lab4_ php basics ii

8/3/2019 Lab4_ PHP Basics II

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ARRAY FUNCTIONSfunction Description Usage

count( ) Returns the number of key-value pairs in an array

count (array)

array_unique( ) Removes duplicates from anarray

array_unique (array)

array_combine( ) Takes one array as keys and oneas values and creates a newarray of key value pairs. Botharrays must have equalelements.

array_combine (array1,array2)

array_merge( ) Merges key-value pairs of two

arrays into a single array

array_merge (array1,

[array2, array3...])array_chunk( ) Divides an array into small

subarrays of specified sizearray_chunk (array, size,[preserve_key])

array_keys( ) Returns an array comprising of keys from input array

array_keys (array, [value])


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ARRAY FUNCTIONS (Contd..)

array_values( ) Returns an array comprising of values from input array

array_values (array)

array_slice( ) Removes specified portion of an array

array_slice (array, start,length, [preserve])

array_splice( ) Removes specified portion of an array and replaces it with

given elements

array_splice (array, start,[length], [array])

array_push( ) Uses array as a stack andinserts a given element at last

array_push (array, value1,[value2...])

array_pop( ) Uses array as a stack and

removes last element

array_pop (array)

list( ) breaks an array apart intoindividual variables.

list (var1, [var2...])


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ARRAY FUNCTION EXAMPLETry this PHP code


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ARRAY FUNCTION EXAMPLE and here is the output of previous code


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FUNCTIONS Functions are a way to group common tasks or calculations

to be re-used easily. Calling a function in PHP:

$result = sum ($a, 5);print('I am human, I am.');

Defining a function in PHP:function add_numbers($x, $y) {

$z = $x + $y;return $z;

} echo is not a function.


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PHP allows you to give parameters default values whendeclaring the function.

function print__strings ($var1 = "Hello World", $var2 ="I'm Learning PHP"){

echo($var1);

echo("\n");echo($var2);

}

Function Call : print_strings("hello"); Output :

hello

I'm Learning PHP

FUNCTIONS


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Another way to have a dynamic number of parameters is touse PHP's built-in func_num_args , func_get_args , and

func_get_arg functions.function mean( ){

$sum = 0;$param_count = func_num_args();for ($i = 0; $i < $param_count; $i++)

$sum += func_get_arg($i);$mean = $sum / $param_count;echo "Mean: {$mean}";return NULL;

}

FUNCTIONS (Contd)


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If you want to return multiple variables you need toreturn an array rather than a single variable. For example:

function maths ($x, $y)

{$z = $x + $y ;$w = $x - $y ;

$ret = array ("tot"=>$z, "diff"=>$w);return $ret;

} When calling this from your script you need to call it intoan array.

$return = maths (10, 5);$return['tot'] will be the total 15, while $return['diff'] will be thedifference 5 in above case.

FUNCTIONS (Contd)


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Try this PHP code to get familiar with functions.


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HTML FORM ELEMENT

INTERACTION The PHP script running at server, receives the data from the

form and uses it to perform an action such as updatingdatabase contents, sending database format, user authenticationetc.

To create a form and point it to a PHP document, the HTMLtag is used and an action is specified as follows:

All fields in the form are stored in the variables $_GET or$_POST, depending on the method used to submit the form.The difference between the GET and POST methods is

that GET submits all the values in the URL, while POSTsubmits values transparently through HTTP headers.


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PHP Code that handles the previousform:


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EX: CHECK BOXES & MULTILISTS


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PHP Code that handles the previous form:


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SESSION It is basically a temporary set of variables whose values

persist across subsequent web pages.

Session objects exist until: User closes the browser window Sessions maximum time allotment is exceeded Using PHP function such as session_destroy() is called.

Every session is assigned a unique session ID, which keepsall the current information together. Session ID can bepassed through the URL or through the use of cookies.

Session functions: session_start( ) and session_destroy( ) $_SESSION[ ]: PHP super global array variable that

contains currently registered to a script's session


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SESSION EXAMPLEThis PHP scripts displays the number of times a user has accessedthis page


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SESSION EXAMPLE and here is the output of the previous script:


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Save this file asfriends.php

AUTHENTICATION THROUGH

SESSION (Contd)


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AUTHENTICATION THROUGHSESSION (Contd)

You will find following output if session is valid:


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COOKIES A cookie is a small piece of information given

to a Web browser by a Web server. The browserstores the information in a text file. Thisinformation is then sent back to the server eachtime the browser requests a page from theserver.

Cookies can live on a clients computer for aslong as a developer has decided it to remain.

This means unlike sessions, if you closebrowser, cookies can remain in your computer.

Continued


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COOKIE Example 1Output : Initially or after 30 seconds

Output : After first attempt and before 30 seconds elapsed


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COOKIE Example 2By setting cookie your username will be remembered andyou need not have to type username again.Save this file as cookie_request.php


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COOKIE Example 1Save this file as cast_my_vote.php


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COOKIE Example 2

You will have following output if cookie is found :

lab4_ php basics ii

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