echo function is used to display or print output
<?php
echo "Hello World";
?>
This is a single-line comment
// Twinkle Twinkle Little Star
This is a single-line comment
# Chocolate dedo mujhe yaar
This is a multiline comment
/* Code With
Harry */
This function dumps information about one or more variables.
<?php var_dump(var1, var2, ...); ?>
Variables are "containers" for storing information.
<?php
$Title = "PHP Cheat Sheet By CodeWithHarry";
?>
Datatype is a type of data
A string is a sequence of characters, like "Hello world!".
<?php
$x = "Harry";
echo $x;
?>
An integer is a number without any decimal part.
<?php
$x = 1234;
var_dump($x);
?>
A float is a number with a decimal point or a number in exponential form.
<?php
$x = 1.2345;
var_dump($x);
?>
An array stores multiple values in one single variable
<?php
$names = array("Harry","Rohan","Shubham");
var_dump($names);
?>
A class is a template for objects
<?php
class Harry{
// code goes here...
}
?>
An object is an instance of the class.
<?php
class Bike {
public $color;
public $model;
public function __construct($color, $model) {
$this->color = $color;
$this->model = $model;
}
public function message() {
return "My bike is a " . $this->color . " " . $this->model . "!";
}
}
?>
Escape sequences are used for escaping a character during string parsing. They are also used for giving special meaning to represent line breaks, tabs, alerts, and more.
It adds a newline
<?php
echo "\n";
?>
It inserts a carriage return in the text at this point.
<?php
echo "\r";
?>
It gives a horizontal tab space
<?php
echo "\t";
?>
It gives a vertical tab space
<?php
echo "\v";
?>
It is used for escape characters
<?php
echo "\e";
?>
It is commonly used as page separators but now is also used as section separators.
<?php
echo "\f";
?>
It adds a backslash
<?php
echo "\\";
?>
Print the next character as a dollar, not as part of a variable
<?php
echo "\$";
?>
Print the next character as a single quote, not a string closer
<?php
echo "\'";
?>
Print the next character as a double quote, not a string closer
<?php
echo "\"";
?>
Operators are symbols that tell the compiler or interpreter to perform specific mathematical or logical manipulations. These are of several types.
Sum of $x and $y
$x + $y
Difference of $x and $y
$x - $y
Product of $x and $y
$x * $y
Quotient of $x and $y
$x / $y
The remainder of $x divided by $y
$x % $y
Result of raising $x to the $y'th power
$x ** $y
The left operand gets set to the value of the expression on the right
x = y
x += y (Equivalent to x = x + y)
x += y
x -= y (Equivalent to x = x - y)
x -= y
x *= y (Equivalent to x = x * y)
x *= y
x /= y (Equivalent to x = x / y)
x /= y
x %= y (Equivalent to x = x % y)
x %= y
Returns true if $x is equal to $y
$x == $y
Returns true if $x is equal to $y, and they are of the same type
$x === $y
Returns true if $x is not equal to $y
$x != $y
Returns true if $x is not equal to $y
$x <> $y
Returns true if $x is not equal to $y, or they are not of the same type
$x !== $y
Returns true if $x is greater than $y
$x > $y
Returns true if $x is less than $y
$x <= $y
Returns true if $x is greater than or equal to $y
$x >= $y
Returns true if $x is less than or equal to $y
$x <= $y
Increments $x by one, then returns $x
++$x
Returns $x, then increments $x by one
$x++
Decrements $x by one, then returns $x
--$x
Returns $x, then decrements $x by one
$x--
True if both $x and $y are true
$x and $y
True if either $x or $y is true
$x or $y
True if either $x or $y is true, but not both
$x xor $y
True if both $x and $y are true
$x && $y
True if either $x or $y is true
$x || $y
True if $x is not true
!$x
Concatenation of $txt1 and $txt2
$txt1 . $txt2
Appends $txt2 to $txt1
$txt1 .= $txt2
Union of $x and $y
$x + $y
Returns true if $x and $y have the same key/value pairs
$x == $y
Returns true if $x and $y have the same key/value pairs in the same order and of the same types
$x === $y
Returns true if $x is not equal to $y
$x != $y
Returns true if $x is not equal to $y
$x <> $y
Returns true if $x is not identical to $y
$x !== $y
Returns the value of $x. The value of $x is expr2 if expr1 = TRUE. The value of $x is expr3 if expr1 = FALSE
$x = expr1 ? expr2 : expr3
if statement checks the condition and if it is True, then the block of if statement executes; otherwise, control skips that block of code.
if (condition) {
// code to execute if condition is met
}
If the condition of the if block evaluates to True, then the if block executes; otherwise, the else block executes.
if (condition) {
// code to execute if condition is met
} else {
// code to execute if condition is not met
}
It executes different codes for more than two conditions.
if (condition) {
// code to execute if condition is met
} elseif (condition) {
// code to execute if this condition is met
} else {
// code to execute if none of the conditions are met
}
It allows a variable to be tested for equality against a list of values (cases).
switch (n) {
case x:
// code to execute if n=x;
break;
case y:
// code to execute if n=y;
break;
case z:
// code to execute if n=z;
break;
// add more cases as needed
default:
// code to execute if n is neither of the above;
}
It is used to iterate the statements several times. It is frequently used to traverse the data structures like the array and linked list.
for (starting counter value; ending counter value; increment by which to increase) {
// code to execute goes here
}
The foreach loop loops through a block of code for each element in an array.
foreach ($InsertYourArrayName as $value) {
// code to execute goes here
}
It iterates the block of code as long as a specified condition is True or vice versa.
while (condition that must apply) {
// code to execute goes here
}
This loop is very similar to the while loop with one difference, i.e., the body of the do-while loop is executed at least once even if the condition is False. It is an exit-controlled loop.
do {
// code to execute goes here;
} while (condition that must apply);
$GLOBALS is a PHP super global variable used to access global variables from anywhere in the PHP script.
<?php
$a = 10;
$b = 15;
function addition() {
$GLOBALS['c'] = $GLOBALS['a'] + $GLOBALS['b'];
}
addition();
echo $c;
?>
Returns the filename of the currently executing script. $_SERVER is a PHP super global variable which holds information about headers, paths, and script locations.
$_SERVER['PHP_SELF']
Returns the version of the Common Gateway Interface (CGI) the server is using
$_SERVER['GATEWAY_INTERFACE']
Returns the IP address of the host server
$_SERVER['SERVER_ADDR']
Returns the name of the host server (such as www.codewithharry.com)
$_SERVER['SERVER_NAME']
Returns the server identification string (such as Apache/2.2.24)
$_SERVER['SERVER_SOFTWARE']
Returns the name and revision of the information protocol (such as HTTP/1.1)
$_SERVER['SERVER_PROTOCOL']
Returns the request method used to access the page (such as POST)
$_SERVER['REQUEST_METHOD']
Returns the timestamp of the start of the request (such as 1377687496)
$_SERVER['REQUEST_TIME']
Returns the query string if the page is accessed via a query string
$_SERVER['QUERY_STRING']
Returns the Accept header from the current request
$_SERVER['HTTP_ACCEPT']
Returns the Accept_Charset header from the current request (such as utf-8,ISO-8859-1)
$_SERVER['HTTP_ACCEPT_CHARSET']
Returns the Host header from the current request
$_SERVER['HTTP_HOST']
Returns the complete URL of the current page (not reliable because not all user-agents support it)
$_SERVER['HTTP_REFERER']
Is the script queried through a secure HTTP protocol?
$_SERVER['HTTPS']
Returns the IP address from where the user is viewing the current page
$_SERVER['REMOTE_ADDR']
Returns the Hostname from where the user is viewing the current page
$_SERVER['REMOTE_HOST']
Returns the port being used on the user's machine to communicate with the web server
$_SERVER['REMOTE_PORT']
Returns the absolute pathname of the currently executing script
$_SERVER['SCRIPT_FILENAME']
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 someone@codewithharry.com)
$_SERVER['SERVER_ADMIN']
Returns the port on the server machine being used by the webserver for communication (such as 80)
$_SERVER['SERVER_PORT']
Returns the server version and virtual hostname which are added to server-generated pages
$_SERVER['SERVER_SIGNATURE']
Returns the file system based path to the current script
$_SERVER['PATH_TRANSLATED']
Returns the path of the current script
$_SERVER['SCRIPT_NAME']
Returns the URI of the current page
$_SERVER['SCRIPT_URI']
PHP $_GET is a PHP super global variable used to collect form data after submitting an HTML form with method="get".
<?php
echo "Hello" . $_GET['Example'] . " at " . $_GET['web'];
?>
PHP $_POST is a PHP super global variable used to collect form data after submitting an HTML form with method="post". $_POST is also widely used to pass variables.
<html>
<body>
<form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>">
Name: <input type="text" name="fname">
<input type="submit">
</form>
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
$name = $_POST['fname'];
if (empty($name)) {
echo "Please Enter your name";
} else {
echo $name;
}
}
?>
</body>
</html>
PHP $_REQUEST is a PHP super global variable used to collect data after submitting an HTML form.
<html>
<body>
<form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>">
Name: <input type="text" name="fname">
<input type="submit">
</form>
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
$name = $_REQUEST['fname'];
if (empty($name)) {
echo "Name is empty";
} else {
echo $name;
}
}
?>
</body>
</html>
Boolval is used to get the boolean value of a variable
<?php
echo '0: '.(boolval(0) ? 'true' : 'false')."\n";
echo '42: '.(boolval(42) ? 'true' : 'false')."\n";
echo '0.0: '.(boolval(0.0) ? 'true' : 'false')."\n";
echo '4.2: '.(boolval(4.2) ? 'true' : 'false')."\n";
echo '"" : '.(boolval("") ? 'true' : 'false')."\n";
echo '"string": '.(boolval("string") ? 'true' : 'false')."\n";
echo '"0": '.(boolval("0") ? 'true' : 'false')."\n";
echo '"1": '.(boolval("1") ? 'true' : 'false')."\n";
echo '[1, 2]: '.(boolval([1, 2]) ? 'true' : 'false')."\n";
echo '[]: '.(boolval([]) ? 'true' : 'false')."\n";
echo 'stdClass: '.(boolval(new stdClass) ? 'true' : 'false')."\n";
?>
It is used to check whether a variable is empty. It also checks whether the variable is set/declared:
<?php
$x = 0;
// True because $x is set
if (isset($x)) {
echo "Variable 'x' is set";
}
?>
It unsets variables.
<?php
$a = "Namaste world!";
echo "The value of 'a' before unset: " . $a ;
unset($a);
echo "The value of 'a' after unset: " . $a;
?>
debug_zval_dump is used to dump a string representation of an internal zval structure to output
<?php
$var1 = 'Hello';
$var1 .= ' World';
$var2 = $var1;
debug_zval_dump($var1);
?>
Empty is used to check whether a variable is empty or not.
<?php
$var = 0;
// Evaluates to true because $var is empty
if (empty($var)) {
echo '$var is either 0, empty, or not set at all';
}
// Evaluates as true because $var is set
if (isset($var)) {
echo '$var is set even though it is empty';
}
?>
It returns the float value of different variables:
<?php
$var = '122.34343The';
$float_value_of_var = floatval($var);
echo $float_value_of_var; // 122.34343
?>
It returns all defined variables, as an array:
<?php
$b = array(1, 1, 2, 3, 5, 8);
$arr = get_defined_vars();
// print $b
print_r($arr["b"]);
/* print path to the PHP interpreter (if used as a CGI)
* e.g. /usr/local/bin/php */
echo $arr["_"];
// print the command-line parameters if any
print_r($arr["argv"]);
// print all the server vars
print_r($arr["_SERVER"]);
// print all the available keys for the arrays of variables
print_r(array_keys(get_defined_vars()));
?>
It returns the resource type:
<?php
// prints: stream
$fp = fopen("foo", "w");
echo get_resource_type($fp) . "\n";
// prints: curl
$c = curl_init ();
echo get_resource_type($c) . "\n"; // works prior to PHP 8.0.0 as since 8.0 curl_init returns a CurlHandle object
?>
It returns the type of different variables:
<?php
$a = 3;
echo gettype($a) ;
?>
It returns the integer value of different variables:
<?php
echo intval(42);
?>
To check whether a variable is an array or not:
<?php
$a = "Hello";
echo "a is " . is_array($a) ;
?>
An array stores multiple values in one single variable.
<?php
$cms = array("Harry", "Lovish", "Rohan");
echo "Who needs chocolate? Is it" . $cms[0] . ", " .
$cms[1] . " or " . $cms[2] . "?";
?>
A function is a block of statements that can be used repeatedly in a program.
function NameOfTheFunction() {
//place PHP code here
}
It opens a non-persistent MySQL connection
mysqli_connect()
It returns the number of affected rows
mysqli_affected_rows()
It shows the Error description for the connection error
mysqli_connect_error()
It fetches all result rows as an array
mysqli_fetch_all()
It fetches a result row as an associative, a numeric array, or both
mysqli_fetch_array()
It fetches a result row as an associative array
mysqli_fetch_assoc()
It fetches one row from a result set and returns it as an enumerated array
mysqli_fetch_row()
It kills a MySQL thread
mysqli_kill()
It closes a database connection
mysqli_close()