos ($haystack, $needle)

Returns the numeric position of the first occurrence of needle in the haystack string. Unlike the strrpos() before PHP 5, this function can take a full string as the needle parameter and the entire string will be used.

strip_tags

Strip HTML and PHP tags from a string

str_replace

Replace all occurrences of the search string with the replacement string. If you don't need fancy replacing rules (like regular expressions), you should always use this function instead of ereg_replace() or preg_replace().

ucfirst ($str)

Returns a string with the first character of $str capitalized (uppercase), if that character is alphabetic.

ucwords

Returns a string with the first character of each word in str capitalized, if that character is alphabetic.

PHP regex functions

See this page for Perl-style PHP regex functions: http://www.php.net/manual/en/ref.pcre.php
See this page for POSIX-style PHP regex functions: http://www.php.net/manual/en/ref.regex.php

ereg

This function has been DEPRECATED as of PHP 5.3.0.

eregi

This function has been DEPRECATED as of PHP 5.3.0.

ereg_replace

This function has been DEPRECATED as of PHP 5.3.0.

eregi_replace

This function has been DEPRECATED as of PHP 5.3.0.

split

This function has been DEPRECATED as of PHP 5.3.0.

spliti

This function has been DEPRECATED as of PHP 5.3.0.

preg_filter

Identical to preg_replace() except it only returns the matches.

preg_grep (pattern, array)

Return array entries that match the pattern. Returns the array consisting of the elements of the input array that match the given pattern.

preg_match (pattern, subject[, submatches])

Perform a regular expression match. Searches subject for a match to the regular expression given in pattern.

preg_quote

Quote regular expression characters. Takes str and puts a backslash in front of every character that is part of the regular expression syntax.

preg_replace (pattern, replacement, subject)

Perform a regular expression search and replace.

preg_split

Split the given string by a regular expression.

trim

This function returns a string with whitespace stripped from the beginning and end of str.

PHP date and time functions

date

Returns a string formatted according to the given format string using the given integer timestamp.

date_add

An alias of DateTime::add, allows the addition of day(s),month(s),year(s) to the original date.

date_format

Returns date formatted according to given format.

mktime

Returns the Unix timestamp corresponding to the arguments given.

strtotime

Parse about any English textual datetime description into a Unix timestamp.

time

Returns the current time measured in the number of seconds since the Unix Epoch.

PHP variable functions

empty

Determine whether a variable is empty.

is_array

Finds whether a variable is an array.

is_int

Find whether the type of a variable is integer.

is_null

Finds whether the given variable is NULL.

is_numeric

Finds whether a variable is a number or a numeric string.

is_object

Finds whether the given variable is an object.

is_scalar

Finds whether a variable is a scalar.

isset

Determine if a variable is set and is not NULL.

unset

Unset a given variable.

print_r

Prints human-readable information about a variable.

var_dump

Dumps information about a variable. Displays structured information about one or more expressions that includes its type and value. Arrays and objects are explored recursively with values indented to show structure.

PHP HTML programming functions

base64_decode

Decodes data encoded with MIME base64.

base64_encode

Encodes the given data with base64. This encoding is designed to make binary data survive transport through transport layers that are not 8-bit clean, such as mail bodies.

get_headers

Fetches all the headers sent by the server in response to a HTTP request. returns an array with the headers sent by the server in response to a HTTP request.

htmlentities

Convert all applicable characters to HTML entities.

mail

Sends an email. (http://us2.php.net/manual/en/function.mail.php)

parse_url

Parses a URL and returns an associative array containing any of the various components of the URL that are present.

rawurldecode

Returns a string in which the sequences with percent (%) signs followed by two hex digits have been replaced with literal characters.

rawurlencode

Returns a string in which all non-alphanumeric characters except -_. have been replaced with a percent (%) sign followed by two hex digits.

session_destroy

Destroys all data registered to a session.

session_get_cookie_params

Get the session cookie parameters (returns an array).

session_set_cookie_params

Set the session cookie parameters.

session_start

Creates a session or resumes the current one based on a session identifier passed via a GET or POST request, or passed via a cookie.

session_id

Get and/or set the current session id.

session_unset

Free all session variables.

setcookie

Defines a cookie to be sent along with the rest of the HTTP headers. Like other headers, cookies must be sent before any output from your script (this is a protocol restriction). This requires that you place calls to this function prior to any output, including and tags as well as any whitespace.

urldecode

Decodes any %## encoding in the given string. Plus symbols ('+') are decoded to a space character.

urlencode

URL-encodes string.

http://www.php.net/manual/en/reserved.variables.php

$_ENV

An associative array of variables passed to the current script via the environment method.

$_GET

An associative array of variables passed to the current script via the URL parameters.

$_POST

An associative array of variables passed to the current script via the HTTP POST method.

$_COOKIE

An associative array of variables passed to the current script via HTTP Cookies.

$_SESSION

An associative array containing session variables available to the current script.

$_SERVER

An array containing information such as headers, paths, and script locations.

$_REQUEST

An associative array that by default contains the contents of $_GET, $_POST and $_COOKIE.

$GLOBALS

An associative array containing references to all variables which are currently defined in the global scope of the script.

PHP number functions

http://us2.php.net/manual/en/ref.math.php

ceil

Returns the next highest integer value by rounding up value if necessary.

max

Finds the maximum value in an array, or in a series of parameters.

min

Finds the minimum value in an array, or in a series of parameters.

number_format

Format a number with grouped thousands.

rand

Generate a random number.

round

Rounds a float.

PHP files and filesystem functions

http://us2.php.net/manual/en/ref.filesystem.php

basename

Returns filename component of path.

copy

Makes a copy of the file source to dest.

delete

Use unlink() or unset().

fclose

Closes an open file pointer.

fgets

Gets line from file pointer.

file

Reads entire file into an array.

fopen

Opens file or URL.

fputs

Alias of fwrite().

fread

Binary-safe file read.

fwrite

Writes the contents of string to the file stream pointed to by handle.

is_dir

Tests whether the given filename is a directory.

is_file

Tests whether the given filename is a file.

parse_ini_file

Loads in the ini file (configuration file) specified in filename, and returns the settings in it in an associative array.

readfile

Reads a file and writes it to the output buffer.

PHP exec

exec

Execute an external program.

system

Execute an external program and display the output.

PHP network functions

fsockopen

Open Internet or Unix domain socket connection.

gethostbyaddr (string ip_address)

Get the Internet host name corresponding to a given IP address.

gethostbyname (string hostname)

Returns the IPv4 address of the Internet host specified by hostname.

gethostname

Gets the standard host name for the local machine.

PHP error reporting

Here's a link to the PHP error reporting page.

PHP PEAR Database Access with MDB2

• The main MDB2 database manual page.
• The MDB2 API pages.