Programming Basics - array, loops, funcitons

TRIVUz Academy

PF03
Class Id:

Programming Fundamentals
MS Alam TRIVUz
Founder, TRIVUz Network
TRIVUz Academy

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Recap PF01 & PF02

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Recap
We Define Computer & Programming

Programming Process

Programming Language

Inputs & Outputs

Define Logical Processing

Variables

Data Types

Define Conditional Statement
If… Then… Else…
TRIVUz Academy PHP Operators

www.trivuzacademy.com

We are going to learn
Variable+

Array

Array Functions

Global Array

Loop

for, do…while, for each

Functions


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www.trivuzacademy.com

Variable+
Array

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Array
What is an Array?
A variable is a storage area holding a number or
text. The problem is, a variable will hold only one
value.

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Array
What is an Array?
A variable is a storage area holding a number or
text. The problem is, a variable will hold only one
value.
An array is a special variable, which can store
multiple values in one single variable.

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Array
What is an Array?
• An array in PHP is a structure which maps keys
(array element names) to values
• The keys can specified explicitly or they can be
omitted
• If keys are omited, integers starting with 0 are
keys
• The value mapped to a key can, itself, be an
array, so we can have nested arrays

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Array
What is an Array?
Variable VS Array

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Array
What is an Array?
Variable VS Array?
In Variable:
<?php

$student = “Farah”;

$student = “Tawhid”;

$student = “Jewel”;

?>

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Array
What is an Array?
Variable VS Array?
In Array:
<?php

$student = array(“Farah”,”Tawhid”,”Jewel”);

?>

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Array
What is an Array?
Variable VS Array?
Array will create Variable index like
$student[0] = “Farah”;

$student[1] = “Tawhid”;

$student[2] = “Jewel”;

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Array
Very simple array and output

Code
<?php

$student = array(“Farah”,”Tawhid”,”Jewel”);

print_r($student);

?>

Output
Array ( [0] => Trivuz [1] => Tawhid [2] => Jewel )

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Array
Echo value from array

Code
<?php

echo $student[0];
echo $student[1];
?>

Output
Farah
Tawhid

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Array
Change Value in Array

Code
<?php
$student[0] = ”Trivuz”;
$student[2] = "Asif Islam”;
print_r($student);
?>

Output
Array ( [0] => Trivuz[1] => Tawhid [2] => Asif Islam )

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Array
Specifying an Array
• A special function is used to specify arrays
array()

• Format of Usage
array([key=>]value, …)

• A key is either a string or a non-negative integer

• A value can be anything

• Format of associative array specification
$ages = array(“Huzaifa”=>22, “Tuhin”=>23)

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Array
Specifying an Array
• Here is another associative (hash) array:
$ages[„Riaydh‟]=“24”;
$ages[„Piash‟]=“21”;

• Implicit indices are integers, starting at 0
$student = array(“Koushik”,”Tafsir”,”Eunus”);

• Here is the same array written differently
$student[0] = “Koushik”;
$student[0] = “Tafsir”;
$student[0] = “Eunus”;

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Array
Specifying an Array
• If and explicit integer index is followed by
implicit indices, they follow on from the highest
previous index
• Here is an array indexed by integers 1,2,3
$student = array(1=>“Avishek”,”Mehedi”,”Masud”);

• Here is an array indexed by integers 1,5,6
$student = array(5=>“Avishek”,1=>”Mehedi”,”Masud”);

• Show output
<?php
print_r($student);
?>

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Array
Specifying an Array
• A two-dimensional hash array
$result = array(“Farah“=>array(“Bangla”=>85,”English”=>78));

echo $result[„Farah‟][„Bangla];
echo $result[„Farah‟][„English‟];

• A two-dimensional ordinary array
$heights = array(10,20,30,40,50),array(100,200));

echo $heights[0][1]; // output : 20
echo $heights[1][1]; // output : 200

• Change a two-dimensional array value
$heights[0][0] = 130;
$heights[0][1] = 140;
print_r($heights); // output : Array ( [0] => Array ( [0] => 130 [1] => 140 ) )

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Array Functions
PHP provides a huge set of array-manipulation functions
 array – Create an array
 array_change_key_case – Returns an array with all string keys
lowercased or uppercased
 array_chunk – Split an array into chunks
 array_count_values – Counts all the values of an array
 array_diff – Computes the difference of arrays
 array_filter – Filters elements of an array using a callback funciton
 array_flip – Flip all the values of an array
 array_fill – Fill and array with values
 array_intersect – Computes the intersection of arrays
 array_key_exists – Checks if the given key or index exists in the
array
 array_keys – Return all the keys of an array

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Array Functions
 array_map – Applies the callback to the elements of the given
arrays
 array_merge – Merge two or more arrays
 array_merge_recursive – Merge two or more arrays recursively
 array_multisort – Sort multiple or multi-dimensional arrays
 array_pad – Pad array to the specified length with a value
 array_pop – Pop the element off the end of array
 array_push – Push one or more elements onto the end of array
 array_rand – Pick one or more random entries out of an array
 array_reverse – Return an array with elements in reverse order
 array_reduce – Iteratively reduce the array to a single value using
a callback function
 array_shift – Shift an element off the beginning of array
 array_slice – Extract a slice of the array
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Array Functions
 array_splice – Remove a portion of the array and replace it with
something else
 array_sum – Calculate the sum of values in an array
 array_unique – Remove duplicate values from an array
 array_unshift – Prepend one or more elements to the beginning of
array
 array_values – Return all the values of an array
 array_walk – Apply a user function to every member of an array
 arsort – Sort an array in reverse order and maintain index
association
 asort – Sort an array and maintain index association
 compact – Create array containing variables and their values
 count – Count element in a variable
 current – Return the current element in an array
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Array Functions
 each – Return the current key and value pair from an array and
advance the array cursor
 end – Set the internal pointer of an array to its last element
 extract – Import variables into the current symbol table from an
array
 in_array – Return TRUE if a value exists in an array
 Array_search – Searches the array for a given value and returns
the corresponding key if successful
 key – Fetch a key from an associative array
 krsort – Sort an array by key
 list – Assign variables as if they were an array
 natsort– Sort an array using a “natural order” algorithm
 pos – Get the current element from an array
 prev – Rewind the internal array pointer
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Array Functions
 range – Create an array containing a range of elements
 reset – Set the internal pointer of an array to its first element
 rsort – Sort an array in reverse order
 shuffle – Shuffle an array
 sizeof – Get the number of elements in variable
 sort – Sort an array
 uasort – Sort an array with a user-defined comparison function
 uksort – Soft an array by keys using a user-defined comparison
function
 usoft– Soft an array by values using a user-defined comparison
function

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Global Array
Global Arrays
 PHP Creates 6 global arrays that contain EGPCS (ENVIRONMENT,
GET, POST, COOKIES and SERVER) information
 PHP also creates a variable called $_REQUEST that contains all the
information in the 6 global arrays
 PHP also creates a variable called $PHP_SELF that contains the
name of the current script (relative to the doc root)
 $_ENV – Contains the values of any environment variables, such as
the browser version
 Eg: $_ENV[HTTP_USER_AGENT]

 $_FILES – Contains information about any files submitted
 $_COOKIES – Contain any cookies submitted as name value pairs
 $_SERVER – Contains useful information about the webserver

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Global Array
$_SERVER Keys
 [DOCUMENT_ROOT]  [SERVER_SOFTWARE]
 [HTTP_*]  [COMSPEC]
 [PHP_SELF]  [GATEWAY_INTERFACE]
 [QUERY_STRING]  [PATHEXT]
 [REMOTE_ADDR]  [PATH]
 [REQUEST_METHOD]  [REMOTE_PORT]
 [REQUEST_URI]  [SERVER_ADDR]
 [SCRIPT_FILENAME]  [SERVER_ADMIN]
 [SCRIPT_NAME]  [SERVER_SIGNATURE]
 [SERVER_PORT]  [SystemRoot]
 [SERVER_PROTOCOL]  [WINDIR]

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Control Structure
Looping

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Control Structure
Looping

 Loops execute a block of code a specified number of
times, or while a specified condition is true.

 PHP loops are control structures and you can use
them the execute a code block more times. It means
you don't have to copy and paste your code many
times in the file just use a right loop statement.

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Control Structure
Looping
A basic example:
<?php
echo " 1 ”;
echo " 2 ”;
echo " 3 ”;
echo " 4 ”;
echo " 5 ”;
?>

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Control Structure
Looping
A basic example:
<?php
echo " 1 ”;
echo " 2 ”;
echo " 3 ”;
echo " 4 ”;
echo " 5 ”;
?>

With a for loop it looks like this:
<?php
for ($i=1; $i <= 5; $i++) {
echo “ $i “;
}
?>
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Control Structure
Looping

 In PHP, we have the following looping statements:
 While
 Do…while
 For
 foreach

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Control Structure
while loop
Syntax

while

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Control Structure
while loop
Syntax

while (condition)

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Control Structure
while loop
Syntax

while (condition)
{
// code to be executed;
}

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Control Structure
while loop
Example

<?php

$i = 1;
while ($i < 5)
{
echo “ I = “ . $i . “ ”;
echo $i++;
}

?>

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Control Structure
while loop
Execution
Code:
<?php
$i = 1;
while ($i < 5)
{
echo “ Value of I is now “ . $i . “ ”;
echo $i++;
}
?>

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Control Structure
while loop
Execution (Loop - 1)
Code:
<?php
$i = 1;
while ($i < 5) // $i is now 1
{
echo $i++; // $i is now 2
}
?>

Output:
Value of I is now 1

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Control Structure
while loop
Code:
<?php
$i = 1;
{
}
?>

Output:
Value of I is now 1
Value of I is now 2

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Control Structure
While Loop
Code:
<?php
$i = 1;
{
}
?>

Output:
Value of I is now 1
Value of I is now 2
Value of I is now 3

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Control Structure
while loop
Code:
<?php
$i = 1;
{
}
?>

Output:
Value of I is now 1
Value of I is now 2
Value of I is now 3
Value of I is now 4

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Control Structure
while loop
Code:
<?php
$i = 1;
{
echo $i++; // not executed
}
// next code to execute
?>
Output:
Value of I is now 1
Value of I is now 2
Value of I is now 3
Value of I is now 4

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Control Structure
do…while loop
Syntax

do {
}
while (condition);

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Control Structure
do…while loop
Example

do {
$i++;
echo “The number is “ . $i . “ ”;
}
while ($i < 5);

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Control Structure
for loop
Syntax

for (init; condition; increment)

{

}

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Control Structure
for loop
Example

for ($i = 1; $i < 5; $++)

{
echo “Current value of I is “ . $i . “ ”;

}

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Control Structure
for each

FOREACH is used in PHP to loop over all elements of an array. The basic
syntax of FOREACH is as follows:
FOREACH ($array_variable as $value)
{
//code to execute
}

or

FOREACH ($array_variable as $key => $value)
{
//code to execute
}

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Control Structure
for each
Simple Syntax

foreach (array_expression as $value)

// statement

foreach (array_expression as $key => $value)

// statement

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Control Structure
for each
Example

<?php

$arr = array(1, 2, 3, 4);

foreach ($arr as &$value) {

$value = $value * 2;

}

// $arr is now array(2, 4, 6, 8)

unset($value); // break the reference with the last element

?>

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Control Structure
for each
Example

<?php
$arr = array("one", "two", "three");
reset($arr);
while (list(, $value) = each($arr)) {
echo "Value: $value n”;
}
foreach ($arr as $value) {
echo "Value: $value n”;
}
?>

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Function

What is function?

How function help programmers?

Types of function

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Function

System Defined Function

User Defined Function

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Function
User-Defined Function

In PHP, functions are defined in the following fashion:

function function_name ([variable [= constant][,…])
{

// any valid PHP code

}

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Function

Example: User-Defined Function to determine a Leap Year

<?php

function is_leapyear ($year = 2011)
{

$is_leap = (!($year % 4) && (($year % 100) || !($year % 400)));

return $is_leap;

}

?>

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Function

Function with user defined argument

function function_name ($arg)
{

// any valid PHP code

}

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Function


<?php
function is_leapyear ($year)
{


return $is_leap;

}

?>

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Function


<?php
function is_leapyear ($year)
{


return $is_leap;

}

?>
Calling the user defined function is_leapyear

Is_leapyer(2008);
Is_leapyer(2011);
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Thank You

MS Alam TRIVUz
Founder,
TRIVUz Academy
trivuz@gmail.com

Programming Basics - array, loops, funcitons

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