Tutorial 2
BEGINNING PHP CODING
1. All PHP files have an extension of .php
2. All PHP will start with the following code
<?php
code
?>
3. In order to comment a code, it begins with two forward slashes // or a # sign. PHP engine usually ignores these lines. Comments can be used to annotate codes to make them more readable
# This starts the comments
// This also starts the comments
Multi lines comment is also possible. It stars /* and ends with */.
/*
This is the start of the comment.
Anything within this lines will not
Be interpreted by the PHP engine
*/
4. Every line in PHP needs a terminator. The terminator is a semicolon ;
<?php
echo "This is my first PHP program " ;
?>
Variables
1. In PHP variables starts with $ sign followed by the name.
$variable1
<?php
// Adding two numbers together
// Assigning the variable with the value 88
$num1 = 88;
$num2 = 100;
echo "The first number is", $num1;
echo " The second number is ", $num2 ;
// Adding the two numbers
echo " The total is ", $num1 + $num2;
?>
For the list of logical and mathematical operators, please refer to the prescribed text.
Data Types
The six standard data types in PHP are
Integer - Whole number, 10
Double - Floating point number , 9.999
String - AlphaNumeric characters, " This is PHP "
Boolean - True/False values, TRUE
Object - Instance of class
Array - An ordered set of keys and values
Testing the variable types
<html>
<head>
<title>Listing 4.1 Testing the type of a variable</title>
</head>
<body>
<?php
$testing; // declare without assigning
print gettype($testing); // null
print "<br>";
$testing = 5;
print gettype($testing); // integer
print "<br>";
$testing = "five";
print gettype($testing); // string
print("<br>");
$testing = 5.0;
print gettype($testing); // double
print("<br>");
$testing = true;
print gettype($testing); // boolean
print "<br>";
?>
</body>
</html>
FLOW CONTROL
1. If Statements
<?php
$subject = "ITC382" ;
If ($subject == "ITC382") {
Echo " I am in ITC382 class";
}
?>
2. If .. else statements
<?php
$subject = "ITC254" ;
If ($subject == "ITC382") {
Echo " I am in ITC382 class";}
Else {echo " I am in the wrong class";) }
?>
3. If..elseif ..else statements
<?php
$subject = "ITC254" ;
If ($subject == "ITC382") {
Echo " I am in ITC382 class";}
Else if ($subject == "ITC254") {
echo "I am in ITC254 class ";}
else { echo " I'm not too sure which class I should be in. Maybe I should be in $subject"; }
?>
4. Switch statements
Switch is commonly used to execute different codes based on each expression used.
<?php
$subject = "ITC382";
switch ($subject) {
case "ITC254":
echo "I am in ITC254 class";
break;
case "ITC382":
echo "I am in ITC382 class";
break;
default:
print "I must have gotten lost again, I am suppose to be in $subject";
break;
}
?>
5. While statements
A continuos loop until a condition is reached.
<?php
$count = 1;
while ($count < 10) {
echo " This is line $count", "<br>";
$count++; // Increment count by 1
}
?>
6. Do..While statements
It is similar to the Do statement except that termination is at the end of the code.
<?php
$count = 0;
do {
echo " This is line $count", "<br>";
$count++; // Increment count by 1
} while ($count < 10);
?>
7. For statements
For statements are also similar to while statements, it is a more structured way to write looping statements with the initialization, testing and modification expression nested within the command.
<?php
for ($count =1; $count <10; $count++) {
echo "This is line $count", "<br>";
}
?>
FUNCTIONS
Functions are blocks of code that you can call from the main program.
<?php
function print2lines() {
echo "This is line 1", "<br>";
echo "This is line 2", "<br>";
}
print2lines();
You can also pass arguments into a function
<?php
function printlines($txt) {
echo " $txt <br>";
}
printlines("This is line 1");
printlines("This is line 2");
printlines("This is line 3");
?>
You can also get the function to return an argument
<?php
function addnums ($num1, $num2) {
$result = $num1 + $num2;
return $result;
}
echo addnums(5,9);
// print 14
?>
Variables declared in a function remains only in the function. You can however use global variables should you wish to use variables within a function.
<?php
$value = 100;
function currentmoney() {
global $value;
echo " I currently have RM $value <br>";
}
currentmoney();
?>
ARRAYS
Creating arrays
In order to create an array, you would need to you the array function:
$lecturers = array("Yann", "Sam", "Ven Yu", "Tony", "Anitha");
You can also do this as well
$lecturers[] = "Yann" ;
$lecturers[] = "Sam";
$lecturers[] = "Ven Yu";
$lecturers[] = "Tony";
$lecturers[] = "Anitha";
Both will create an array called lecturers with 5 elements. By default the first element starts at position 0.
<?php
$lecturers = array("Yann", "Sam", "Ven Yu", "Tony", "Anitha");
echo $lecturers(1) ; // This will print Sams name
?>
Associative Arrays
Instead of using numbers, you can also use named keys to number the arrays instead as illustrated in the following example.
$lecturers = array (
"name" => "Yann",
"dept" => "VIGIM",
"subjects" => "ITC382"
);
If you write
Echo $lecturers['dept']; // this will return VIGIM
You can also make additions to an already existing associative array.
$lecturers['interests'] = "Video Games";
Multidimensional Arrays
This holds arrays of an array.
<?php
$lecturers = array (
array (
"name" => "Yann",
"dept" => "VIGIM",
"subjects" => "ITC382"
),
array (
"name" => "Sam",
"dept" => "VIGIM",
"subjects" => "ITC211"
),
array (
"name" => "Tony",
"dept" => "MT",
"subjects" => "ITC123"
),
);
echo $character[1]['subjects']; // this will print out ITC211
?>
OBJECTS
An object is typically a sort of container that consists of
variables
functions
etc
It is similar to a class ohject in JAVA
<?php
class lecturers {
var $name = "Yann";
var $subjectcode = "ITC382" ;
var $subjectname = "Client Server Applications";
}
$mylecturer = new lecturers();
echo "My name is ".$mylecturer -> name. " and I teach " .$mylecturer -> subjectcode." " .$mylecturer -> subjectname;
?>
You can also change the properties of an object in the code as illustrated.
<?php
class lecturers {
var $name = "Yann";
var $subjectcode = "ITC382" ;
var $subjectname = "Client Server Applications";
}
$mylecturer = new lecturers();
echo "My name is ".$mylecturer -> name. " and I teach " .$mylecturer -> subjectcode." " .$mylecturer -> subjectname;
// changing the object properties
echo "<br> This is to relfect the changes in object properties <br>";
$mylecturer -> name = "Sam";
$mylecturer -> subjectcode = "ITC211";
$mylecturer -> subjectname = "Multimedia Systems";
echo "My name is ".$mylecturer -> name. " and I teach " .$mylecturer -> subjectcode." " .$mylecturer -> subjectname;
?>
You can also add methods into your class objects as illustrated.
<?php
class displayname {
function name() {
echo "My name is Yann " ;
}
}
$name = new displayname();
$name -> name();
?>
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