PHP tutorial : PHP 5 - Syntax, Variables Function in detail - part 3
continue to more info about array , file handling---------------------------------------------
PHP 5 Functions
The real power of PHP comes from its functions; it has more than 1000 built-in functions.
PHP User Defined Functions
Besides the built-in PHP functions, we can create our own functions.
A function is a block of statements that can be used repeatedly in a program.
A function will not execute immediately when a page loads.
A function will be executed by a call to the function.
Create a User Defined Function in PHP
A user defined function declaration starts with the word "function":
Syntax
function functionName() {
code to be executed;
}
Note: A function name can start with a letter or underscore (not a number).
Tip: Give the function a name that reflects what the function does!
Function names are NOT case-sensitive.
In the example below, we create a function named "writeMsg()". The opening curly brace ( { ) indicates the beginning of the function code and the closing curly brace ( } ) indicates the end of the function. The function outputs "Hello world!". To call the function, just write its name:
Example
<?php
function writeMsg() {
echo "Hello world!";
}
writeMsg(); // call the function
?>
PHP Function Arguments
Information can be passed to functions through arguments. An argument is just like a variable.
Arguments are specified after the function name, inside the parentheses. You can add as many arguments as you want, just separate them with a comma.
The following example has a function with one argument ($fname). When the familyName() function is called, we also pass along a name (e.g. Jani), and the name is used inside the function, which outputs several different first names, but an equal last name:
Example
<?php
function familyName($fname) {
echo "$fname Refsnes.<br>";
}
familyName("Jani");
familyName("Hege");
familyName("Stale");
familyName("Kai Jim");
familyName("Borge");
?>
The following example has a function with two arguments ($fname and $year):
Example
<?php
function familyName($fname, $year) {
echo "$fname Refsnes. Born in $year <br>";
}
familyName("Hege", "1975");
familyName("Stale", "1978");
familyName("Kai Jim", "1983");
?>
PHP Default Argument Value
The following example shows how to use a default parameter. If we call the function setHeight() without arguments it takes the default value as argument:
Example
<?php
function setHeight($minheight = 50) {
echo "The height is : $minheight <br>";
}
setHeight(350);
setHeight(); // will use the default value of 50
setHeight(135);
setHeight(80);
?>
PHP Functions - Returning values
To let a function return a value, use the return statement:
Example
<?php
function sum($x, $y) {
$z = $x + $y;
return $z;
}
echo "5 + 10 = " . sum(5, 10) . "<br>";
echo "7 + 13 = " . sum(7, 13) . "<br>";
echo "2 + 4 = " . sum(2, 4);
?>
___________________________________________________
demo_function2
<!DOCTYPE html>
<html>
<body>
<?php
function familyName($fname) {
echo "$fname Refsnes.<br>";
}
familyName("Jani");
familyName("Hege");
familyName("Stale");
familyName("Kai Jim");
familyName("Borge");
?>
</body>
</html>
***********
Jani Refsnes.
Hege Refsnes.
Stale Refsnes.
Kai Jim Refsnes.
Borge Refsnes.
___________________________________________________
demo_function3
<!DOCTYPE html>
<html>
<body>
<?php
function familyName($fname, $year) {
echo "$fname Refsnes. Born in $year <br>";
}
familyName("Hege","1975");
familyName("Stale","1978");
familyName("Kai Jim","1983");
?>
</body>
</html>
***********
Hege Refsnes. Born in 1975
Stale Refsnes. Born in 1978
Kai Jim Refsnes. Born in 1983
___________________________________________________
demo_function4
<!DOCTYPE html>
<html>
<body>
<?php
function setHeight($minheight = 50) {
echo "The height is : $minheight <br>";
}
setHeight(350);
setHeight();
setHeight(135);
setHeight(80);
?>
</body>
</html>
***********
The height is : 350
The height is : 50
The height is : 135
The height is : 80
___________________________________________________
demo_function5
<!DOCTYPE html>
<html>
<body>
<?php
function sum($x, $y) {
$z = $x + $y;
return $z;
}
echo "5 + 10 = " . sum(5,10) . "<br>";
echo "7 + 13 = " . sum(7,13) . "<br>";
echo "2 + 4 = " . sum(2,4);
?>
</body>
</html>
***********
5 + 10 = 15
7 + 13 = 20
2 + 4 = 6
___________________________________________________
PHP 5 Arrays
An array stores multiple values in one single variable:
Example
<?php
$cars = array("Volvo", "BMW", "Toyota");
echo "I like " . $cars[0] . ", " . $cars[1] . " and " . $cars[2] . ".";
?>
What is an Array?
An array is a special variable, which can hold more than one value at a time.
If you have a list of items (a list of car names, for example), storing the cars in single variables could look like this:
$cars1 = "Volvo";
$cars2 = "BMW";
$cars3 = "Toyota";
However, what if you want to loop through the cars and find a specific one? And what if you had not 3 cars, but 300?
The solution is to create an array!
An array can hold many values under a single name, and you can access the values by referring to an index number.
Create an Array in PHP
In PHP, the array() function is used to create an array:
array();
In PHP, there are three types of arrays:
Indexed arrays - Arrays with a numeric index
Associative arrays - Arrays with named keys
Multidimensional arrays - Arrays containing one or more arrays
PHP Indexed Arrays
There are two ways to create indexed arrays:
The index can be assigned automatically (index always starts at 0), like this:
$cars = array("Volvo", "BMW", "Toyota");
or the index can be assigned manually:
$cars[0] = "Volvo";
$cars[1] = "BMW";
$cars[2] = "Toyota";
The following example creates an indexed array named $cars, assigns three elements to it, and then prints a text containing the array values:
Example
<?php
$cars = array("Volvo", "BMW", "Toyota");
echo "I like " . $cars[0] . ", " . $cars[1] . " and " . $cars[2] . ".";
?>
Get The Length of an Array - The count() Function
The count() function is used to return the length (the number of elements) of an array:
Example
<?php
$cars = array("Volvo", "BMW", "Toyota");
echo count($cars);
?>
Loop Through an Indexed Array
To loop through and print all the values of an indexed array, you could use a for loop, like this:
Example
<?php
$cars = array("Volvo", "BMW", "Toyota");
$arrlength = count($cars);
for($x = 0; $x < $arrlength; $x++) {
echo $cars[$x];
echo "<br>";
}
?>
PHP Associative Arrays
Associative arrays are arrays that use named keys that you assign to them.
There are two ways to create an associative array:
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
or:
$age['Peter'] = "35";
$age['Ben'] = "37";
$age['Joe'] = "43";
The named keys can then be used in a script:
Example
<?php
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
echo "Peter is " . $age['Peter'] . " years old.";
?>
Loop Through an Associative Array
To loop through and print all the values of an associative array, you could use a foreach loop, like this:
Example
<?php
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
foreach($age as $x => $x_value) {
echo "Key=" . $x . ", Value=" . $x_value;
echo "<br>";
}
?>
Multidimensional Arrays
Multidimensional arrays will be explained in the PHP advanced section.
Complete PHP Array Reference
For a complete reference of all array functions, go to our complete PHP Array Reference.
The reference contains a brief description, and examples of use, for each function!
___________________________________________________
demo_array_num
<!DOCTYPE html>
<html>
<body>
<?php
$cars = array("Volvo", "BMW", "Toyota");
echo "I like " . $cars[0] . ", " . $cars[1] . " and " . $cars[2] . ".";
?>
</body>
</html>
*********** I like Volvo, BMW and Toyota.
___________________________________________________
demo_array_num
<!DOCTYPE html>
<html>
<body>
<?php
$cars = array("Volvo", "BMW", "Toyota");
echo "I like " . $cars[0] . ", " . $cars[1] . " and " . $cars[2] . ".";
?>
</body>
</html>
*********** I like Volvo, BMW and Toyota.
___________________________________________________
demo_array_length
<!DOCTYPE html>
<html>
<body>
<?php
$cars = array("Volvo", "BMW", "Toyota");
echo count($cars);
?>
</body>
</html>
*********** 3
___________________________________________________
demo_array_num_loop
<!DOCTYPE html>
<html>
<body>
<?php
$cars = array("Volvo", "BMW", "Toyota");
$arrlength = count($cars);
for($x = 0; $x < $arrlength; $x++) {
echo $cars[$x];
echo "<br>";
}
?>
</body>
</html>
***********
Volvo
BMW
Toyota
___________________________________________________
demo_array_assoc
<!DOCTYPE html>
<html>
<body>
<?php
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
echo "Peter is " . $age['Peter'] . " years old.";
?>
</body>
</html>
*********** Peter is 35 years old.
___________________________________________________
demo_array_assoc_loop
<!DOCTYPE html>
<html>
<body>
<?php
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
foreach($age as $x => $x_value) {
echo "Key=" . $x . ", Value=" . $x_value;
echo "<br>";
}
?>
</body>
</html>
***********
Key=Peter, Value=35
Key=Ben, Value=37
Key=Joe, Value=43
___________________________________________________
PHP 5 Sorting Arrays
The elements in an array can be sorted in alphabetical or numerical order, descending or ascending.
PHP - Sort Functions For Arrays
In this chapter, we will go through the following PHP array sort functions:
sort() - sort arrays in ascending order
rsort() - sort arrays in descending order
asort() - sort associative arrays in ascending order, according to the value
ksort() - sort associative arrays in ascending order, according to the key
arsort() - sort associative arrays in descending order, according to the value
krsort() - sort associative arrays in descending order, according to the key
Sort Array in Ascending Order - sort()
The following example sorts the elements of the $cars array in ascending alphabetical order:
Example
<?php
$cars = array("Volvo", "BMW", "Toyota");
sort($cars);
?>
The following example sorts the elements of the $numbers array in ascending numerical order:
Example
<?php
$numbers = array(4, 6, 2, 22, 11);
sort($numbers);
?>
Sort Array in Descending Order - rsort()
The following example sorts the elements of the $cars array in descending alphabetical order:
Example
<?php
$cars = array("Volvo", "BMW", "Toyota");
rsort($cars);
?>
The following example sorts the elements of the $numbers array in descending numerical order:
Example
<?php
$numbers = array(4, 6, 2, 22, 11);
rsort($numbers);
?>
Sort Array (Ascending Order), According to Value - asort()
The following example sorts an associative array in ascending order, according to the value:
Example
<?php
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
asort($age);
?>
Sort Array (Ascending Order), According to Key - ksort()
The following example sorts an associative array in ascending order, according to the key:
Example
<?php
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
ksort($age);
?>
Sort Array (Descending Order), According to Value - arsort()
The following example sorts an associative array in descending order, according to the value:
Example
<?php
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
arsort($age);
?>
Sort Array (Descending Order), According to Key - krsort()
The following example sorts an associative array in descending order, according to the key:
Example
<?php
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
krsort($age);
?>
Complete PHP Array Reference
For a complete reference of all array functions, go to our complete PHP Array Reference.
The reference contains a brief description, and examples of use, for each function!
___________________________________________________
demo_array_sort_alpha
<!DOCTYPE html>
<html>
<body>
<?php
$cars = array("Volvo", "BMW", "Toyota");
sort($cars);
$clength = count($cars);
for($x = 0; $x < $clength; $x++) {
echo $cars[$x];
echo "<br>";
}
?>
</body>
</html>
***********
BMW
Toyota
Volvo
___________________________________________________
demo_array_sort_num
<!DOCTYPE html>
<html>
<body>
<?php
$numbers = array(4, 6, 2, 22, 11);
sort($numbers);
$arrlength = count($numbers);
for($x = 0; $x < $arrlength; $x++) {
echo $numbers[$x];
echo "<br>";
}
?>
</body>
</html>
***********
2
4
6
11
22
___________________________________________________
demo_array_rsort_alpha
<!DOCTYPE html>
<html>
<body>
<?php
$cars = array("Volvo", "BMW", "Toyota");
rsort($cars);
$clength = count($cars);
for($x = 0; $x < $clength; $x++) {
echo $cars[$x];
echo "<br>";
}
?>
</body>
</html>
***********
Volvo
Toyota
BMW
___________________________________________________
demo_array_rsort_num
<!DOCTYPE html>
<html>
<body>
<?php
$numbers = array(4, 6, 2, 22, 11);
rsort($numbers);
$arrlength = count($numbers);
for($x = 0; $x < $arrlength; $x++) {
echo $numbers[$x];
echo "<br>";
}
?>
</body>
</html>
***********
22
11
6
4
2
___________________________________________________
demo_array_asort
<!DOCTYPE html>
<html>
<body>
<?php
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
asort($age);
foreach($age as $x => $x_value) {
echo "Key=" . $x . ", Value=" . $x_value;
echo "<br>";
}
?>
</body>
</html>
***********
Key=Peter, Value=35
Key=Ben, Value=37
Key=Joe, Value=43
___________________________________________________
demo_array_ksort
<!DOCTYPE html>
<html>
<body>
<?php
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
ksort($age);
foreach($age as $x => $x_value) {
echo "Key=" . $x . ", Value=" . $x_value;
echo "<br>";
}
?>
</body>
</html>
***********
Key=Ben, Value=37
Key=Joe, Value=43
Key=Peter, Value=35
___________________________________________________
demo_array_arsort
<!DOCTYPE html>
<html>
<body>
<?php
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
arsort($age);
foreach($age as $x => $x_value) {
echo "Key=" . $x . ", Value=" . $x_value;
echo "<br>";
}
?>
</body>
</html>
***********
Key=Joe, Value=43
Key=Ben, Value=37
Key=Peter, Value=35
___________________________________________________
demo_array_krsort
<!DOCTYPE html>
<html>
<body>
<?php
$age = array("Peter"=>"35", "Ben"=>"37", "Joe"=>"43");
krsort($age);
foreach($age as $x => $x_value) {
echo "Key=" . $x . ", Value=" . $x_value;
echo "<br>";
}
?>
</body>
</html>
***********
Key=Peter, Value=35
Key=Joe, Value=43
Key=Ben, Value=37
___________________________________________________
PHP 5 Global Variables - Superglobals
Superglobals were introduced in PHP 4.1.0, and are built-in variables that are always available in all scopes.
PHP Global Variables - Superglobals
Several predefined variables in PHP are "superglobals", which means that they are always accessible, regardless of scope - and you can access them from any function, class or file without having to do anything special.
The PHP superglobal variables are:
$GLOBALS
$_SERVER
$_REQUEST
$_POST
$_GET
$_FILES
$_ENV
$_COOKIE
$_SESSION
This chapter will explain some of the superglobals, and the rest will be explained in later chapters.
PHP $GLOBALS
$GLOBALS is a PHP super global variable which is used to access global variables from anywhere in the PHP script (also from within functions or methods).
PHP stores all global variables in an array called $GLOBALS[index]. The index holds the name of the variable.
The example below shows how to use the super global variable $GLOBALS:
Example
<?php
$x = 75;
$y = 25;
function addition() {
$GLOBALS['z'] = $GLOBALS['x'] + $GLOBALS['y'];
}
addition();
echo $z;
?>
In the example above, since z is a variable present within the $GLOBALS array, it is also accessible from outside the function!
PHP $_SERVER
$_SERVER is a PHP super global variable which holds information about headers, paths, and script locations.
The example below shows how to use some of the elements in $_SERVER:
Example
<?php
echo $_SERVER['PHP_SELF'];
echo "<br>";
echo $_SERVER['SERVER_NAME'];
echo "<br>";
echo $_SERVER['HTTP_HOST'];
echo "<br>";
echo $_SERVER['HTTP_REFERER'];
echo "<br>";
echo $_SERVER['HTTP_USER_AGENT'];
echo "<br>";
echo $_SERVER['SCRIPT_NAME'];
?>
The following table lists the most important elements that can go inside $_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 someone@w3schools.com)
$_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
PHP $_REQUEST
PHP $_REQUEST is used to collect data after submitting an HTML form.
The example below shows a form with an input field and a submit button. When a user submits the data by clicking on "Submit", the form data is sent to the file specified in the action attribute of the <form> tag. In this example, we point to this file itself for processing form data. If you wish to use another PHP file to process form data, replace that with the filename of your choice. Then, we can use the super global variable $_REQUEST to collect the value of the input field:
Example
<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") {
// collect value of input field
$name = $_REQUEST['fname'];
if (empty($name)) {
echo "Name is empty";
} else {
echo $name;
}
}
?>
</body>
</html>
PHP $_POST
PHP $_POST is widely used to collect form data after submitting an HTML form with method="post". $_POST is also widely used to pass variables.
The example below shows a form with an input field and a submit button. When a user submits the data by clicking on "Submit", the form data is sent to the file specified in the action attribute of the <form> tag. In this example, we point to the file itself for processing form data. If you wish to use another PHP file to process form data, replace that with the filename of your choice. Then, we can use the super global variable $_POST to collect the value of the input field:
Example
<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") {
// collect value of input field
$name = $_POST['fname'];
if (empty($name)) {
echo "Name is empty";
} else {
echo $name;
}
}
?>
</body>
</html>
PHP $_GET
PHP $_GET can also be used to collect form data after submitting an HTML form with method="get".
$_GET can also collect data sent in the URL.
Assume we have an HTML page that contains a hyperlink with parameters:
<html>
<body>
<a href="test_get.php?subject=PHP&web=W3schools.com">Test $GET</a>
</body>
</html>
When a user clicks on the link "Test $GET", the parameters "subject" and "web" are sent to "test_get.php", and you can then access their values in "test_get.php" with $_GET.
The example below shows the code in "test_get.php":
Example
<html>
<body>
<?php
echo "Study " . $_GET['subject'] . " at " . $_GET['web'];
?>
</body>
</html>
Tip: You will learn more about $_POST and $_GET in the PHP Forms chapter.
___________________________________________________
demo_global_global
<!DOCTYPE html>
<html>
<body>
<?php
$x = 75;
$y = 25;
function addition() {
$GLOBALS['z'] = $GLOBALS['x'] + $GLOBALS['y'];
}
addition();
echo $z;
?>
</body>
</html>
*********** 100
___________________________________________________
demo_global_server
<!DOCTYPE html>
<html>
<body>
<?php
echo $_SERVER['PHP_SELF'];
echo "<br>";
echo $_SERVER['SERVER_NAME'];
echo "<br>";
echo $_SERVER['HTTP_HOST'];
echo "<br>";
echo $_SERVER['HTTP_REFERER'];
echo "<br>";
echo $_SERVER['HTTP_USER_AGENT'];
echo "<br>";
echo $_SERVER['SCRIPT_NAME'];
?>
</body>
</html>
***********
/php/demo_global_server.php
www.w3schools.com
www.w3schools.com
demo_global_server
Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:49.0) Gecko/20100101 Firefox/49.0
/php/demo_global_server.php
___________________________________________________
demo_global_request
<!DOCTYPE html>
<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") {
// collect value of input field
$name = $_REQUEST['fname'];
if (empty($name)) {
echo "Name is empty";
} else {
echo $name;
}
}
?>
</body>
</html>
********* form with button
Name: [ box ] [submit query] button
___________________________________________________
demo_global_post
<!DOCTYPE html>
<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") {
// collect value of input field
$name = $_POST['fname'];
if (empty($name)) {
echo "Name is empty";
} else {
echo $name;
}
}
?>
</body>
</html>
********* form with button
Name: [ box ] [submit query] button
___________________________________________________
demo_global_get
<!DOCTYPE html>
<html>
<body>
<a href="test_get.php?subject=PHP&web=W3schools.com">Test $GET</a>
</body>
</html>
******** url link
Test $GET [link to]
___________________________________________________
read more
http://adf.ly/1hAWyp
http://adf.ly/1hAX15
http://adf.ly/1hAX4k
http://adf.ly/1hAX7f
No comments:
Post a Comment
Note: only a member of this blog may post a comment.