Working with Data and built-in functions of PHP

Working with Data Ms. Mohana Priya S Department of computer Science[UG]

Validate input field in the HTML Form • To validate the form using HTML, we will use the HTML <input> required attribute. • The <input> required attribute is a Boolean attribute that is used to specify the input element that must be filled out before submitting the Form.

Data validation ensures accurate and useful user input. It checks for completed required fields, valid dates, and appropriate data types. • Required Fields: Users must fill in all mandatory fields to avoid incomplete submissions. • Date Validation: Ensures users enter dates in the correct format. • Numeric Field Text: Verifies users enter text in text fields and numeric values in numeric fields.

Validation takes place either on the server side (after data submission) or on the client side (prior to data submission). • Server-side: Done by the web server for data integrity and security. • Client-side: Performed by the browser for instant user feedback.

<form action="#"> <label for="fname">First Name:</label> <input type="text" name="fname" id="fname" required> <label for="lname">Last Name:</label> <input type="text" name="lname" id="lname" required> <label for="email">Email Id:</label> <input type="email" name="email" id="email" required> <input type="submit" value="Submit"> </form>

<label for="phone">Phone:</label> <input type="number" id="phone" name="phone" pattern="[0-9]{10}" placeholder="Enter 10-digit mobile number" required>

Passing variables with data between pages

Pass values of variables between pages in site. These are required in many different ways. Some time we collect some value from a database and want to retain the value for the particular user throughout the site as the user moves between pages. There are different ways for passing such values of the variables.

Passing variable values between pages using session This is one of the secured ways the variables are passed between pages. The best example of such a system is when we see our user- id inside a member area after we logged in. In a member login system the user details are verified and once found correct, a new session is created and with user id of the member and this value is stored at server end. Every time a new page is opened by the browser, the server checks the associated session value and display the user id. This system is more secure and the member doesn't get any chance to change the values.

Passing variables between pages using cookies Cookies are stored at the user or the client end and values can be passed between pages using PHP. But here the client browser can reject accepting cookies by changing the security settings of the browser. So this system can fail to pass values between pages if user or client end settings are changed. But cookies are quit useful in handling user entered values and passing them between pages.

Passing variables between pages using URL Pass variable values between pages through the URL ( in address bar of the browser). Here values are visible to the user and others as they appear in the address bar and also in the browser history. This is not a secure way to transfer sensitive data like password, etc.

Advantage of using URL to pass variables • The advantage is we can pass data to a different site even running at different servers. Any scripting language like ASP, JSP, PHP • Easy to save the URL or bookmark it for frequent use. • Copy the URL and send it to a friend to refer.

Example of passing data through URL within a site. <a href='page2.php?id=2489&user=tom'>link to page2</a> When the above link is clicked, page2.php gets the variables id and user with data 2489 and tom respectively. Code to collect data in PHP. echo $_GET['id']; // output 2489 echo $_GET['user']; // output tom

Passing data outside <a href=https://www.sitename.com/index.php?id=2489&user=tom>Link to another site</a> Note that after the page name we are using question mark ( ? ) to start the variable data pair and we are separating each variable data pair with one ampersand ( & ) mark.

Submitting form values through GET method A web form when the method is set to GET method, it submits the values through URL. So we can use one form to generate an URL with variables and data by taking inputs from the users. The form will send the data to a page within the site or outside the site by formatting a query string. <form method=GET action='https://www.anysite.com/index.php'>

Submitting a form through POST method By post method of form submission we can send more number or length of data. Sensitive information like password does not get exposed in URL by POST method, so our login forms we should use POST method to submit data. This is how we collect data submitted by POST method in PHP $id=$_POST['id']; $password=$_POST['password'];

Difference between GET and POST Issues GET POST Browser History Data remain in Browser History Data Not available in Browser History Bookmark URL with Data can be bookmarked No data is available in URL to bookmark the page Data Length Restriction The restriction (of URL ) is applicable No Restriction cached Can be cached No meaningful caching Sensitive Data Data like password , pin etc. are exposed through URL so they should not be passed using GET method Better than GET method as data is not exposed through URL

Collecting data submitted by either GET or POST method If a page is receiving a data which can come in any one of the method GET or POST then how to collect it ? Here we are not sure how to collect the data. So we will use like this. $id=$_REQUEST['id']; $password=$_REQUEST['password'];

PHP - $_REQUEST $_REQUEST $_REQUEST is a PHP super global variable which contains submitted form data, and all cookie data. In other words, $_REQUEST is an array containing data from $_GET, $_POST, and $_COOKIE. You can access this data with the $_REQUEST keyword followed by the name of the form field, or cookie, like this: $_REQUEST['firstname']

String Function chr() • It is used to return a character from a specified ASCII value • The PHP chr() function is used to generate a single byte string from a number. In another words we can say that it returns a character from specified ASCII value. • Syntax: string chr ( int $bytevalue );

Example 1: <?php $char =52; echo "Your character is :".$char; echo " "."By using 'chr()' function your value is: ".chr($char);// d ecimal Value ?> • Your character is : 52 By using 'chr()' function your value is: 4

Example 2: <?php $char =052; echo "Your character is :".$char; echo " "."By using 'chr()' function your value is: ".chr($char); // O ctal Value ?> • Your character is :42 By using 'chr()' function your value is: *

<?php echo "Your character is :0x52"; echo " "."By using 'chr()' function your value is: ".chr(0x52); // H ex value ?> • Your character is :0x52 By using 'chr()' function your value is: R

ord() • Returns the ASCII value of the first character of a string. Definition and Usage The ord() function returns the ASCII value of the first character of a string. Syntax: ord(string) <?php echo ord("h")." "; echo ord("hello")." "; ?> O/P: 104 104

• strtolower() hello world PHP string functions <?php echo strtolower("HELLO WORLD."); ?>

• strtoupper() • Convert all characters to uppercase: <?php echo strtoupper("Hello WORLD!"); ?> HELLO WORLD

• lcfirst() - converts the first character of a string to lowercase • ucfirst() - converts the first character of a string to uppercase • ucwords() - converts the first character of each word in a string to uppercase

ltrim() - Removes whitespace or other characters from the left side of a string Definition and Usage The ltrim() function removes whitespace or other predefined characters from the left side of a string. Related functions: •rtrim() - Removes whitespace or other predefined characters from the right side of a string •trim() - Removes whitespace or other predefined characters from both sides of a string

• Syntax ltrim(string,charlist) • string Required. Specifies the string to check • charlist Optional. Specifies which characters to remove from the string. If omitted, all of the following characters are remove "0" - NULL "t" - tab "n" - new line "x0B" - vertical tab "r" - carriage return " " - ordinary white space

• Remove newlines (n) from the left side of a string: • <?php $str = "nnnHello World!"; echo "Without ltrim: " . $str; echo " "; echo "With ltrim: " . ltrim($str); ?>

substr() Syntax substr(string,start,length)

<!DOCTYPE html> <html> <body> <?php // Positive numbers: echo substr("Hello world",10)." "; echo substr("Hello world",1)." "; echo substr("Hello world",7)." "; echo " "; // Negative numbers: echo substr("Hello world",-1)." "; echo substr("Hello world",-10)." "; echo substr("Hello world",-4)." "; ?> </body> </html> O/p: d ello world orld d ello world orld <!DOCTYPE html> <html> <body> <?php echo substr("Hello world",6); ?> </body> </html> O/p: world

The strcmp() function compares two strings. • The strcmp() function compares two strings. • Note: The strcmp() function is binary-safe and case-sensitive. • Tip: This function is similar to the strncmp() function, with the difference that you can specify the number of characters from each string to be used in the comparison with strncmp(). Syntax strcmp(string1,string2)

Return Value <!DOCTYPE html> <html> <body> <?php echo strcmp("Hello world!","Hello world!")." "; // the two strings are equal echo strcmp("Hello world!","Hello")." "; // string1 is greater than string2 echo strcmp("Hello world!","Hello world! Hello!")." "; // string1 is less than string2 ?> </body> </html> o/p: 0 7 -7 This function returns: 0 - if the two strings are equal <0 - if string1 is less than string2 >0 - if string1 is greater than string2

strpos() - Search For a Text Within a String • The PHP strpos() function searches for a specific text within a string. If a match is found, the function returns the character position of the first match. If no match is found, it will return FALSE. Example Search for the text "world" in the string "Hello world!": <?php echo strpos("Hello world!", "world"); // outputs 6 ?>

Replace Text Within a String The PHP str_replace() function replaces some characters with some other characters in a string. Example Replace the text "world" with "Dolly": <?php echo str_replace("world", "Dolly", "Hello world!"); // outputs Hello Dolly! ?>

str_word_count() - Count Words in a String The PHP str_word_count() function counts the number of words in a string. Example Count the number of word in the string "Hello world!": <?php echo str_word_count("Hello world!"); // outputs 2 ?>

Math functions •PHP provides many predefined math constants and functions that can be used to perform mathematical operations.

Math functions in PHP • abs() • Ceil() • Floor() • Round() • Fmod() • Min() • Max() • Pow() • Sqrt() • Rand()

Abs() • The abs() function returns the absolute (positive) value of a number. Syntax: abs( value ) Parameters: The abs() function accepts single parameter value which holds the number whose absolute value you want to find. Return Value: It returns the absolute value of the number passed to it as argument. • number Required. Specifies a number. If the number is of type float, the return type is also float, otherwise it is integer

• The abs() function in PHP is identical to what we call modulus in mathematics. The modulus or absolute value of a negative number is positive.

Example • <?php echo(abs(6.7) . " "); echo(abs(-6.7) . " "); echo(abs(-3) . " "); echo(abs(3)); ?> Output • 6.7 6.7 3 3

Ceil() • The ceil() function rounds a number UP to the nearest integer. Syntax: float ceil(value) • Parameters: The ceil() function accepts a single parameter value which represents the number which you want to round up to the nearest greater integer. • Return Value: The return type of the ceil() function is float as shown in the syntax. It returns the number which represents the value rounded up to the next highest integer. • number Required. Specifies the value to round up

Example • Output • 1 1 5 6 -5 -5 • <?php echo(ceil(0.60) . " "); echo(ceil(0.40) . " "); echo(ceil(5) . " "); echo(ceil(5.1) . " "); echo(ceil(-5.1) . " "); echo(ceil(-5.9)); ?>

Floor() • The floor() function rounds a number DOWN to the nearest integer. Syntax: float floor(value) • Parameters: This function accepts the single parameter value which is rounded down to the next lowest integer. • Return Value: The return type is a float value. It returns the next lowest integer value as a float which is rounded down, only if necessary. • number Required. Specifies the value to round down

Example • <?php echo(floor(0.60) . " "); echo(floor(0.40) . " "); echo(floor(5) . " "); echo(floor(5.1) . " "); echo(floor(-5.1) . " "); echo(floor(-5.9)); ?> Output • 0 0 5 5 -6 -6

Round() • The round() function rounds a floating-point number. • Syntax: round(number,precision,mode); • Parameters: It accepts three parameters out of which one is compulsory and two are optional. All of these parameters are described below: • $number: It is the number which you want to round. • $precision: It is an optional parameter. It specifies the number of decimal digits to round to. The default value of this parameter is zero. • $mode: It is an optional parameter. It specifies a constant to specify the rounding mode. • number Required. Specifies the value to round precision • Optional. Specifies the number of decimal digits to round to. Default is 0

• mode Optional. Specifies a constant to specify the rounding mode: PHP_ROUND_HALF_UP - Default. Rounds number up to precision decimal, when it is half way there. Rounds 1.5 to 2 and -1.5 to -2 • PHP_ROUND_HALF_DOWN - Round number down to precision decimal places, when it is half way there. Rounds 1.5 to 1 and -1.5 to -1 • PHP_ROUND_HALF_EVEN - Round number to precision decimal places towards the next even value • PHP_ROUND_HALF_ODD - Round number to precision decimal places towards the next odd value

Example 1 • <?php echo(round(0.60) . " "); echo(round(0.50) . " "); echo(round(0.49) . " "); echo(round(-4.40) . " "); echo(round(-4.60)); ?> • Output • 1 1 0 -4 -5

Example 2 • <?php echo(round(4.96754,2) . " "); echo(round(7.045,2) . " "); echo(round(7.055,2)); ?> • 4.97 7.05 7.06

• <?php echo(round(1.5,0,PHP_ROUND_HALF_UP) . " "); echo(round(-1.5,0,PHP_ROUND_HALF_UP) . " "); echo(round(1.5,0,PHP_ROUND_HALF_DOWN). " "); echo(round(-1.5,0,PHP_ROUND_HALF_DOWN). " "); echo(round(1.5,0,PHP_ROUND_HALF_EVEN) . " "); echo(round(-1.5,0,PHP_ROUND_HALF_EVEN) . " "); echo(round(1.5,0,PHP_ROUND_HALF_ODD) . " "); echo(round(-1.5,0,PHP_ROUND_HALF_ODD)); ?> Example 3 • Output 2 -2 1 -1 2 -2 1 -1

Fmod() • The fmod() function returns the remainder (modulo) of x/y. • In PHP the fmod() function is used to calculate the Modulo of any division which may contain floats as both dividends and divisors. Syntax: float fmod ($dividend, $divisor) • Parameters: The function takes two parameters as follows: • $dividend: This parameter takes a float which is to be divided. • $divisor: This parameter takes a float which is to be used as a divisor. • Return Type: This function returns a Floating-point remainder of the division.

Example • <?php $x = 7; $y = 2; $result = fmod($x,$y); echo $result; ?> Output 1

Min () • The min() function returns the lowest value in an array, or the lowest value of several specified values. • The min() function can take an array or several numbers as an argument and return the numerically minimum value among the passed parameters. The return type is not fixed, it can be an integer value or a float value based on input. • Sytax: min(array_values); or min(value1,value2,...); • Parameters: This function accepts two different types of parameters which are explained below: • array_values : It specifies an array containing the values. • value1, value2, … : It specifies two or more than two values to be compared.

Example • <?php echo(min(2,4,6,8,10) . " "); echo(min(22,14,68,18,15) . " "); echo(min(array(4,6,8,10)) . " "); echo(min(array(44,16,81,12))); ?> Output 2 14 4 12

Max() • The max() function returns the highest value in an array, or the highest value of several specified values. • The max() function of PHP is used to find the numerically maximum value in an array or the numerically maximum value of several specified values. • The max() function can take an array or several numbers as an argument and return the numerically maximum value among the passed parameters. The return type is not fixed, it can be an integer value or a float value based on input. • Sytax: max(array_values); or max(value1,value2,...); • Parameters: This function accepts two different types of arguments which are explained below: • array_values : It specifies an array containing the values. • value1, value2, … : It specifies two or more than two values to be compared.

• <html> <body> <?php echo(max(2,4,6,8,10) . " "); echo(max(22,14,68,18,15) . " "); echo(max(array(4,6,8,10)) . " "); echo(max(array(44,16,81,12))); ?> </body> </html>

Pow() • The pow() function returns ($base raised to the power of $exp. • Syntax: number pow($base, $exp); • Parameters : The pow() function accepts two parameters as shown in the above syntax: • $base : It is used to specify the base. • $exponent : It is used to specify the exponent. • Return Value: It returns a number (integer or floating-point) which is equal to $base raised to the power of $exponent.

<html> <body> <?php echo(pow(2,4) . " "); //16 echo(pow(-2,4) . " ");//16 echo(pow(-2,-4) . " ");//0.0625 ?> </body> </html> Input : pow(3, 2) Output : 9 Input : pow(-3, 2) Output : 9 Input : pow(-3, -3) Output : 0.037037037037037 Input : pow(-3, -3.2) Output : NaN

Sqrt() • The sqrt() function returns the square root of a number. • Syntax: sqrt(number); • number Required. Specifies a number

Example <?php echo(sqrt(0) . " "); // 0 echo(sqrt(1) . " "); // 1 echo(sqrt(9) . " "); // 3 echo(sqrt(0.64) . " "); // 0.8 ?>

Rand() • The rand() function generates a random integer. • The rand() is an inbuilt function in PHP used to generate a random number ie., it can generate a random integer value in the range [min, max]. • rand(); or rand(min,max); • Parameter values: • min: It is an optional parameter that specifies the lowest value that will be returned. The default value is 0. • max: It is an optional parameter that specifies the highest value to be returned. The default value is getrandmax().

Examples: Note: The output of the code may change every time it is run. So the output may not match with the specified output. <?php // Generating a random number $randomNumber= rand(); print_r($randomNumber); print_r("n"); // Generating a random number in a // Specified range. $randomNumber= rand(15,35); print_r($randomNumber); ?> output: 1257424548 28

PHP Array Functions • count, • list, • in_array, • current, • next, • previous, • end, • each

Array() • The array() function is used to create a PHP array. This function can be used to create indexed arrays or associative arrays. PHP arrays could be single dimensional or multi-dimensional. Syntax Syntax to create PHP indexed arrays: $a = array(value1, value2, value3, ...) Syntax to create PHP associative arrays: $a = array(key1 => value1, key2 => value2...)

Example • <?php $cars=array("Volvo","BMW","Toyota"); echo "I like " . $cars[0] . ", " . $cars[1] . " and " . $cars[2] . "."; ?> • I like Volvo, BMW and Toyota.

Count() • The count() function returns the number of elements in an array. Syntax count(array, mode)

in_array — Checks if a value exists in an array • Syntax: • in_array(search, array, type)

in_array example • <?php $people = array("Peter", "Joe", "Glenn", "Cleveland"); if (in_array("Glenn", $people)) { echo "Match found"; } else { echo "Match not found"; } ?> • o/p: Match found

list() function • The list() function is used to assign values to a list of variables in one operation. • Syntax: • list(var1, var2, ...)

Example • <?php $my_array = array("Dog","Cat","Horse"); list($a, , $c) = $my_array; echo "Here I only use the $a and $c variables."; ?> • o/p: Here I only use the Dog and Horse variables.

current() function • Definition and Usage • The current() function returns the value of the current element in an array. • Every array has an internal pointer to its "current" element, which is initialized to the first element inserted into the array.

Related current methods: • end() - moves the internal pointer to, and outputs, the last element in the array • next() - moves the internal pointer to, and outputs, the next element in the array • prev() - moves the internal pointer to, and outputs, the previous element in the array • reset() - moves the internal pointer to the first element of the array • each() - returns the current element key and value, and moves the internal pointer forward Syntax: current(array)

<?php $people = array("Peter", "Joe", "Glenn", "Cleveland"); echo current($people) . " "; // The current element is Peter echo next($people) . " "; // The next element of Peter is Joe echo current($people) . " "; // Now the current element is Joe echo prev($people) . " "; // The previous element of Joe is Peter echo end($people) . " "; // The last element is Cleveland echo prev($people) . " "; // The previous element of Cleveland is Glenn echo current($people) . " "; // Now the current element is Glenn echo reset($people) . " "; // Moves the internal pointer to the first element of the array, which is Peter echo next($people) . " "; // The next element of Peter is Joe print_r (each($people)); // Returns the key and value of the current element (now Joe), and moves the internal pointer forward ?> Peter Joe Joe Peter Cleveland Glenn Glenn Peter Joe Array ( [1] => Joe [value] => Joe [0] => 1 [key] => 1 )

PHP Include File • The include (or require) statement takes all the text/code/markup that exists in the specified file and copies it into the file that uses the include statement. • Including files is very useful when you want to include the same PHP, HTML, or text on multiple pages of a website. • It is possible to insert the content of one PHP file into another PHP file (before the server executes it), with the include or require statement. • The include and require statements are identical, except upon 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

PHP include and require • Including files saves a lot of work. This means that you can create a standard header, footer, or menu file for all your web pages. Then, when the header needs to be updated, you can only update the header include file. Syntax • include 'filename'; or require 'filename';

Advantage • Code Reusability: By the help of include and require construct, we can reuse HTML code or PHP script in many PHP scripts.

PHP include example • PHP include is used to include file on the basis of given path. You may use relative or absolute path of the file. • Let's see a simple PHP include example. Example 1 Assume we have a standard footer file called "footer.php", that looks like this: <?php echo "Copyright © 1999-" . date("Y") . " kristujayanti.edu.in "; ?> To include the footer file in a page, use the include statement: Example <html> <body> <h1>Welcome to my home page!</h1> Some text. Some more text. <?php include 'footer.php';?> </body> </html>

PHP Functions • PHP function is a piece of code that can be reused many times. • It can take input as argument list and return value. • There are thousands of built-in functions in PHP.

Parameterized Function • PHP Parameterized functions are the functions with parameters. You can pass any number of parameters inside a function. These passed parameters act as variables inside your function. • They are specified inside the parentheses, after the function name. • The output depends upon the dynamic values passed as the parameters into the function.

PHP Superglobals PHP provides an additional set of predefined arrays containing variables from the web server the environment, and user input. These new arrays are called superglobals.

$GLOBALS Contains a reference to every variable which is currently available within the global scope of the script. The keys of this array are the names of the global variables.

Example • <?php $x = 75; $y = 25; function addition() { $GLOBALS['z'] = $GLOBALS['x'] + $GLOBALS['y']; } addition(); echo $z; ?> • OUTPUT: 100

$_SERVER • This is an array containing information such as headers, paths, and script locations. • The entries in this array are created by the web server. • There is no guarantee that every web server will provide any of these.

Example • <?php echo $_SERVER['PHP_SELF']; echo " "; echo $_SERVER['SERVER_NAME']; echo " "; echo $_SERVER['HTTP_HOST']; echo " "; echo $_SERVER['HTTP_REFERER']; echo " "; echo $_SERVER['HTTP_USER_AGENT']; echo " "; echo $_SERVER['SCRIPT_NAME']; ?> OUTPUT: /demo/demo_global_server.php 35.194.26.41 35.194.26.41 https://tryphp.w3schools.com/showphp.php?filename=demo_global_server Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:92.0) Gecko/20100101 Firefox/92.0 /demo/demo_global_server.php

$_GET •An associative array of variables passed to the current script via the HTTP GET method.

$_POST • An associative array of variables passed to the current script via the HTTP POST method.

$_REQUEST • An associative array consisting of the contents of $_GET, $_POST, and $_COOKIE. • <!DOCTYPE html> <html> <body> <form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>"> Name: <input type="text" name="fname"> <input type="submit"> </form> <?php if ($_SERVER["REQUEST_METHOD"] == "POST") { // collect value of input field $name = htmlspecialchars($_REQUEST['fname']); if (empty($name)) { echo "Name is empty"; } else { echo $name; } } ?> </body>

$_PHP_SELF • A string containing PHP script file name in which it is called. $_SERVER['PHP_SELF'] • The filename of the currently executing script, relative to the document root $_SERVER['SERVER_NAME'] • The name of the server host under which the current script is executing. If the script is running on a virtual host, this will be the value defined for that virtual host.

Working with Data and built-in functions of PHP

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