Php my sql - functions - arrays - tutorial - programmerblog.net

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Introduction to Functions and Arrays
By ProgrammerBlog.net http://programmerblog.net/

PHP Fundamentals: Functions
 A set of constructs which allow the programmer to break up their code
into smaller, more manageable, chunks which can be called by name
and which may or may not return a value.
 function function_name (parameters) {
function-body
}
 function helloWorld(){
echo "HelloWorld"; //No out put is shown
}

Functions: Passing Parameters
 Passing parameters by value
– function salestax($price,$tax) {
$total = $price + ($price * $tax
echo "Total cost: $total";
}
salestax(15.00,.075);
$pricetag = 15.00;
$salestax = .075;
salestax($pricetag, $salestax);

Functions: Passing Parameters
 Passing parameters by reference
$cost = 20.00;
$tax = 0.05;
function calculate_cost(&$cost, $tax)
{
// Modify the $cost variable
$cost = $cost + ($cost * $tax);
// Perform some random change to the $tax variable.
$tax += 4;
}
calculate_cost($cost,$tax);
echo "Tax is: ". $tax*100."<br />";
echo "Cost is: $". $cost."<br />";

Functions: Default Argument
Values
 Default values are automatically assigned to the argument if no other value is
provided
function salestax($price,$tax=.0575) {
$total = $price + ($price * $tax);
}
$price = 15.47;
salestax($price);

Functions: Optional Arguments
 Certain arguments can be designated as optional by placing them at the end of
the list and assigning them a default value of nothing .
function salestax($price, $tax="") {
}
salestax(42.00);
function calculate($price,$price2="",$price3="") {
echo $price + $price2 + $price3;
}
calculate(10,"", 3);

Functions: Returning Values from
a Function
 You can pass data back to the caller by way of the return keyword.
 function salestax($price,$tax=.0575) {
return $total;
}
$total = salestax(6.50);
 Returning Multiple Values
function retrieve_user_profile() {
$user[] = "Jason";
$user[] = "jason@example.com";
return $user;
}
list($name,$email) = retrieve_user_profile();
echo "Name: $name, email: $email ";

Functions: Nesting Functions
 defining and invoking functions within functions
function salestax($price,$tax)
function convert_pound($dollars, $conversion=1.6) {
return $dollars * $conversion;
}
echo "Total cost in dollars: $total. Cost in British pounds: "
. convert_pound($total);
}
salestax(15.00,.075);
echo convert_pound(15);

Functions: Recursive Functions
functions that call themselves
function nfact($n) {
if ($n == 0) {
return 1;
}else {
return $n * nfact($n - 1);
}
}
//call to function
nfact($num) ;

Functions: Variable Functions
 Functions with parameters on run time
function hello(){
if (func_num_args()>0){
$arg=func_get_arg(0); //Thefirstargumentisatposition0
echo "Hello$arg";
} else {
echo "HelloWorld";
}
}
hello("Reader"); //Displays"HelloReader"
hello(); //Displays"HelloWorld"

Server Side Includes (SSI):
include() function
 Include function
 You can insert the content of one PHP file into another PHP file before the server
executes it, with the include() or require() function. (e.g. Header, Menu, footer)
 The include() function takes all the content in a specified file and includes it in the
current file
 include() generates a warning, but the script will continue execution
<html>
<body>
<?php include("header.php"); ?>
<h1>Welcome to my home page!</h1>
<p>Some text.</p>
</body>
</html>

include() function
 <html>
<body>
<div class="leftmenu">
<?php include("menu.php"); ?>
</div>
<h1>Welcome to my home page.</h1>
<p>Some text.</p>
</body>
</html>

include() function
<html>
<body>
<div class="leftmenu">
<a href="/default.php">Home</a>
<a href="/tutorials.php">Tutorials</a>
<a href="/references.php">References</a>
<a href="/examples.php">Examples</a>
<a href="/about.php">About Us</a>
<a href="/contact.php">Contact Us</a>
</div>
<h1>Welcome to my home page!</h1>
<p>Some text.</p>
</body>
</html>

require() function
 Require function
require() generates a fatal error, and the script will stop
include() generates a warning, but the script will continue execution
<html>
<body>
<?php
require("wrongFile.php");
echo "Hello World!";
?>
</body>
</html>
 It is recommended to use the require() function instead of include(), because
scripts should not continue after an error.

PHP Built In Functions
 Math functions
 http://www.w3schools.com/php/php_ref_math.asp
– pi() Returns the value of PI
– pow() Returns the value of x to the power of y
– rad2deg() Converts a radian number to a degree
– rand() Returns a random integer
– round() Rounds a number to the nearest integer
– sin() Returns the sine of a number
– sinh() Returns the hyperbolic sine of a number
– sqrt() Returns the square root of a number
– srand() Seeds the random number generator
– tan() Returns the tangent of an angle
– tanh()
– abs() Returns the absolute value of a number

PHP Built In Misc. Functions
 Constants
– M_LN10 Returns the natural logarithm of 10 (approx. 2.302)
– M_PI Returns PI (approx. 3.14159)
– M_SQRT2 Returns the square root of 2 (approx. 1.414)
 Miscellaneous Functions
– Strlen Returns length of a string
– count() Returns the count of an array.
– Strtolower strtolower() to lower case.
– strtoupper() strtoupper() convert string to upper case

PHP Fundaments - Arrays
 Arrays are ordered collections of items, called elements
 Each element has a value, and is identified by a key that is unique to the array It
belongs to
 In PHP, there are three kind of arrays:
– Numeric array - An array with a numeric index
– Associative array - An array where each ID key is associated with a value
– Multidimensional array - An array containing one or more arrays.
– $a = array();
– $state[0] = "Delaware";
– $a = array (10, 20, 30);
– $a = array (’a’ => 10, ’b’ => 20, ’cee’ => 30);
– $a = array (5 => 1, 3 => 2, 1 => 3,);

 Numeric Arrays:
– A numeric array stores each array element with a numeric index.
– $cars = array("Saab","Volvo","BMW","Toyota");
– $cars[0]="Saab"; //2nd
way of declaring arrays
– $cars[1]="Volvo";
– $cars[2]="BMW";
– $cars[3]="Toyota";
– echo $cars[0] . " and " . $cars[1] . " are Swedish cars.";
 Associative Arrays
– An associative array, each ID key is associated with a value.
– $ages = array(«John"=>32, «Jane"=>30, «David"=>34);
– $ages[‘John '] = "32";
– $ages[‘Jane '] = "30";
– $ages[‘David '] = "34";
– $states = array (0 => "Alabama", "1" => "Alaska"..."49" => "Wyoming"); //numeric
– $states = array ("OH" => "Ohio", "PA" => "Pennsylvania", "NY" => "New York")

 Multidimensional Arrays
 Arrays of arrays, known as multidimensional arrays
 In a multidimensional array, each element in the main array can also be an array.
 $cars = array ( “Toyota"=>array ( “Corolla“, " Camry“, "Toyota 4Runner” ),
“Suzuki"=>array ( “Vitara” ),
“Honda"=>array ( "Accord“, “Sedan“, “Odyssey” ) );
 echo "Is " . $ cars [Toyota '][2] . " a member of the Toyota cars?“;
 Is Toyota 4Runner a member of the Toyota cars?
 $states = array (
"Ohio" => array ("population" => "11,353,140", "capital" => "Columbus"),
"Nebraska" => array ("population" => "1,711,263", "capital" => "Omaha")
)

PHP Fundaments – Printing Arrays
 print_r() and var_dump()
 var_dump
– var_dump() outputs the data types of each value
– var_dump() is capable of outputting the value of more than one variable
– var_dump($states);
– $a = array (1, 2, 3);
– $b = array (’a’ => 1, ’b’ => 2, ’c’ => 3);
– var_dump ($a + $b); // creates union of arrays
– If 2 arrays have common elements and also share same string or numeric key will
appearance in result or output
 print_r
– print_r can return its output as a string, as opposed to writing it to the script’s standard
output
– print_r($states);

PHP Fundaments – Comparing -
Counting Arrays
 $a = array (1, 2, 3);
$b = array (1 => 2, 2 => 3, 0 => 1);
$c = array (’a’ => 1, ’b’ => 2, ’c’ => 3);
var_dump ($a == $b); // True
var_dump ($a === $b); // False returns true only if the array contains the
same key/value pairs in the same order
var_dump ($a == $c); // True
var_dump ($a === $c); // False
 $a = array (1, 2, 4);
 $b = array();
 $c = 10;
 echo count ($a); // Outputs 3
 echo count ($b); // Outputs 0
 echo count ($c); // Outputs 1
 is_array() function : echo in_array ($a, 2); // True

PHP Fundaments – Flipping and
Reversing , Range
 array_flip()
– Exchanges all keys with their associated values in an array
$trans = array("a" => 1, "b" => 1, "c" => 2);
$trans = array_flip($trans);
print_r($trans);
– Output = Array ( [1] => b [2] => c )
 array_reverse()
– Return an array with elements in reverse order
 array_values()
– array_values — Return all the values of an array
– $array = array("size" => "XL", "color" => "gold");
print_r(array_values($array));
– array_keys — Return all the keys of an array
 range()
– The range() function provides an easy way to quickly create and fill an array consisting
of a range of low and high integer values.
– $die = range(0,6); // Same as specifying $die = array(0,1,2,3,4,5,6)
By ProgrammerBlog.net http://programmerblog.net/By ProgrammerBlog.net http://programmerblog.net/

PHP Fundaments – Sorting Arrays
 There are many functions in PHP core that provide various methods of sorting
array contents.
 sort
– $array = array(’a’ => ’foo’, ’b’ => ’bar’, ’c’ => ’baz’);
sort($array);
var_dump($array);
 asort //to maintain key association,
- $array = array(’a’ => ’foo’, ’b’ => ’bar’, ’c’ => ’baz’);
asort($array);
var_dump($array);
 rsort,
 arsort // sorting an array in descending order

PHP Fundaments – Arrays as Stack
and Queues
 Stack Last in First Out.
 array_push()
– $stack = array();
array_push($stack, ’bar’, ’baz’);
var_dump($stack);
 array_pop()
– $states = array("Ohio","New York","California","Texas");
– $state = array_pop($states); // $state = "Texas"
 Queues
 array_shift, Shift an element off the beginning of array
 array_unshift - Prepend one or more elements to the beginning of an array
$stack = array(’qux’, ’bar’, ’baz’);
$first_element = array_shift($stack);
var_dump($stack);
array_unshift($stack, ’foo’);
var_dump($stack);

Super Globals
 Several predefined variables in PHP are "superglobals", which means
they are available in all scopes throughout a script. There is no need to
do global $variable; to access them within functions or methods.
 $GLOBALS
 $_SERVER
 $_GET
 $_POST
 $_FILES
 $_COOKIE
 $_SESSION
 $_REQUEST
 $_ENV

Features – Super Globals
 $GLOBALS — References all variables available in global scope
 <?php
function test() {
$foo = "local variable";
echo '$foo in global scope: ' . $GLOBALS["foo"] . "n";
echo '$foo in current scope: ' . $foo . "n";
}
$foo = "Example content";
test();
?>
 $_SERVER -- $HTTP_SERVER_VARS [deprecated] — Server and execution environment
information
 <?php
echo $_SERVER['SERVER_NAME'];
?>

Super Globals
 $_ENV -- $HTTP_ENV_VARS [deprecated] — Environment variables
 <?php
echo 'My username is ' .$_ENV["USER"] . '!';
?>
 $ip = $_SERVER['REMOTE_ADDR'];

Super Globals
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