ITC 240: Web Application ProgrammingSUBHASH PRAJAPATI

04/14/15

Review• Variable Types, Typecasting

• Constant

• Function Types

• Variable Scope

Today

• Functions: Passing by value, Passing by reference

• Conditionals

• Class Excercises

Passing by Value The default parameter will be passing by value. See following example:

<?php

function incrementTheVariable($var){$var++;return $var;

}

$a=5;

$b = incrementTheVariable($a);

echo $a;

echo $b;

?>

Passing by reference We can pass a variable by reference to a function so the function can modify the variable (both the variable point to the same content)

<?php

function incrementTheVariable(&$var){

$var++;

}

$a=5;

incrementTheVariable($a);

echo $a;

?>

Class Discussion

o What are the advantages of using functions?

o Should we echo inside a function? Why or why not?

Comparison OperationsOperator Meaning

$a == $b Equal

$a === $b Identical (both value and type are equal)

$a != $b Not Equal

$a !== $b Type and value are not equal

$a < $b Less than

$a <= $b Less than or equal to

$a > $b Great than

$a >= $b Greater than or equal to

Logical OperatorsOperator Meaning

OR, || OR

AND, && And

XOR Returns true if either is true. Returns false if both are true

! negation

Conditionals Executing different code on given different circumstances

Code branching/ Code separation

if statement

if statement if(TEST CONDITION) { //code that occurs if condition proves true}

Eg-

$salary = 50000;

echo "My salary is $" . $salary . "<br />";

if($s > 40000) {

echo "I'm Happy!";

}

// Now change the value 50000 to 15000 and see what happens

If/else statement

If/else statement

Eg-

$salary = 50000;

echo "My salary is $" . $salary . "<br />";

if($salary > 40000) {

echo "I'm Happy!";

}

else { echo “Life is not beautiful”;

}

Class Exercise 3.1• Write a program to determine the large number in between two numbers.

• Write a program to determine a number is odd or even.

If, elseif statement (chain)

elseif statement $salary = 50000;

echo "My salary is $" . $salary . "<br />";

If ($salary > 40000) {

echo "I'm Happy!";

}

else if ($salary > 30000) { echo “Life is still ok”;

}

else { echo “I don’t know what to say”;

}

Nested statements if ($x < $y) {

STATEMENTS_A }else { if ($x > $y) { STATEMENTS_B } else { STATEMENTS_C }}

Class Exercise 3.2

o Write a program to display the office is open or closed depending on time the user visits the website.

Office Hours: Mon-Fri 8:00 AM - 5:00 PM, Sat: 10:00 AM – 2:00 PM

Hint:

use php date() function to get the current hour/day

date (‘G’) gives 24-hour format of an hour without leading zeros.

date (‘l’) gives Monday through Saturday

Ternary Operator (condition) ? Value_if_true : Value_if_false

<?php

$opening_time = ( $day == “Sunday”) ? 12 : 9;

// above code is equivalent to :

if ($day == “Sunday”)

$opening_time = 12;

else

$opening_time = 9;

?>

switchselect one of many blocks of code to be executed.

switch (n) {

case label1:

code to be executed if n=label1;

break;

case label2:

code to be executed if n=label2;

break;

case label3:

code to be executed if n=label3;

break;

...

default:

code to be executed if n is different from all labels;

}

Class Exercise 3.3

o Write a program to greet the user with “Good Morning”, “Good Afternoon” or “Good Evening” depending on the time the user visits the website. Write this program utilizing switch statement.

Class Discussion

o What is different between =, ==, ===?

Some PHP String functions

o str_word_count ($string) – gives number of words in a string

o str_replace ($search $replace , $subject) – replace certain word in a string

o strlen ($string) – gives length of the string

o strtolower ($string) – converts to lower case

o strtoupper ($string) – converts to upper case

o trim ($string) – removes white space in both the ends of the string

Check PHP Manual for complete list of the functions

Class Exercise 3.4

o Write a program to check whether or not the given word is ‘seattle’ (regardless of the case of the string the user passes and has a space at the end/front). For eg – the function will return true in any of the following

‘seattle’, ‘Seattle’, ‘seattle ’, ‘ sEaTtle ’

Code Organization with PHP

o include and require

include “file_path”;

require “file_path”;

on failure:

require will produce a fatal error (E_COMPILE_ERROR) and stop the script

include will only produce a warning (E_WARNING) and the script will continue

o include_once and require_once

similar to include/require with the only difference being that if the code from a file has already been included, it will not be included again.

Code Organization with PHP<html>

<body>

<div class="menu">

<?php include 'menu.php';?>

</div>

<h1>Welcome to my home page!</h1>

<p>Some text.</p>

<p>Some more text.</p>

</body>

</html>

Class Exercise 3.5 Create a webpage template in the format as shown in the picture.

Create header, footer and nav templates to include in a webpage.