Chapter 5Internet Programming one PHP.pptx

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PHP
Internet Programming
Chapter Five
1 Compiled by Demeke A. Information Systems

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Outlines
Compiled by Demeke A. Information Systems
2
 PHP definition
 Basic syntax of PHP
 Variables
 Comments
 Operators
 Condition statements
 Looping/iteration statements
 Array
 Function
 PHP form and inputs

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Introduction to PHP
 PHP stands for : Hypertext Preprocessor
 PHP is server-side scripting language for creating dynamic and
interactive websites.
 PHP is perfectly appropriate for Web development and can be
embedded directly into the HTML code.
 PHP is often used together with Apache(web server) on various
operating systems.
 A PHP file may contain text, HTML tags and scripts.
3 Compiled by Demeke A. Information Systems

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Introduction to PHP…
4
 Scripts in a PHP file are executed on the server.
 PHP files are returned to the browser as plain HTML
 PHP files have a file extension of ".php", or ".phtml“
 PHP is case sensitive:

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5
 PHP supports many databases (MySQL, Informix, Oracle,
Sybase, Solid, PostgreSQL, Generic ODBC, etc.)
 PHP runs on different platforms (Windows, Linux, Unix,
etc.)
 PHP is compatible with almost all servers used today
(Apache, IIS, etc.)
 PHP is easy to learn and runs efficiently on the server side
Introduction to PHP…

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Basic PHP Syntax
6
 A PHP scripting block always starts with
 <?php and ends with ?>.
 A PHP scripting block can be placed anywhere in the document.
 Each code line in PHP must end with a semicolon.

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Output Statement
7
 There are two basic statements to output text with PHP: echo and print.
 Format
 echo output1, output2, output3, output4,….;
 echo (output);
 Format
 print output;
 print (output);
 Unlike echo print can accept only one argument.
 It is possible to embed html tags into echo and print statement.
 For example - we have used the echo statement to output the text "Hello
World".
<?php
echo "Hello <br>World";
?>

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Comments in PHP
8
 There are two commenting formats in PHP:
 Single-line comments:
 In PHP, we use // to make a single-line comment
 Multi-lines comments:
 We use /* and */ to make a multiple line comment block.
<html>
<body>
<?php
//This is a single-line comment
/*
This is
A multiple line comment
block
*/
?>
</body>
</html>

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PHP Variables
9
 Variables are used for storing values, such as numbers, strings
or function results.
 When a variable is set it can be used many times in a script.
 All variables in PHP start with a $ sign symbol.
 The correct way of setting a variable in PHP:
 $var_name = value;
 $txt = "HelloWorld!";
 In PHP a variable does not need to be declared before being set.
 In PHP the variable is declared automatically when you use it.
 There is no size limit for variables name.

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PHP Variables…
10
 PHP automatically converts the variable to the correct data
type, depending on their value.
 A variable name must start with a letter or an underscore.
 A variable name can consist of numbers, letters, underscores
but you cannot use characters like + , - , % , ( , ) . & , etc
 A variable name should not contain spaces.

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PHP Constants
11
 A constant is a name or an identifier for a simple value.
 A constant value cannot change during the execution of the
script.
 By default a constant name is case-sensitive.
 By convention, constant identifiers are always uppercase.
 A constant name starts with a letter or underscore (can be a
combination of letters, numbers, or underscores.)
 If you have defined a constant, it can never be changed or
undefined.

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PHP Constants
12
 To define a constant you have to use define() function
 There is no need to write a dollar sign ($) before a constant.
 To retrieve the value of a constant, you can simply specifying its
name.
 You can also use the function constant() to read a constant's value
 Constant example:
<?php
define("MINSIZE", 50);
echo MINSIZE;
echo constant("MINSIZE"); // same thing as the previous line
?>

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PHP Operator Types
13
 What is Operator?
 For example in the expression 4 + 5 = 9.
 Here 4 and 5 are called operands and + is called operator.
 PHP language supports following type of operators.
 Arithmetic Operators
 Comparision Operators
 Logical Operators
 Assignment Operators
 Conditional (or ternary) Operators

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Arithmetic Operators
14
Operator Description Example
A=10, B=20
+ Adds two operands A + B will give 30
- Subtracts second operand from the first A - B will give -10
* Multiply both operands A * B will give 200
/ Divide numerator by denumenator B /A will give 2
% Modulus Operator and return
remainder of an integer division
B %A will give 0
++ Increment operator, increases integer
value by one
A++ will give 11
-- Decrement operator, decreases integer
value by one
A-- will give 9

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Comparison Operators
15
A=10, B=20
== Checks if the value of two operands are equal or not, if yes
then condition becomes true.
(A == B) is not
true.
!= Checks if the value of two operands are equal or not, if values
are not equal then condition becomes true.
(A != B) is true.
> Checks if the value of left operand is greater than the value of
right operand, if yes then condition becomes true.
(A > B) is not true.
< Checks if the value of left operand is less than the value of right
operand, if yes then condition becomes true.
(A < B) is true.
>= Checks if the value of left operand is greater than or equal to
the value of right operand, if yes then condition becomes true.
(A >= B) is not
true.
<= Checks if the value of left operand is less than or equal to the
value of right operand, if yes then condition becomes true.
(A <= B) is true.

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Logical Operators
16
X=6, y=3
&& Called LogicalAND operator.
If both the operands are true then then condition
becomes true.
(x < 10 && y > 1)
returns true
|| Called Logical OR Operator.
If any of the two operands areTrue then then
condition becomes true.
(x==5 || y==5)
returns false
! Called Logical NOT Operator.
Use to reverses the logical state of its operand.
If a condition is true then Logical NOT operator
will make false.
!(x==y) returns
true

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Assignment Operators
17
= Assigns values from right side operands to left side operand C = A + B
+= It adds right operand to the left operand and assign the result to
left operand
C += A is
equivalent to C
= C + A
-= It subtracts right operand from the left operand and assign the
result to left operand
C -= A is equivalent
to C = C - A
*= It multiplies right operand with the left operand and assign the
C *= A is equivalent
to C = C * A
/= It divides left operand with the right operand and assign the
C /= A is
equivalent to
C = C / A
%= It takes modulus division of two operands and assign the result to
left operand
C %= A is
equivalent to
C = C % A

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Conditional Operator
18
 This first evaluates an expression for a true or false value and
then execute one of the two given statements depending
upon the result of the evaluation.
? : Conditional Expression If Condition is true ?Then value
X : Otherwise valueY

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Precedence of PHP Operators
19
Category Operator Associatively
Unary ! ++ -- Right to left
Multiplicative * / % Left to right
Additive + - Left to right
Relational < <= > >= Left to right
Equality == != Left to right
LogicalAND && Left to right
Logical OR || Left to right
Conditional ?: Right to left
Assignment = += -= *= /=
 Operator precedence determines the grouping of terms in an expression.
 This affects how an expression is evaluated.
 Here operators with the highest precedence appear at the top of the table,
those with the lowest appear at the bottom.
 Within an expression, higher precedence operators will be evaluated first.

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PHP Decision Making
20
 You can use conditional statements in your code to make
your decisions based on the different condition.
 PHP supports following three decision making statements:
 if...else statement - use this statement if you want to execute
a set of code when a condition is true and another if the
condition is false
 else if statement - is used with the if...else statement to
execute a set of code if one of several condition are true.
 switch statement - is used if you want to select one of many
blocks of code to be executed.

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The If...Else Statement
21
 If you want to execute some code if a condition is true and
another code if a condition is false, use the if...else statement.
 Syntax
if (condition)
code to be executed if condition is true;
else
code to be executed if condition is false;

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Example
22
<html>
<body>
<?php
$d=date("D");
if ($d=="Fri")
echo "Have a nice weekend!";
else
echo "Have a nice day!";
?>
</body>
</html>

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The If...Else Statement…
23
 If more than one line should be executed if a condition is true/false, the lines
should be enclosed within curly braces:
<html>
<body>
<?php
$d=date("D");
if ($d=="Fri")
{
echo "Hello!<br />";
echo "See you on Monday!";
}
?>
</body>
</html>

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The Else If Statement
24
 If you want to execute some code if one of several conditions
are true use the else if statement
 Syntax
if (condition)
else if (condition)
else
code to be executed if condition is false;

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Example
25
 The following example will output "Have a nice weekend!" if the current day is
Friday, and "Have a nice Sunday!" if the current day is Sunday. Otherwise it will
output "Have a nice day!":
<html>
<body>
<?php
$d=date("D");
if ($d=="Fri")
else if ($d=="Sun")
echo "Have a nice Sunday!";
else
echo "Have a nice day!";
?>
</body>
</html>

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The Switch Statement
26
 If you want to select one of many blocks of code to be executed, use
the Switch statement.
 Syntax
switch (expression)
{
case label1:
code to be executed if expression = label1;
break;
case label2:
code to be executed if expression = label2;
break;
default:
code to be executed by defoult;
}

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Example
27
<html>
<body>
<?php
$d=date("D");
switch ($d)
{
case "Mon":
echo "Today is Monday"; break;
case "Tue":
echo "Today isTuesday"; break;
case "Wed":
echo "Today isWednesday"; break;
case "Thu":
echo "Today isThursday"; break;
case "Fri":
echo "Today is Friday"; break;
case "Sat":
echo "Today is Saturday"; break;
case "Sun":
echo "Today is Sunday"; break;
default:
echo "Wonder which day is this ?";
}
?>
</body>
</html>

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PHP Loop Types
28
 Loops in PHP are used to execute the same block of code a
specified number of times.
 PHP supports following four loop types.
 for - loops through a block of code a specified number of times.
 while - loops through a block of code as long as a specified condition
is true.
 do...while - loops through a block of code once, and then repeats the
loop as long as a specified condition is true.
 for each - loops through a block of code for each element in an array.
 We will discuss about continue and break keywords used to control
the loops execution.

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The for loop statement
29
 The for statement is used when you know how many times
you want to execute a statement or a block of statements.
 Syntax
for (initialization;condition;increment)
{
code to be executed;
}

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Example
30
 The following example makes five iterations and changes the assigned value of two
variables on each pass of the loop:
<html>
<body>
<?php
$a = 0;
$b = 0;
for( $i=0; $i<5; $i++ )
{
$a += 10;
$b += 5;
}
echo ("At the end of the loop a=$a and b=$b" );
?>
</body>
</html>
This will produce following result:
At the end of the loop a=50 and b=25

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The while loop statement
31
 The while statement will execute a block of code if and as long as
a test condition is true.
 If the test condition is true then the code block will be executed.
 the loop will continue until the test condition is found to be false.
 Syntax
while (condition)
{
}

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Example
32
 This example decrements a variable value on each iteration of the loop and the
counter increments until it reaches 10 when the evaluation is false and the loop ends.
<html>
<body>
<?php
$i = 0;
$num = 50;
while( $i < 10)
{
$num--;
$i++;
}
echo ("Loop stopped at i = $i and num = $num" );
?>
</body>
</html>

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The do...while loop statement
33
 The do...while statement will execute a block of code at least
once - then it will repeat the loop as long as a condition is
true.
 Syntax
do
{
}
while (condition);

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Example
34
<html>
<body>
<?php
$i = 0;
$num = 0;
do
{
$i++;
}
while( $i < 10 );
echo ("Loop stopped at i = $i" );
?>
</body>
</html>

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The for each loop statement
35
 The for each statement is used to loop through arrays.
 For each pass the value of the current array element is
assigned to $value and the array pointer is moved by one and
in the next pass next element will be processed.
 Syntax
foreach (array as value)
{
}

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Example
36
<html>
<body>
<?php
$array = array( 1, 2, 3, 4, 5);
foreach( $array as $value )
{
echo "Value is $value <br />";
}
?>
</body>
</html>

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The break statement
37
 The PHP break keyword is used to terminate the execution
of a loop prematurely.
 The break statement is placed inside the loop statement
block.Whenever you want to exit from the loop you can
come out using a break statement.
 After coming out of a loop immediate statement to the loop
will be executed.

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Example
38
 In the following example condition test becomes true when the counter value reaches 3 and loop
terminates.
<html>
<body>
<?php
$i = 0;
while( $i < 10)
{
$i++;
if( $i == 3 )
break;
}
echo (“Loop stopped at i = $i" );
?>
</body>
</html>
Loop stopped at i = 3

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The continue statement
39
 The PHP continue keyword is used to halt the current
iteration of a loop but it does not terminate the loop.
 Just like the break statement the continue statement is placed
inside the loop statement block, preceded by a conditional
test.
 For the pass encountering continue statement, the rest of the
loop code is skipped and next pass starts.

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Example
40
 In the following example loop prints the value of array but for which
condition becomes true it just skip the code and next value is printed.
<html>
<body>
<?php
$array = array( 1, 2, 3, 4, 5);
for each( $array as $value )
{
if( $value == 3 )
continue;
}
?>
</body>
</html>
This will produce following result
Value is 1
Value is 2
Value is 4
Value is 5

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PHP Arrays
41
 An array is a data structure that stores one or more similar type of
values in a single variable.
 For example if you want to store 100 numbers then instead of
defining 100 variables its easy to define an array of 100 length.
 There are three different kind of arrays and each array value is
accessed using array index.
 Numeric array - An array with a numeric index.
 Associative array - An array with strings as index.
 Multidimensional array - An array containing one or more
arrays and values are accessed using multiple indices.

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Numeric Array
42
 These arrays can store numbers, strings and any object but their index will be
represented by numbers.
 By default array index starts from zero.
 Use array() function to create array.
 Example showing how to create and access numeric arrays.
<html>
<body>
<?php
/* First method to create array. */
$numbers = array( 1, 2, 3, 4, 5);
foreach( $numbers as $value )
{
}
?>
</body>
</html>
Value is 1
Value is 2
Value is 3
Value is 4
Value is 5

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Numeric Array…
43
 Second method to create array.
<html>
<body>
<?php
$numbers[0] = "one";
$numbers[1] = "two";
$numbers[2] = "three";
$numbers[3] = "four";
$numbers[4] = "five";
foreach( $numbers as $value )
{
}
?>
</body>
</html>
Value is one
Value is two
Value is three
Value is four
Value is five

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Associative Arrays
44
 The associative arrays are very similar to numeric arrays in term
of functionality but they are different in terms of their index.
 Associative array will have their index as string so that you can
establish association between key and values.
 For example:-To store the salaries of employees in an array, you
can use the employees names as the keys and the value would be
their respective salary.
 NOTE: Don't keep associative array inside double quote while
printing otherwise it would not return any value.

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Example
45
<html>
<body>
<?php
/* First method to create associate array. */
$salaries = array(
"mohammad" => 2000,
“kadir" => 1000,
"zara" => 500
);
echo "Salary of mohammad is ". $salaries['mohammad'] . "<br />";
echo "Salary of kadir is ". $salaries[‘kadir']. "<br />";
echo "Salary of zara is ". $salaries['zara']. "<br />";
?>
</body>
</html>
Output
Salary of mohammad is 2000
Salary of kadir is 1000
Salary of zara is 500

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Second method to create an associative array
46
<html>
<body>
<?php
$salaries['mohammad'] = "high";
$salaries['qadir'] = "medium";
$salaries['zara'] = "low";
echo "Salary of mohammad is ". $salaries['mohammad'] . "<br />";
echo "Salary of qadir is ". $salaries['qadir']. "<br />";
echo "Salary of zara is ". $salaries['zara']. "<br />";
?>
</body>
</html>
Output
Salary of mohammad is high
Salary of qadir is medium
Salary of zara is low

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Multidimensional Arrays
47
 In multi-dimensional array each element in the main array
can also be an array.
 And each element in the sub-array can be an array, and so on.
 Values in the multi-dimensional array are accessed using
multiple index.
Example
 In this example we create a two dimensional array to store
marks of three students in three subjects:
 This example is an associative array, you can create numeric
array in the same fashion.

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Example
48
<html>
<body>
<?php
$marks = array(
“Ali" => array
(
"physics" => 35,
"maths" => 30,
"chemistry" => 39
),
“kadir" => array
(
"physics" => 30,
"maths" => 32,
"chemistry" => 29
),
"zara" => array
(
"physics" => 31,
"maths" => 22,
"chemistry" => 39
)
);
/*Accessing multi-dimensional array values */
echo "Marks forAli in physics : " ;
echo $marks[‘Ali']['physics'] . "<br />";
echo "Marks for qadir in maths : ";
echo $marks[‘kadir']['maths'] . "<br />";
echo "Marks for zara in chemistry : " ;
echo $marks['zara']['chemistry'] . "<br />";
?>
</body>
</html>


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Compiled by Demeke A. Information
Systems
String Operation
49
 String Concatenation Operator
 To concatenate two string variables together, use the dot (.)
operator:
<?php
$string1="HelloWorld";
$string2="1234";
echo $string1 . " " . $string2;
?>
 This will produce following result:
HelloWorld 1234

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Systems
Using the strlen() function
50
 The strlen() function is used to find the length of a string.
 Let's find the length of our string "Hello world!":
<?php
echo strlen("Hello world!");
?>
 This will produce following result: 12
 The length of a string is often used in loops or other
functions, when it is important to know when the string
ends.

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Systems
Using the strpos() function
51
 The strpos() function is used to search for a string or character within a
string.
 If a match is found in the string, this function will return the position of
the first match.
 If no match is found, it will return FALSE.
 Example lets find the string "world" in Hello world string:
<?php
echo strpos("Hello world!","world");
?>
 This will produce following result: 6
 As you see the position of the string "world" in our string is position 6.
 The reason that it is 6, and not 7, is that the first position in the string is 0, and
not 1.

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Systems
PHP Functions
52
 A function is a block of code that can be executed whenever
we need it.
Creating PHP functions:
 All functions start with the word "function()"
 Name the function - It should be possible to understand what
the function does by its name.
 The name can start with a letter or underscore (not a number)
 Add a "{" –The function code starts after the opening curly brace
 Insert the function code
 Add a "}" -The function is finished by a closing curly brace

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Systems
Function Example
53
<html>
<head>
<title>Writing PHP Function</title>
</head>
<body>
<?php
/* Defining a PHP Function */
function writeMessage()
{
echo "You are really a nice person, Have a nice time!";
}
/* Calling a PHP Function */
writeMessage();
?>
</body>
</html>

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Systems
Function Example…
54
A simple function that writes a name when it is called:
<html>
<body>
<?php
function writeMyName()
{
echo “abebe ali";
}
writeMyName();
?>
</body>
</html>

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PHP Functions with Parameters:
55
 PHP gives you option to pass your parameters inside a function.
 You can pass any number of parameters your like.
 These parameters work like variables inside your function.
 Following example takes two integer parameters and add them
together and then print them.
<?php
function addFunction($num1, $num2)
{
$sum = $num1 + $num2;
echo "Sum of the two numbers is : $sum";
}
addFunction(10, 20);
?>

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Example
56
<html>
<body>
<?php
function writeMyName($fname)
{
echo “$fname <br />";
}
echo "My name is ";
writeMyName(“abebe");
?>
</body>
</html>

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PHP Functions - Return values
57
 A function can return a value using the return statement in conjunction with a value or
object .
 Return stops the execution of the function and sends the value back to the calling code.
 Example
<html>
<body>
<?php
function add($x,$y)
{
$total = $x + $y;
return $total;
}
echo "1 + 16 = " . add(1,16)
?>
</body>
</html>
The output of the
code will be:
1 + 16 = 17

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Passing Arguments by Reference
58
 It is possible to pass arguments to functions by reference.
 This means that a reference to the variable is manipulated by
the function rather than a copy of the variable's value.
 Any changes made to an argument in these cases will change
the value of the original variable.
 You can pass an argument by reference by adding an
ampersand to the variable name in the function definition.

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Example
59
<html>
<head>
<title>Passing Argument by Reference</title>
</head>
<body>
<?php
function addFive(&$num)
{
$num += 5;
}
function addSix(&$num)
{
$num += 6;
}
$orignum = 10;
addFive( $orignum );
echo "OriginalValue is $orignum<br />";
addSix( $orignum );
echo "OriginalValue is $orignum<br />";
?>
</body>
</html>
Output
OriginalValue is 15
OriginalValue is 21

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Setting Default Values for Function Parameters:
60
 You can set a parameter to have a default value if the function's caller doesn't pass it.
 Following function prints “no test “ in case the we does not pass any value to this
function.
<html>
<head>
<title>Writing PHP Function which returns value</title>
</head>
<body>
<?php
function printMe($param = “No test”)
{
print $param;
}
printMe("This is test");
printMe();
?>
</body>
</html>
Output
This is test
No test

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PHP Forms and User Input
61
 The PHP $_GET and $_POST variables are used to retrieve information from forms,
like user input.
 The most important thing to notice when dealing with HTML forms and PHP is that
any form element in HTML page will automatically be available to your PHP scripts.
Form example:
<html>
<body>
<form action="welcome.php" method="post">
Name: <input type="text" name="name" />
Age: <input type="text" name="age" />
<input type="submit" />
</form>
</body>
</html>

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PHP Forms and User Input…
62
 The example HTML page above contains two input fields and a
submit button.
 When the user fills in this form and click on the submit button,
the form data is sent to the "welcome.php" file.
 The "welcome.php" file looks like this:
<html>
<body>
Welcome <?php echo $_POST["name"]; ?>.<br />
You are <?php echo $_POST["age"]; ?> years old.
</body>
</html>
Welcome John.
You are 28 years old.

10/22/2024
PHP $_GET
63
 The $_GET variable is used to collect values from a form with
method="get".
 The $_GET variable is an array of variable names and values are
sent by the HTTP GET method.
Example
<form action="welcome.php" method="get">
Name: <input type="text" name="name" />
Age: <input type="text" name="age" />
</form>

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PHP $_GET…
64
 When the user clicks the "Submit" button, the URL sent
could look something like this:
localhost/welcome.php?name=Ax&age=50
 The "welcome.php" file can now use the $_GET variable to
catch the form data
 Note that the names of the form fields will automatically be
the ID keys in the $_GET array:
 Welcome <?php echo $_GET["name"]; ?>.<br />
 You are <?php echo $_GET["age"]; ?> years old!

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Why use $_GET?
65
 Information sent from a form with the GET method is
visible to everyone (it will be displayed in the browser's
address bar)
 So this method should not be used when sending
passwords or other sensitive information!
 Get method has limits on the amount of information to
send
 So it is not suitable on large variable values.

10/22/2024
PHP $_POST
66
 The $_POST variable is used to collect values from a form
with method="post".
 The $_POST variable is an array of variable names and values
are sent by the HTTP POST method.
 Information sent from a form with the POST method is
invisible to others and has no limits on the amount of
information to send.

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Example
67
<form action="welcome.php" method="post">
Enter your name: <input type="text" name="name" />
Enter your age: <input type="text" name="age" />
</form>
 When the user clicks the "Submit" button, the URL will not
contain any form data, and will look something like this:
localhost/welcome.php

10/22/2024
The $_REQUEST Variable
68
 The PHP $_REQUEST variable contains the contents of both
$_GET and $_POST variables.
 The PHP $_REQUEST variable can be used to get the result
from form data sent with both the GET and POST methods.
 Example
Welcome <?php echo $_REQUEST["name"]; ?>.<br />
You are <?php echo $_REQUEST["age"]; ?> years old!

Chapter 5Internet Programming one PHP.pptx

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