1. ITC 240: Web Application Programming SUBHASH PRAJAPATI 04/09/15

2. Review Client Server Architecture Server Side Language/ Client Side Language PHP Fundamentals/Syntax Variable Function

3. Today More on Variables & Functions Scope Functions: parameters & returns, passing by values Conditionals

4. Variables Container that can hold certain value (storing data into memory location) Starts with $ sign A noun Starts with underscore or letter Can be named with a-z, A-Z, _, 0-9 characters cAsE sEnSiTivE - $myVar and $Myvar are different

5. Functions A block of code to perform a task Starts with “function” keyword A verb Can be named with a-z, A-Z, _, 0-9 characters NOT case sensitive – myfunction() & myFunction() are same, but good practice is just use one.

6. Constants An identifier with an associated value which cannot be altered by the program during normal execution. Written in all UPPER_CASE <?php define ("SALES_TAX",.096); $itemPrice = 50; echo $totalPrice = $itemPrice + ($itemPrice * SALES_TAX); ?>

7. Variable Types Boolean $booleanVar = TRUE; // a boolean String $stringVar = "foo"; // a string $stringVar = 'foo'; // a string Integer $integerVar= 12; // an integer Float $floatVar= 12.5; // a floating point number Others: Array, Objects, Resource, Null (we’ll discuss later)

8. Function Types User-defined Functions The functions we define Build in Functions The functions that come with PHP for eg: date(); date ( string $format [, int $timestamp = time() ] ) // returns string

9. PHP date () function A program to display today’s date <?php echo date (‘Y’); // displays the current year echo date (‘m’); // displays the current month echo date (‘d’); // displays today’s date echo (‘H:i:s’); // Hour, minute, seconds // automatic copyright © 2013- ?> Check PHP date manual for complete list of the possible parametersdate manual

10. Class Exercise 2.1 Write the output of following: <?php echo date('l jS \of F Y h:i:s A'). " "; echo date(‘Y-m-d H:i:s’). " "; ?>

11. Class Exercise 2.2 mktime (hour,minute,second,month,day,year) // returns unix timestamp <?php $date =mktime(10, 21, 45, 4, 11, 2012); echo "Created date is ". date("Y-m-d h:i:sa", $date); ?>

12. Class Exercise 2.3 strtotime (string) // pass English phrase <?php $date=strtotime("tomorrow"); echo date("Y-m-d h:i:sa", $date). " "; $date=strtotime("next Monday"); echo date("Y-m-d h:i:sa", $date). " "; $date=strtotime("+6 Months"); echo date("Y-m-d h:i:sa", $date). " "; ?>

13. Class Exercise 2.3 strtotime (string) // pass English phrase <?php $date=strtotime("tomorrow"); echo date("Y-m-d h:i:sa", $date). " "; $date=strtotime("next Monday"); echo date("Y-m-d h:i:sa", $date). " "; $date=strtotime("+6 Months"); echo date("Y-m-d h:i:sa", $date). " "; ?>

14. Typecasting gettype ()/ settype() – built in functions <?php $foo = '1'; echo gettype($foo); // outputs 'string' settype($foo, 'integer'); echo gettype($foo); // outputs 'integer‘ // another way $a = (int) ‘55’; ?>

15. Typecasting OperatorChanges to (int)Integer (bool)Boolean (string)String (array)Array (object)Object (unset)NULL

16. User defined functions: Parameters Parameters: arguments passed to a function <?php function calculateSomething ($firstNumber, $secondNumber){ // do some calculations here } ?> In above example, $firstNumber and $secondNumber are two parameters

17. User defined functions: Return Value Return Value: the value returned by the function <?php function addNumber ($firstNumber, $secondNumber){ $sum = $firstNumber + $secondNumber; return $sum; } ?> In above example $sum is the return value

18. User defined functions: Function Call Function Call: Just defining the function does NOT do anything, until you call it. function doSomeMagic ($magicName) { // magic code here } // function call doSomeMagic (‘awesome magic’);

19. Class Exercise 2.4 Write a program (a function) to converts Fahrenheit to Celsius temperature. (for example 45.5 F = 7.5 C) Formula: C = ((F-32) * (5/9)) Celsius Scale: 0-100 Fahrenheit Scale: 32-212

20. Default parameter value <?php function orderDrink ($drink = “coffee") { // coffee is the default value return "Making a cup of $drink.\n"; } echo orderDrink (“Ice Tea"); echo orderDrink (); ?>

21. User defined Functions: return Function can also return without the value <?php function returnInMiddle () { // do something return; // code written here will not be executed } ?>

22. Variable Scope The variables inside user-defined function have local scope. Check output of following: <?php function addNumbers($a, $b){ $sum = $a + $b; return $sum; } echo $sum; $sum = addNumbers (5,6); echo $sum; ?>

23. Variable Scope The variables inside user-defined function have local scope. Check output of following <?php $myName = “Tina”; function printName(){ echo $myName; } printName (); ?>

24. Global Variable The variables inside user-defined function have local scope. Check output of following <?php $a = 1; $b = 2; function addNumbers () { global $a, $b; $sum = $a+$b; return $sum; } $sum = addNumbers (); echo $sum; ?>

25. Passing by reference We can pass a variable by reference to a function so the function can modify the variable <?php function incrementTheVariable(&$var){ $var++; } $a=5; incrementTheVariable($a); // $a is 6 here ?>