PHP Reference

CAUTION: this page is a collection of notes and not verified reference material — rely on it at your own risk!

Arrays

$primes = array(2, 3, 5, 7, 11, 13);

echo $primes[0];

Creates an array of prime numbers

and returns 2 (the first element in the array)

$days = array('yesterday', 'today', 'tomorrow');

Creates an array of string values

$sudoku = array(array(9, 8, 5), array(2, 7, 3), array(1, 6, 4));

echo $sudoku[1][0];

Creates a two-dimensional array (an array of arrays)

and returns 2 (the first element in the second array)

$example[0] = "one";
$example[1] = "two";
$example[2] = "three";

$example[] = "one";
$example[] = "two";
$example[] = "three";

These two sets of statements have identical results since arrays can be populated without specifying an index and the elements will be indexed automatically as they are created

$prime_numbers = count($primes);

$rows = count($sudoku, 0);

$block = count($sudoku, 1);

The count() function returns the number of elements in an array
with an optional second argument to specific top-level-only (0)
or all elements and sub-elements (1)

$prices = array('12.95', '3.50', '29.99', '77', '7');

sort($prices);

rsort($prices);

This will re-arrange the elements in the array so that they are in order
(default sort order is alphabetical or numeric depending on content)

rsort() does the same thing but in reverse order [note: sort() modifies the original array and returns true, so to create a new array as a sorted version of the original you need to clone the array and sort the clone]

$prices = array('12.95', '3.50', '29.99', '77', '7');

sort($prices, SORT_NUMERIC);

rsort($prices, SORT_NUMERIC);

Option second argument forces the elements to be sorted as numbers
(so 3.50, 7, 12.95, 29.99, 77 would result, and vice versa)

$prices = array('12.95', '3.50', '29.99', '77', '7');

sort($prices, SORT_STRING);

rsort($prices, SORT_STRING);

Option second argument forces the elements to be sorted as strings
(so '12.95', '29.99', '3.50', '7', '77' would result, and vice versa)

$cards = array(1,2,3,4,5,6,7,8,9,10,11,12,13);

shuffle($cards);

This will re-arrange the elements in the array in random order (modifies the original array and returns true, so to create a new array as a shuffled version of the original you would clone the array and shuffle the clone)

$days = array(31,28,31,30,31,30,31,31,30,31,30,31);

$m_sizes = array_unique($days);

This will remove duplicate elements; only values in elements 0, 1 & 3
(the first instances of 31, 28 & 30) will be copied to the new array

$usa = array('New York', 'Washington');
$eur = array('London', 'Paris', 'Rome');

$cities = array_merge($eur, $usa);

This will copy all 5 elements to the new array with indexes 0 to 4

(with associative arrays that both contain elements with the same
keys, the first one copied will be replaced by the later one)

$first_element = reset($cards);

This will pull the first element of the array $cards
(in a foreach loop, goes back to the first element in the array)

$last_element = end($cards);

This will pull the last element of the array $cards
(in a foreach loop, goes ahead to the last element in the array)

if (is_array($primes))
   {
      echo 'Array Confirmed. Woohoo!';
   }

the is_array() function tests whether its argument is an array

$ankhy = array('gender' => "male", 'fur' => "striped", 'size' => "extra large");

echo $ankhy['fur'];

echo "<p> $ankhy[fur] </p>";

This is an associative array (in PHP, different from an object)

$ankhy['gender'] = "male";
$ankhy['fur'] = "striped";
$ankhy['size'] = "extra large";

This is the simple way to set up an associative array

extract($ankhy);

This creates a set of variables with names and values generated from the array, thus a variable $gender whose value is "male", etc.

extract($ankhy, EXTR_PREFIX_ALL, "cat");

This refines the extract function to prefix the variable names, thus the variables are $cat_gender, $cat_fur, etc.

$md_cap = "Annapolis";
$va_cap = "Richmond";
$ny_cap = "Albany";

$capitals = compact('md_cap', 'va_cap', 'ny_cap');

echo $capitals['md_cap'];

This creates an associative array from a specified set of variables

$c = compact(explode(' ', 'md_cap va_cap ny_cap'));

Shortcut for creating an array with compact()

$where = array('London', 'Rome', 'Nepal');
$when = array('2009', '2018', '2025');

$travels = array_combine($where, $when);

Creates an associative array consisting of [London] 2009 etc.

asort($ankhy);

arsort($ankhy);

asort() sorts the elements of an associative array by value
(resulting in: [size] extra large, [gender] male, [fur] striped)

arsort() does the same thing but in reverse order

ksort($ankhy);

krsort($ankhy);

ksort() sorts the elements of an associative array by named key
(resulting in: [fur] striped, [gender] male, [size] extra large)

krsort() does the same thing but in reverse order

print_r($ankhy);

Will display the elements of an array and their values

Cookies

$visit_mark = time();
$exp = mktime(0, 0, 0, 12, 31, 2030);
setcookie("visit_date", $visit_mark, $exp);

Sets a cookie named "visit_date" with a value equal to the current date and an expiration date of 12/31/30; replaces any existing "visit_date" cookie

Note that cookies must be set before the HTML tag

setcookie("visit_date", "none", time() - 86400);

Deletes the "visit_date" cookie by setting it to expire one day in the past (86400 seconds is one day)

$last_visit = $_COOKIE["visit_date"];

Reads the value of the "visit_date" cookie (it may be necessary to reload the page to read data that was not already set on a previous visit)

if (!isset($_COOKIE["visit_date"]))
// code to be run if there is no "visit_date" cookie

Tests for the (non) presence of the "visit_date" cookie

$how_many_in_the_jar = count($_COOKIE);

Returns a count of elements in the superglobal array of cookies
(a zero value can indicate that cookies are disabled in the browser)

Date and Time

🗝︎

$rightnow = time();

Returns seconds since midnight 1/1/70 (PHP's core unit of time)

$newyear = mktime(0, 0, 0, 1, 1, 2016);

$fiftieth = mktime(19, 30, 0, 10, 31, 2017);

Returns seconds since midnight 1/1/70 for a specified point
(12:00:00 am on 1/1/16 and 7:30:00 pm on 10/31/17)

echo date("l F jS, Y", $rightnow);

echo date("l F jS, Y", time());

echo date("l F jS, Y");

Displays date formatted as Tuesday November 29th, 2016

(the second parameter is optional and defaults to the current time)

echo date("g: i A");

Displays time formatted as 3:43 PM

echo "Day Formats: " . date("D l N w");

Displays day formatted as Sun Sunday 7 0 (N shows Monday to Sunday as 1 to 7 and w shows Sunday to Saturday as 0 to 6)

echo "Day of Month Formats: " . date("d j");

Displays day of month formatted as 08 and 8

echo "Month Formats: " . date("M F m n");

Displays month formatted as Apr April 04 4

echo "Year Formats: " . date("Y y");

Displays four-digit year and two-digit year

echo "Hour Formats: " . date("g h G H");

Displays 8 o'clock as 8 or 8, 08 or 08, 8 or 20, 08 or 20

echo "Minutes Format: " . date("i");

Displays on the hour as 00

echo "Seconds Format: " . date("s");

Displays on the minute as 00

echo "Place in Year Formats: " . date("z W");

Displays day of the year (0-365) and week of the year (01-52)

echo "Modifiers: " . date("S a A");

Displays day of month suffix th and 12-hour suffixes pm & PM

echo "Statistics: " . date("t L");

Displays number of days in the month and leap days in year (1 or 0)

date_default_timezone_set("America/New_York");

date_default_timezone_set("America/Chicago");
date_default_timezone_set("America/Denver");
date_default_timezone_set("America/Los_Angeles");
date_default_timezone_set("Europe/London");
date_default_timezone_set("Europe/Paris");
date_default_timezone_set("Europe/Rome");
date_default_timezone_set("Asia/Hong_Kong");
date_default_timezone_set("Asia/Seoul");
date_default_timezone_set("Asia/Tokyo");

Sets the time zone for which the date and time will be read

(Common zones shown; see 'php.net/manual/en/timezones.php' or 'w3schools.com/php/php_ref_timezones.asp' for others)

if (checkdate($month, $day, $year)
{
echo "$month/$day/$year is a valid date";
}

Validates calendar dates based on m, d, y values

$s_w_day = strtotime('May 4 2017');

$birthday = strtotime('tomorrow');

$party = strtotime('next Saturday');

$vacation = strtotime('+6 months')'

$otherholiday = strtotime('+180 days');

$meeting1 = strtotime('last Thursday');

$meeting2 = strtotime('+1 month 2 weeks', $meeting1);

Interprets a text description of a date or a time adjustment
and returns a timestamp that can be run through date() for display

Time adjustments are done on the element specified so '+10 years' will differ from '+3650 days' (and the results should be checked in any case)

The default base time is the current time and the preferred numerical date format is 2017-05-04 although it can read others

Delay and Divert

echo "password received";
sleep(3);
echo "password validated";

Pauses 3 seconds between outputting "received" and "validated"

[THE PAGE LOAD WILL BE DELAYED UNTIL SLEEP CONCLUDES]

echo "password received";
usleep(3500000);
echo "password validated";

Pauses 3 1/2 seconds between outputting "received" and "validated"

(1000000 microseconds—six zeroes—is one second)

time_sleep_until($alarm);

time_sleep_until(time() + 30);

Pauses until the point in time recorded as $alarm

Pauses until the current time plus 30 seconds

echo "<script>location = 'page.php';</script>";

echo "<script>location.replace('pg.php');</script>";

Instead of equivalent PHP location methods, just generate Javascript

Error Management

$f = fopen("info.txt", 'r') or die("<h3>FAIL!</h3>");

Outputs the message and stops the program (while blocking default warning message otherwise displayed when using a local/testing server)

function customError($e_type, $e_msg)
{
echo "<h3>FAIL!</h3>";
}

set_error_handler("customError");

echo $nonexistent_variable;

The message will be output for any error (while blocking default warning message otherwise displayed when using a local/testing server)

The message will be output for any error with the specifics conveyed by the arguments representing the error number, system-defined error message, file name, line number and an array of the active variables

function customError($e_type, $e_msg)
{
echo "<h3>$e_msg</h3>";
}

set_error_handler("customError");

if ($n == 100)
{
trigger_error("Look out below!");
}

The specified text will be output when the error is triggered

function supercustomError($e_type, $e_msg)
{
echo "<h3>$e_msg</h3>";
}

set_error_handler("supercustomError", E_USER_WARNING);

if ($n == 100)
{
trigger_error("Sky falling!", E_USER_WARNING);
}

The specified text will be output when triggered as a user warning

function supercustomError($e_type, $e_msg)
{
echo "<h3>$e_msg</h3>";
}

set_error_handler("supercustomError", E_USER_ERROR);

if ($n == 100)
{
trigger_error("Blue Screen O'Death!", E_USER_ERROR);
}

The specified text will be output when triggered as a user error
—and the program will be stopped

External Code Importation

include "signoff.php";

Pastes the code from the signoff.php file into the current file

include_once "signoff.php";

Pastes the code from the signoff.php file into the current file and
prevents the same code from being included again even if another
include or include_once command is encountered

require "signoff.php";

Pastes the code from the signoff.php file into the current file
and prevents the program from continuing if the file is not found

require_once "signoff.php";

Pastes the code from the signoff.php file into the current file and
prevents the program from continuing if the file is not found and
prevents the same code from being included again even if another
require or require_once command is encountered

Form Handling

Passing data from a form using "get" (data shown in URL)

echo $_GET['city'];

extract($_GET, EXTR_PREFIX_ALL, 'via_get');

echo $via_get_city;

This method of extraction creates a set of variables prefixed with "via_get"—so if the the key/value pair "city:London" was sent over,
then $via_get_city would have the value "London" and so on

Passing data from a form using "post" (data hidden)

echo $_POST['name'];

extract($_POST, EXTR_PREFIX_ALL, 'via_post');

echo $via_post_name;

This method of extraction creates a set of variables prefixed with "via_post"—so if the the key/value pair "name:Oscar" was sent over, then $via_post_name would have the value "Oscar" and so on

<form id=r action=<<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?> method=post>

Posts (or, alternately, gets) data for processing to the same page it is
being sent from without actually knowing the page name;
htmlspecialchars() is used to remove HTML tags for security

...<input type=submit name=login />...

...<input type=submit name=register />...

<?php
if ($_GET) { // code for processing data }
if ($_POST) { // code for processing data }
if ($_SERVER['REQUEST_METHOD'] == "GET") { // code }
if ($_SERVER['REQUEST_METHOD'] == "POST") { // code }
if ($_POST['login']) { // code for processing data }
?>

The associated code runs when:

The global variable which holds data sent by 'GET' has value
The global variable which holds data sent by 'POST' has value
Data has been sent by the 'GET' method
Data has been sent by the 'POST' method
The button named 'login' was pushed

$_REQUEST

This predefined global array contains info from all methods
(i.e., everything that's in either $_GET or $_POST)

<?php
$name_error = "";
if ($_POST['register']))
{
   if (empty($_POST['name']))
   {
      $name_error = "Name Required!";
   }
} else // code for processing data
?>

<form id=r action=register.php method=post>
<label>Name: <input type=text name=name required= required /> <?php echo $name_error; ?> </label>
<input type=submit name="register" />
</form>

Generating an error message when a field is skipped

<?php
$email_error = "";
if ($_POST['register']))
{
   $email = $_POST['email'];
   if (!filter_var($email, FILTER_VALIDATE_EMAIL))
   {
      $email_error = "Invalid email address!";
   }
} else // code for processing data
?>

<form id=r action=register.php method=post>
<label>Name: <input type=text name=email required= required /> <?php echo $email_error; ?> </label>
<input type=submit name="register" />
</form>

There is a preset filter for validating email

if (!filter_var($x, FILTER_VALIDATE_INT) === false)

There is a preset filter for validating integers (except 0)

if (!filter_var($x, FILTER_VALIDATE_FLOAT) === false)

There is a preset filter for validating floating point numbers

$n = filter_var($x, FILTER_SANITIZE_NUMBER_INT);

$n = filter_var($x, FILTER_SANITIZE_NUMBER_FLOAT);

There are filters to clean up numbers which have extraneous characters

<?php
$user_name = "";
if ($_POST['register']))
{
$user_name = $_POST['name'];
// code for processing data
}
?>

<form id=r action=register.php method=post>
<label>Name: <input type=text name=name required= required value="<?php echo $user_name; ?>" /> </label>
<input type=submit name="register" />
</form>

The submitted data can be retained in the fields in which it was entered

<?php
$pref_day = "";
if ($_POST['register']))
{
$pref_day = $_POST['day'];
// code for processing data
}
?>

<form id=r action=register.php method=post>
<label>Preferred Day: <select name=day size=1> <option <?php if ($pref_day == "Sunday") echo "selected"; ?>>Sunday</option>
</select></label>
<input type=submit name="register" />
</form>

Data retention for option selection menus

<?php
$when = "";
if ($_POST['register']))
{
$when = $_POST['when'];
// code for processing data
}
?>

<form id=r action=register.php method=post>
<label><imput type="radio" name=when value="afnoon" <?php if ($when) == "afnoon") echo "checked"; ?> /> Afternoon</label>
<input type=submit name="register" />
</form>

Data retention for radio buttons

<?php
$newsletter = "on";
if ($_POST['register']))
{
$newsletter = $_POST['newsletter'];
// code for processing data
}
?>

<form id=r action=register.php method=post>
<label><imput type="checkbox" name=newsletter <?php if (!isset($newsletter) || $newsletter == "on") echo "checked"; ?> /> Get Our Newsletter!</label>
<input type=submit name="register" />
</form>

Data retention for (preselected) checkboxes

Files can be uploaded via post using a form like this

$p = "images/newpicture.jpg";
move_uploaded_file($_FILES['pic']['tmp_name'], $p);

Stores the uploaded file as images/newpicture.jpg

$filetype = $_FILES["pic"]["type"];

Possible values for image files include image/jpeg, image/gif, image/png, image/tiff also see finfo_open

$filesize = $_FILES["pic"]["size"];

Returns the file size in bytes (e.g. 15000 is 15KB)

$uploadcheck = $_FILES["pic"]["error"];

No error (0) is UPLOAD_ERR_OK

$originalfilename = basename($_FILES["pic"]["name"]);

Returns the given name of the file that was uploaded

Functions

function square($y)
{
return $y * $y;
}

Will multiply the value sent to it times itself and return that result to the place where the function was invoked

$x = square($a);

Calls function square and sets the value of $x as the result of doing the function's calculations on $a

function expoMe($x)
{
   $s1 = $x * $x;
   $s2 = $x * $x *$x;
   $s3 = $x * $x * $x * $x;
   return array($x,$s1,$s2,$s3);
}

A function can be set up to return data in the form of an array

function schedule($h = 10)
{
return $h . " o'clock tomorrow";
}

This function can be called without an argument and the specified default value 10 will be used as though it had been passed as the argument

function describe_cat($value, $key_text, $x)
{
   echo "<p style='font-size:" . $x . "em;'>";
   echo "The cat's $key_text is $value.";
   echo "</p>";
}

array_walk($ankhy, "describe_cat", 2);

A function can be called on all the elements of an array with array_walk()

[$key_text and $value arguments are read from the array; the additional argument $x is passed as an optional argument of array_walk()]

Loops and Conditionals

if ($x == 10)
   {
      $y = "decade";
   }

If the value of $x is 10, set the value of $y to "decade"

if ($x == 10)
   {
      $y = "decade";
   } else
      {
         $y = "year";
      }

If the value of $x is 10, set the value of $y to "decade"

—otherwise, set the value of $y to "year"

$x == 10 ? $y = "decade" : $y = "year";

If the value of $x is 10, set the value of $y to "decade"

—otherwise, set the value of $y to "year"

$elder = $age >= 100 ? "centenarian" : "senior";

If the value of $age is 100 or more, set the value of $elder to

"centenarian"—otherwise, set the value to "senior"

if ($x == 10)
   {
      $y = "decade";
   } elseif ($x == 100)
      {
         $y = "century";
      }

If the value of $x is 10, set the value of $y to "decade"

—otherwise, if $x is 100 set the value of $y to "century"

(either else if or elseif will work)

for ($a = 10; $a <= 50; $a +=10)
   {
      echo $a . " ";
   }

10 20 30 40 50

for ($a = 10, $b = 50; $a <= 50; $a +=10, $b -=10)
   {
      echo $a . " " . b . "<br />";
   }

10 50
20 40
30 30
40 20
50 10

switch ($callSign)
{
   case "A":
   echo "<h4>Alpha</h4>";
   break;
   case "B":
   echo "<h4>Bravo</h4>";
   break;
   case "C":
   echo "<h4>Charlie</h4>";
   break;
   default:
   echo "<h4>INVALID SIGN</h4>";
}

Will print "Alpha" if $callSign equals "A", etc.

$a = 10;
while ($a <= 50)
   {
      echo $a . " ";
      $a +=10;
   }

10 20 30 40 50

$a = 10;
do
   {
      echo $a . " ";
      $a +=10;
   } while ($a <= 50);

10 20 30 40 50

$primes = array(2, 3, 5, 7, 11, 13);

foreach($primes as $number)
   {
      echo "One prime number is $number <br />";
   }

The foreach...as loop will automatically loop through an array
(this is the syntax for a numerically indexed array)

$ankhy = array('gender' => "male", 'fur' => "striped", 'size' => "extra large");

foreach($ankhy as $trait => $descrip)
   {
      echo "The cat's $trait is $descrip <br />";
   }

The foreach...as loop will automatically loop through an array
(this is the syntax for an associative array)

break;

break 2;

When executed in the {body} of a loop or switch statement, will discontinue the loop and move on to the next statement after the loop (most commonly used in a switch statement to stop after one case)
—can also specify the number of levels to break through

continue;

When executed in the {body} of a loop, it bypasses the rest of the statements in the body and re-iterates the loop

Math and Number Manipulation

$x = rand(1, 12);

$x = mt_rand(1, 12);

Sets $x to a random integer from 1 to 12

Also sets $x to a random integer from 1 to 12; works better
because it uses an algorithm with an interesting name

$gap = abs(8 - 12);

Sets $gap to 4 whether the expression value is 4 or -4

$x = min($a, $b, $c);

$y = max($a, $b, $c);

Sets $x to the smallest value in the list (of at least two, or an array)

Sets $y to the largest value in the list (of at least two, or an array)

if (is_nan($entry)) echo "Can't count to $entry!";

Validates (by returning 1) if $entry is NOT a number

echo "The hex value of $x is " . dechex($x) . "!";

Converts a decimal value to the hexadecimal version (as a string)

echo "The decimal value of $x is " . hexdec($x) . "!";

Converts a hexadecimal (string) to the decimal format number

printf("<p>A hundred can be the decimal integer %d, the unsigned decimal %u, the floating point decimal %f, the scientific notation %e, the binary %b and the octal %o. </p>", 100, 100, 100, 100, 100, 100);

Using various formatting characters, printf will convert standard decimal values into other formats (all of them are also usable with sprintf)

printf("<p>A hundred in hex is %x.</p>", 100);

$hundroid = sprintf("%x", 100);

Outputs the value in lowercase hexadecimal

(printf outputs to the browser while sprintf returns for assignment)

printf("<p style='color:#%X%X%X'>K</p>", 66, 77, 88);

printf("<p style='color:#%X%X%X'>Other numeric expressions are valid</p>", 200, $x, $y * 1.2);

Outputs the values represented by %X in uppercase hexadecimal

printf("<p>Per diem is $%.2f.</p>", $allowance / 7);

Outputs the value as a 2-decimal-place floating point number

printf("<p>Amount: $%6f.</p>", 75 / 8);

Outputs the value in a 6 character field [ 9.375] (NEEDS <pre> TAGS)

printf("<p>Amount: $%6.2f.</p>", 75 / 8);

Outputs the value as 6 characters, 2 decimal places [ 9.38] "

printf("<p>Amount: $%06.2f.</p>", 75 / 8);

Outputs the value as 0-padded 6 characters, 2 decimal places [0009.38]

printf("<p>Amount: $%'*6.2f.</p>", 75 / 8);

Outputs the value as *-padded 6 characters, 2 decimal places [***9.38]

printf("<p>There are %s bottles of beer...</p>", 99);

Outputs the value represented by %s as a string

$phone = sprintf("%s - %s", 625, 1190);

Outputs the values represented by %s as strings

$x = number_format("1234");

$x = number_format("1234", 2);

$x = number_format("1234", 2, "*", "^");

Sets $x to 1,234 (will round off to an integer)

Sets $x to 1,234.00 (displays the specified number of decimal places)

Sets $x to 1^234*00 (first character is used as decimal point)

MySQL Controls

$targetserver = localhost;
$user = root;
$password = ;
$mc = new MySQLi($targetserver, $user, $password);

if ($mc->connect_error)
   {
      echo "Connection to SQL server failed.";
   } else echo "Connection to SQL server established.";

$sqlcommand = "CREATE DATABASE ships";

if ($mc->query($sqlcommand) === TRUE)
   {
      echo "Database has been created.";
   } else echo "Database creation failed.";

$mc->close();

Open a connection to the SQL server

Check for errors

Create a database to hold tables of information

And close the connection when finished

$targetserver = localhost;
$user = root;
$password = ;
$db = ships;
$mc = new MySQLi($targetserver, $user, $password, $db);

if ($mc->connect_error)
   {
      echo "Connection to SQL server failed.";
   } else echo "Connection to SQL server established.";

$sqlcommand = "CREATE TABLE baltimore (regnum INT(6) UNSIGNED AUTO INCREMENT PRIMARY KEY, name VARCHAR(25) NOT NULL, tonnage FLOAT, regdate TIMESTAMP)";

if ($mc->query($sqlcommand) === TRUE)
   {
      echo "Table has been created.";
   } else echo "Table creation failed.";

$sqlcommand = "INSERT INTO baltimore (name, tonnage) VALUES ('Grey Ghost', 42.7)";

if ($mc->query($sqlcommand) === TRUE)
   {
      $entrynum = $mc->insert_id;
      echo "Data entry #$entry_num has been added.";
   } else echo "Data entry failed.";

$sqlcommand = "DROP TABLE carthage";

if ($mc->query($sqlcommand) === TRUE)
   {
      echo "The table has been deleted.";
   } else echo "Table deletion failed.";

$mc->close();

Open a connection to a database on the SQL server

Check for errors

Create a table with defined fields to hold information

Add data to the table

Delete a table that is no longer needed

And close the connection when finished

$targetserver = localhost;
$user = root;
$password = ;
$db = inventory;
$mc = new MySQLi($targetserver, $user, $password, $db);

if ($mc->connect_error)
   {
      echo "Connection to SQL server failed.";
   } else echo "Connection to SQL server established.";

$a = $mc->prepare("INSERT INTO cars (make, model, year) VALUES (?, ?, ?)");

$a->bind_param("ssi", $make, $model, $year);

$make = "Pontiac";
$model = "Fiero";
$year = 1985;
$a->execute();

$a->close();

$mc->close();

Open a connection to a database on the SQL server

Check for errors

Set up a prepared statement to data to a table
("ssi" means "string string integer"; can also use double and blob)

Invoke the prepared statement with the data to add

Close the prepared statement

And close the connection when finished

// code to open a database connection called $mc

$sqlcommand = "SELECT name, t FROM boston";

$table_data = $mc->query($sqlcommand);

if ($table_data->num_rows > 0)
   {
      while ($row = $table_data->fetch_assoc())
      {
         echo $row['name'] . ":" . $row['t'] . " tons";
      }
   } else echo "No data was found";

// code to close the database connection called $mc

Select the data to be pulled from the table

Loop through each row of the data

$sqlcommand = "UPDATE ny SET t = 42 WHERE name = 'X'";

$sqlcommand = "DELETE FROM miami WHERE name = 'Jade'";

$sqlcommand = "SELECT * FROM boston LIMIT 3";

$sqlcommand = "SELECT * FROM boston LIMIT 3 OFFSET 3";

Change the data on an existing row

Delete an existing row entirely

Get only the first 3 rows from the table

Skip three rows and then get the next 3 rows

Note: Full MySQL Query syntax is on the MySQL page

Objects

echo "The car is a $car_1->model by $car_1->make";

Basic syntax for referring to a property of an object

$car_1->reminder();

Basic syntax for calling a method of an object

class Car
{
   function Car($c1, $c2)
   {
      $this->make = $c1;
      $this->model = $c2;
      $this->registered = "Maryland";
   }
   function reminder()
   {
      echo "Wash the $this->model!";
   }
}

Class declaration to provide the structure to create an object

[constructor function can be named "__construct" or the class name]

$c_make = "Pontiac";

$c_model = "Fiero";

$car_1 = new Car($c_make, $c_model);

Basic syntax for creating an object (as an instance of a class)

[the actual values can also be passed as arguments]

$car_2 = clone $car_1;

$car_2->model = "Solstice";

Create a separate copy of an object without affecting the original
(an object's value is passed by reference so the new one would otherwise just behave as a second name for the same object)

class Car
{
   function Car($c1, $c2)
   {
      $this->make = $c1;
      $this->model = $c2;
      $this->registered = "Maryland";
   }
   static function reminder()
   {
      echo "Wash the car!";
   }
}

Class declaration that includes a method for the class, not for its objects

Car::reminder();

Basic syntax for calling a method of a class

class Bike extends Car
{
public $engine, $surface;
}

Create a subclass that is a copy of the original plus any additions

class Bike extends Car
{
   public $engine, $surface;

   function reminder()
   {
      echo "Watch out for rain!";
   }
   function alt_reminder()
   {
      parent::reminder();
   }
}

Conflicts between identical names used in original and subclasses are resolved with parent:: and self:: (also applies to properties)

class Painting
{
   public $title;

   protected $curator;

   private $price;

   const MUSEUM = "The Froink Collection";

   static function creditline()
   {
      echo 'Courtesy of ' . self::MUSEUM;
   }
}

A public property is accessible to all code (default status)

A protected property is only accessible within a class or its subclasses

A private property is only accessible within the original class

A constant is defined within a class using const...

...and accessed using self::

class Boat
{
   static $count;

   function log_boat()
   {
      self::$count +=1;
      return self::$count;
   }
}

$jade = new Boat();

$jade->log_boat();

$bc = Boat::$count;

Includes a property for the class itself that can be accessed indirectly by its objects through a function as well as directly through the class name

class Car
{
   function __construct($c1, $c2)
   {
      $this->make = $c1;
      $this->model = $c2;
      $this->registered = "Maryland";
   }
   final function reminder()
   {
      echo "Be Safe!";
   }
}

A final method will not be overridden by a subclass method

class Car
{
   function __construct($c1, $c2)
   {
      $this->make = $c1;
      $this->model = $c2;
      $this->registered = "Maryland";
   }
   function __destruct()
   {
      echo "Goodbye!";
   }
}

A destructor method will run when the object is destroyed (deleted)

print_r($car_1);

Will display the properties of an object and their values

Operators

+ [e.g. $x = $n + 1;]

Sums the values of two numbers

. [e.g. $greeting = "Hello " . $name;]

Concatenates two strings (numbers will convert to strings)

$x +=$y;

Shortcut equivalent to $x = $x + $y;

$x .=$y;

Shortcut equivalent to $x = $x . $y;

- * / %
++ --
= -= *= /= %=
== != > < >= <=

These all work the same as in Javascript

=== !==

These are identity instead of strict equality comparison operators;
no type conversion so 1000 won't match "1000", nor will 1 match true

&& [e.g. $x == 0 && $y > 100]

Works the same as in Javascript

and [e.g. $x == 0 and $y > 100]

An alternate version of && with lower precedence

|| [e.g. $x == 0 || $x > 100]

Works the same as in Javascript

or [e.g. $x == 0 or $x > 100]

An alternate version of || with lower precedence

xor [e.g. $x == 0 xor $y == 100]

exclusive or — true if either but not both are true

Pattern Matching

if (preg_match("/[0-9]/", $digit))
{
echo "Verified numerical!";
}

Returns true if the argument is a numerical character

if (preg_match("/[a-zA-Z]/", $letter))
{
echo "Verified alphabetical!";
}

Returns true if the argument is a letter

if (preg_match("/[.,:;@- ]/", $other))
{
echo "Verified space or other interrupty thing!";
}

Returns true if the argument is a space or hyphen etc.

Session Variables

<?php
session_start();
?>
<!DOCTYPE html>

Opens a session so that session variables can be used

Note: sessions must be opened before the DOCTYPE declaration

$_SESSION["comments"] = "on";

Creates (or updates) a session variable called "comments"

if($_SESSION["comments"])
{
$comment_status = $_SESSION["comments"];
} else $comment_status = "off";

Accesses a session variable called "comments"

session_unset();

Destroys all the session variables (also go away when browser is closed)

session_destroy();

Destroys the session itself (also goes away when browser is closed)

Strings

$s = 'The variable $mud says \'sling me\'...';

This is a literal string: except for the \' used to include a single-quote mark without closing the string, it will set the value of $s to the exact characters that are between the single quotation marks

$s = "The pumpkin said $mud to the trebuchet...";

This string in double-quotes will interpret variables so if $mud is sling me then $s will be The pumpkin said sling me to the trebuchet...

\' \\

Escape characters which work in literal strings

\t \n \r

Escape characters for tab, new line and return which work in strings

$section1 = <<<_HEADLINE
<h1 id="breaking">$masthead</h1>
<h2>$subhead</h2>
<h4>$byline</h4>
_HEADLINE;

This is a heredoc, which is a multiline string format that allows for quotation marks and line breaks but can interpret variables

$banner = strtoupper("Festival!");

Sets $banner to FESTIVAL!

$banner = strtolower("E. E. Cummings");

Sets $banner to e. e. cummings

$banner = ucfirst("this is a text message");

Sets $banner to This is a text message

$banner = ucfirst(strtolower("HILL"));

Sets $banner to Hill [ucfirst() modifies result of strtolower()]

$banner = str_repeat("* ", 20);

Sets $banner to * * * * * * * * * * * * * * * * * * * * (20 * s)

$banner = strrev("icniV ad odranoeL ma I");

Sets $banner to I am Leonardo da Vinci

$x = strlen($log_entry);

Sets $x to the number of characters in $log_entry

$x = strpos($log_entry, "snow");

Sets $x to the position where "snow" first appears in $log_entry

$x = strrpos($log_entry, "snow");

Sets $x to the position where snow last appears in $log_entry

$spring = str_replace("snow", "rain", $log_entry);

Changes the word snow to rain in new version of $log_entry

$creed = "Not all those who wander are lost";

$c1 = substr($creed, 8)

$c2 = substr($creed, -8)

$c3 = substr($creed, 4, 3)

$c4 = substr($creed, 0, -8)

[characters are numbered beginning with 0, so #8 is the 9th]

Sets $c1 to the section of the string from the 9th character forward

Sets $c2 to the last 8 characters of the string

Sets $c3 to the 3 characters of the string from the 5th forward

Sets $c4 to the portion of the string from the 1st to the 9th from the end

$creed = "Not all those who wander are lost";

$words = explode(' ', $creed);

Creates an array $words with elements whose values are "Not", "all", etc.

$creed = "Not all those who wander are lost";

$letters = str_split($creed, 1);

Creates an array $letters with elements whose values are "N", "o", etc.

(1 is actually the default value but any length can be specified)

$r = trim($r);

$r = stripslashes($r);

$r = htmlspecialchars($r);

These are common methods for cleaning up data when processing forms

specifically, removing white space from the ends of a string, removing backslashes, and changing < > ' " and & to their character entities

printf("<p>ASCII character 55 is %c.</p>", 55);

$p = sprintf("ASCII character 55 is %c.", 55);

Outputs the ASCII character for the value represented by %c

(printf outputs to the browser while sprintf returns for assignment)

printf("<p>There are %s bottles of beer...</p>", 99);

Outputs the value represented by %s as a string

OTHER printf SPECIFICATIONS ARE UNDER MATH/NUMBERS

$phone = sprintf("%s - %s", 625, 1190);

Outputs the value represented by %s as a string

OTHER sprintf SPECIFICATIONS ARE UNDER MATH/NUMBERS

printf("<pre>«%15s»</pre>", $word);

Outputs the string to fill 15 spaces, padding on the left

printf("<pre>«%-15s»</pre>", $word);

Outputs the string to fill 15 spaces, padding on the right

printf("<pre>«%015s»</pre>", $word);

Outputs the string to fill 15 spaces, padded with 0's on the left

printf("<pre>«%'*15s»</pre>", $word);

Outputs the string to fill 15 spaces, padded with *'s on the left

printf("<pre>«%15.12s»</pre>", $word);

Outputs the first 12 characters to fill 15 spaces, padding on the left

Structural Basics

<?php
all the PHP code goes here
?>

Code within these tags will be processed as PHP

statements end with;

Semi-colon marks the end of a statement

// just a comment

A single-line comment

/* just a comment
that keeps going */

A multi-line comment

echo <h1>Hello $world</h1>;

Sends something through to the browser

print <h1>Hello $world</h1>;

Alternative to echo that can be used in complex expressions

http://localhost/filename.php

This is the address for internally stored pages

System & Program Info

phpinfo();

This is a component of PHP that provides an extensively detailed display of the user's PHP installation specs (already styled & formatted)

NEVER LEAVE A phpinfo() CALL ONLINE AS IT IS A SECURITY RISK

echo phpversion();

This predefined function provides the version of PHP currently running

echo $_SERVER['SERVER_SOFTWARE'];

This predefined global provides the type of server (e.g. Apache)

if (function_exists("array_combine"))
{
echo "PHP is not too old!";
}

Checks if the version of PHP now running supports the specified function

echo 'The file directory is ' . __DIR__;

This predefined constant provides the file directory chain

echo 'The name of this document is ' . __FILE__;

This predefined constant provides the file name

echo 'The active function name is ' . __FUNCTION__;

This predefined constant provides the function name

echo 'Currently at line number ' . __LINE__;

This predefined constant provides the line number within the file

$via_link_at = $_SERVER['HTTP_REFERER'];

This predefined global provides the url of the site from which the user navigated to the page as part of an array of information from the server

$via = htmlentities($_SERVER['HTTP_REFERER']);

The predefined htmlentities() function changes potentially malicious code into HTML characters (e.g. <) for security reasons in case the predefined global has been hacked

$user_ip = $_SERVER['REMOTE_ADDR'];

This predefined global provides the user's IP address

$browser = $_SERVER['HTTP_USER_AGENT'];

This predefined global provides some browser details

if($_SERVER['HTTPS']) { // code goes here; }

Is true if site was accessed through a secure connection

Text Files

$mf = fopen("magic.txt", 'w') or die("FAIL!");

$mc = "rabbit";
fwrite($mf, $mc) or die("FAIL!");

fclose($mf);

Creates a text file named "magic.txt" (replacing any old "magic.txt" file)

and adds the string "rabbit" to it

and then closes the file

$mf = fopen("magic.txt", 'a') or die("FAIL!");

$mc = " cards";
fwrite($mf, $mc) or die("FAIL!");

fclose($mf);

adds the string " cards" to the "magic.txt" file

$mf = fopen("magic.txt", 'a') or die("FAIL!");

flock($mf, LOCK_EX);
$mc = " wand";
fwrite($mf, $mc) or die("FAIL!");
flock($mf, LOCK_UN);

fclose($mf);

locking and unlocking the file when updating it will prevent corruption

$mf = fopen("magicspells.txt", 'r') or die("FAIL!");

$mc1 = fgets($mf);

$mc2 = fgets($mf);

$mc3 = fread($mf, 1000);

fclose($mf);

sets $mc1 equal to line 1 of the "magicspells.txt" file

sets $mc2 equal to line 2 of the "magicspells.txt" file

sets $mc3 equal the rest of the "magicspells.txt" file
(as long as that's less than 1000 characters; close & reopen to start over)

$ms = filesize("magicspells.txt");

Gets the size of a file

$mf = fopen("magicspells.txt", 'r') or die("FAIL!");

fseek($mf, 25);

echo "Seeing <q>" . fread($mf, 10) . "<q>"

echo " and now at " . ftell($mf) . ".";

fclose($mf);

goes to element 25 of the text file

reads the next ten characters

and reads the position it's now at (35)

$mf = fopen("magicspells.txt", 'r') or die("FAIL!");

while (!feof($mf))
{
$mc_next = fgetc($mf);
}

fclose($mf);

reads the location of the last character of the text file

sets $mc_next equal to the next character of the text file

$mc = file_get_contents("magicspells.txt");

Gets the entire contents of a file (or web page) without fopen

$mc_plus = readfile("magicspells.txt");

Gets the entire contents of a file as one long string (no line breaks)
plus the size of the file, also without fopen

copy("magic.txt", "props.txt") or die("FAIL!");

Copies the "magic.txt" file as "props.txt"

rename("magic.txt", "magic.new") or die("FAIL!");

Renames the "magic.txt" file as "magic.new"

if (unlink("magic.txt")) echo "DELETED!";

Destroys the "magic.txt" file—by invoking unlink, even via 'if' or 'if (!'

if (file_exists("magic.txt")) echo "FOUND!";

Checks for the existence of a "magic.txt" file

Variables

$count = 0;

$name = Charlotte;

All variable names start with $
(no explicit declaration needed and types are fluid)

$cash = 25 * 80;

$c1 = substr($cash, 0, 1);

$tax = $c1 / 4;

A number can be treated as a string so this will return the first digit
(1 character starting at element 0) without type modification and then numerical calculations can be done on the returned character

$x = null;

A variable with no value has a value of null; equal but not identical to 0

define("COMPANY", "Boeing");

echo COMPANY . $status;

A constant variable is specifically defined and then cannot be changed

$a = 19;
$b = 27;
$c = 42;
function predict($x, $y)
{
$z = 85;
return "The winning numbers are $x and $z";
}

echo predict($a, $b);

Will produce "The winning numbers are 19 and 85"

The way variable scope works, the function can read $a and $b (under the identifiers $x & $y) but not $c since it's not a global variable like it would be in Javascript; $z does only exist inside the function as usual, though

$a = 19;
$b = 27;
global $C = 67;
function predict($x, $y)
{
global $Z = 73;
return "The winning numbers are $y $C and ";
}

echo predict($a, $b) . $Z;

Will produce "The winning numbers are 27 67 and 73"

To bypass default variable scope, variables can be specifically defined as global variables so both $C and $Z are accessible by all lines; a constant (created with 'define') would also be globally accessible—and a variable could be defined outside a function then declared as global inside one

(The function arguments are passed as before)

function countHits($x)
{
   static $macks = 0;
   $macks +=$x;
   return $macks;
}

The static variable $macks is only accessible inside the function (like a local variable) but it retains its value between function calls (like a global one)

$GLOBALS

echo $GLOBALS['x'];

This predefined global contains global variables

this is a way the variable $x could be accessed from within a function

var_dump($x);

Will show the type and value of the variable $x

PHP Language Reference

Arrays

Cookies

Date and Time

Delay and Divert

Error Management

External Code Importation

Form Handling

Functions

Loops and Conditionals

Math and Number Manipulation

MySQL Controls

Objects

Operators

Pattern Matching

Session Variables

Strings

Structural Basics

System & Program Info

Text Files

Variables