PHP - Wikitechy

What is the difference between session and cookies ?

webmaster — Thu, 04 Aug 2022 07:25:05 +0000

Session

Cookies

A temporary and interactive information interchange between two or more communicating devices or between a user and computer

Small pieces of data sent from a website and stored on the user’s computer by the user’s web browser while the user is browsing

Stored in the server side

Stored in the client’s browser as text files

It can store a large amount of data

It can store a minimum amount of data

It provides more security because it is difficult to access session values

It provides minimum security because it is easier to access cookie values

It holds multiple variables

It does not hold multiple variables

It is available until the browser is opened

It keeps the information until deleted by the user or set as per the timer

More reliable

Comparatively less reliable

Using session_destroy (), we will destroy sessions

Setting the cookie time to expire the cookie

Session depends on the cookie

Cookies does not depends on the cookie

What is Zend Engine and Zend Server in PHP ?

webmaster — Thu, 04 Aug 2022 07:12:37 +0000

As a compiler and runtime engine, Zend engine is used internally by PHP.
PHP Scripts are loaded into memory and compiled into Zend opcodes then the HTML generated is sent to the client and opcodes are executed.
It is an open-source scripting engine, commonly known it plays an important role in the web automation language PHP.
It provides resource and memory management and other standard services for the PHP language.
Its performance, extensibility, and reliability have played a significant role in PHP’s increasing popularity.
Zend Server is an official server of a local web application, then it enables us to deploy, debug, and prepare your production processes.
It handles clustering, hosting, file distribution, and file transfers when we install it on the server.
Along with updating existing code via an object-oriented interface, the code generator makes it possible to create new code.

What is the purpose of break and continue statement ?

webmaster — Thu, 04 Aug 2022 07:01:21 +0000

PHP also has two keywords break and continue to control the loop, just like another programming language.
Those statements are known as the flow of transfer or jumping statements in the program.

Break

The break statement is used inside the for loop, foreach loop, while loop and do-while loop and then switch case statement.
Inside a loop the break statement encountered then it immediately terminated the loop statement and transferred the control to the next statement, followed by a loop to resume the execution.
In nested loop statement it is also used, where it breaks the inner loop first and then proceed to break the outer loop.
In program it is also used in the switch case statement to terminate a particular case’s execution.
A break statement is placed inside the loop with a condition and then if the condition is true, a break statement is immediately executed to break the execution of the loop and to move the control to the next statement followed by the loop.

Sample Code


// defines the for loop   

for ($a = 0; $a < 10; $a++) {  

  if ($a == 7) {  

    break; /* Break the loop when condition is true. */  

  }  

  echo "Number: $a 
";  

}  

echo " Terminate the loop at $a number";  

?>

Output

Continue

It is used in the middle of for loop, while loop, do-while loop and for-each loop.
In a loop the continue statement is encountered then it skips the current iteration of the loop.
A continue statement is usually used with a condition inside a loop and then if the condition is true, the continue statement is executed to skip the iteration.
It transfers the control to the beginning of the loop for further execution inside the loop, after that.

Sample Code


// defines the for loop   

for ($a = 0; $a < 7; $a++) {  

  if ($a == 5) {  

  echo " Skipped number is $a 
"; // prints the skipped number.  

    continue; /* It skips the defined statement if the condition is true. */  

  

  }  

  echo "Number is: $a 
";  

}  

?>

Output

What is the use of count () function in PHP ?

webmaster — Thu, 04 Aug 2022 06:46:30 +0000

In PHP this unbuilt function is used to count the current elements in the array.
If it has been set to an empty array, whether the function might return 0 for the variable and the variable that is not set the function returns 0.
Generally, this function takes one parameter, the array for which the elements need to be counted.
The function an take a parameter mode which tells the function to count the element in recursive or normal mode but in addition.
In Count () syntax $array is mandatory and in which elements are needed to be counted.
In Count () mode is optional which is used to set the mode of function and their parameter can take two possible values, either 0 or 1. 1 generally indicates to count of the values of the array recursively.
In an array, the functions return the number of elements.

Syntax

Count ($array, mode)

Sample Code


  
   

            $cars=array("Volvo","Volkswagen","Hyundai","Ferrari");
       echo count($cars);
       ?>

Output

What is the difference between GET and POST Method ?

webmaster — Thu, 04 Aug 2022 06:33:30 +0000

GET	POST
In browser history parameters remain because they are the part of the URL	In browser history parameters remain because they are the part of the URL
It can be bookmarked	It cannot be bookmarked
If the HTML is stored in the browser cache, GET requests are re-executed but may not be re-submitted to server	The browser alerts the user that data will need to be re-submitted
It can send but the parameter data is limited to what we can stuff into the URL	It can send parameters, including uploading files to the server
Hacking becomes easier for script kiddies	Hacking becomes more difficult
There is restriction on form data type, only ASCII characters allowed	There is no restrictions. Binary data is also allowed
PHP GET method is less secure than POST because data sent is part of the URL. So, its saved in browser history or server logs in plaintext	PHP POST is little safer than GET because the parameters are not stored in browser history or web- server logs
There are restrictions on form data length	There are no restrictions on form data length
GET method should not be used while sending passwords or other sensitive information	POST method used when sending passwords or other sensitive information.
GET method is visible to everyone in address bar and it has limits on amount of information to send	POST method variables are not displayed in the URL
It can be cached	It cannot be cached

What does the unlink () function and unset () function mean ?

webmaster — Thu, 04 Aug 2022 05:46:18 +0000

The unlink () and unset () functions are used to do some undo operations but used in different situations because both acts differently.

unlink () function

In PHP unlink () function is used when you want to delete the files completely and it is an inbuilt function.
In this the filename of the file which has to be deleted is sent as a parameter and True on success and False on failure when the function returns.
The unlink () function accepts two parameters in PHP they are filename and context.
The filename is a mandatory parameter which specifies the filename of the file which has to be deleted.
The context is an optional parameter which specifies the context of the file handle which can be used to modify the nature of the stream.
Suppose there is a file named ‘gfg.txt’, it returns True on success and False on failure.

Sample Code

 
// PHP program to delete a file named gfg.txt
// using unlink() function
 
$file_pointer = fopen('gfg.txt');
 
// Writing on a file named gfg.txt
fwrite($file_pointer, 'A computer science portal for Wikitechy!');
fclose($file_pointer);
 
// Using unlink() function to delete a file
unlink('gfg.txt');
 
?>

Output

unset () function

The unset () function is used when you want to make that file empty and it is an inbuilt function which is used to remove the content from the file by emptying it in PHP.
Thereby making it empty, the unset () function not only clears the file content but also is used to unset a variable.
It means that the function clears the content of a file rather deleting it.
This function accepts single parameter variable which is required and it does not return any value.

Sample Code

      
$var = "hello";
         
// Change would be reflected outside the function 
function unset_value() {
    unset($GLOBALS['var']);
}
         
unset_value();
echo $var;
?>

Output

What is session in PHP ?

webmaster — Wed, 03 Aug 2022 12:37:58 +0000

PHP session is used to store and pass information from one page to another page temporarily until the user closes website.
In shopping website PHP website is widely used where we need to store and pass cart information from one page to another.
For example. username, product code, product name, product price etc.
The session creates unique user id for each browser to recognize the user and avoid conflict between multiple browsers.
PHP session_start () function is used to start the session and starts new and resume existing session.
If session is created already then it returns existing session and if session is not available, it returns and creates new session.
It is an associative array that contains all session variables and it is used to get and set session variables.

Syntax

  
           session_start();
  
            ?>

Sample Code

                 session_start();
                ?>
              
              
              

                             // Echo session variables that were set on previous page
                 echo "Favorite color is " . $_SESSION["favcolor"] . ".
";
                 echo "Favorite animal is " . $_SESSION["favanimal"] . ".";
              ?>

Output

What are the ways to define a constant in PHP ?

webmaster — Wed, 03 Aug 2022 12:03:36 +0000

PHP constants are identifier or name that can’t be changed during the execution of the script except for magic constants, which are not really constants.
Constants can never be undefined or changed, they are similar to the variable except once defined.
PHP constants follow the same PHP variable rules and it remains constant across the entire program.
Conventionally, in uppercase letters PHP constants should be defined and it can be started with an underscore or letter only.
PHP constants consists of two types, they are:
- Using define () function
- Using const keyword

Using define () function

In PHP use the define () function to create a constant and it defines constant at run time.
In this function name specifies the constant name, value specifies the constant value and case-insensitive specifies whether a constant is case-insensitive.
By default, if value is false it means it is case sensitive.

Sample Code

define("MESSAGE","Welcome to Wikitechy",true);//not case sensitive    
echo MESSAGE, "
";    
echo message;    
?>

Output

Using const Keyword

PHP introduces a const keyword to create a constant and it defines constants at compile time.
It constructs a language, not a function.
The constant defined using const keyword are case-sensitive.

Sample Code

    define("MSG", "Wikitechy");  
    echo MSG, "
";  
    echo constant("MSG");  
    //both are similar  
?>

Output

What is echo and print in PHP ?

webmaster — Tue, 02 Aug 2022 12:35:01 +0000

PHP is not a function; it is a language construct and its output become one or more string.
If you want to pass more than one parameter to echo, the use of parentheses is required.
PHP echo statement is used to print the string, array, variable multi-line strings, escaping characters, etc.
Echo is used to display the output, because it is a statement and does not return any value.
Echo can be used with echo () or without parentheses echo.
In echo, we can pass multiple strings separated by a comma (,).
The PHP print can be used alternative to echo many times and its statement is similar to the echo statement.
In PHP print accepts one argument at a time & cannot be used as a variable function.
Echo is faster than the print statement and print outputs only the strings.
The main difference between the echo and print statement is that echo does not behave like function whereas print behave like a function.

Sample Code : Echo Statement





echo "PHP is Fun!
";
echo "Welcome to wikitechy!
";
echo "I'm about to learn PHP!
";
echo "This ", "string ", "was ", "made ", "with multiple parameters.";
?>

Output

Sample Code: Print Statement





$txt1 = "Learn PHP";
$txt2 = "Wikitechy.com";
$x = 5;
$y = 5;

print "" . $txt1 . "
";
print "Study PHP at " . $txt2 . "
";
print $x + $y;
?>

Output

What is NULL in PHP ?

webmaster — Tue, 02 Aug 2022 12:16:39 +0000

In PHP null () function is an inbuilt function which is used to find whether a variable is NULL or not.
If it returns True the given variable is null, otherwise it returns False.
If the value of $x is equal to NULL it returns true and it is an identical comparison operator.
In PHP null is a special data type which can have only one value that is NULL.
NULL data type is a variable that has no value assigned to it and then any variable can be empty by setting the value NULL to the variable.

Sample Code





$apple = 0;
echo "apple is " . is_null($a) . "
";

$orange = null;
echo "orange is " . is_null($b) . "
";

$grape = "null";
echo "grape is " . is_null($c) . "
";

$watermelon = NULL;
echo "watermelon is " . is_null($d) . "
";
?>

Output

What are the types of errors in PHP ?

webmaster — Tue, 02 Aug 2022 10:54:21 +0000

In a programmer, error is a mistake that may be caused by writing incorrect code or incorrect syntax.
An error message is displayed on your browser containing the filename along with a message describing the error, location and the line number in which error has occurred.
In PHP there are various types of errors that contains basically four main types of errors, they are
- Syntax Error or Parse Error
- Fatal Error
- Warning Error
- Notice Error

Syntax Error or Parse Error

A syntax error is a mistake in the syntax of source code, which can be done by programmers due to their lack of knowledge or concern.
At compile time compiler is used to catch the syntax error.
Due to common reasons these errors can occur like missing semicolon, unclosed quotes, or unclosed brackets, extra or missing parentheses and many more.
While compiling the program syntax error can be caught by the compiler and gives a syntax error or parse error message.

Sample Code

    /*------------------syntax error-------------------*/  
    echo "Venkat: Hie! I'm Venkat. 
";  
    echo "Lokesh: I'm Lokesh. How are you?"  
    echo "Venkat: I'm good! and you?";  
    echo "Lokesh: I'm also good";  
?>

Output

Fatal Error

Fatal error is another type of error, which is occurred due to the use of undefined function.
The PHP compiler understands the PHP code and also recognizes the undefined function.
PHP compiler generates a fatal error, when a function is called without providing its definition.

Sample Code

    /*------------------fatal error-------------------*/  
    function add($f1, $f2) {  
        $sum = $f1 + $f2;  
        echo "Addition:" . $sum;  
    }  
      
    $f1 = 23;  
    $f2 = 56;  
      
    //call the function that is not defined  
    //Generate fatal error  
    catch_fatal_error();  
    //echo "Fatal Error";     
?>

Output

Warning Error

When the programmer tries to include a missing file there warning error is generated.
The PHP function calls that missing file which does not exist and warning error does not stop/prevent the execution of the program.

Sample Code

    /*-------------------warning error------------------*/  
    $cmpny = 'Wikitechy';  
    echo "Warning Error: ";  
      
    //include a file in the code  
    include ('jtp.php');      
?>

Output

Notice Error

Notice error is also same as warning error, when program contains something wrong, the notice error occurs.
Including a notice error, it allows/continue the execution of the program.
Notice error does not prevent the execution of the code and generally it occurs when we try to use or access a variable which is undefined.

Sample Code

    /*------------------notice error-------------------*/  
    $telecom = "Airtel";  
    echo $telecom;  
    echo $automobile;  
?>

Output

What are the types of arrays in PHP ?

webmaster — Tue, 02 Aug 2022 08:57:09 +0000

In PHP an array is a type of data structure that allows us to store multiple elements of similar data type under a single variable thereby saving us the effort of creating a different variable for every data.
Using their index or key arrays are helpful to create a list of elements of similar types, which can be accessed.
Suppose accordingly we want to store five names and print them and it can be easily done by the use of five different string variables.
Instead of five string variables, the number rises to a hundred, then it would be really difficult for the developer or user to create so many different variables.
Also using an index or a key array comes into play and helps us to store every element within a single variable and also allows easy access.
In PHP an array is created using array() function and basically there three types, they are

1. Indexed array
2. Associative array
3. Multidimensional array

Indexed array

Indexed array is represented by number which starts from 0 and we can store integer, object and string in the PHP array.
By default, all PHP array elements are assigned to an index number.

Sample Code

$season=array("January","February","March","April");  
echo "Month are: $month[0], $month[1], $month[2] and $month[3]";  
?>

Output

Associative Array

Associative arrays are similar to the indexed arrays but instead of linear storage, every value can be assigned with a user-defined key of string type.
In PHP we can associate name with each array elements by using => symbol.

Sample Code

$salary["Venkat"]="350000";    
$salary["Kishore"]="450000";    
$salary["Nizar"]="200000";    
echo "Venkat salary: ".$salary["Venkat"]."
";  
echo "Kishore salary: ".$salary["Kishore"]."
";  
echo "Nizar salary: ".$salary["Nizar"]."
";  
?>

Output

Multidimensional Array

PHP multidimensional array is otherwise known as array of arrays and allows you to store tabular data in an array.
In the form of matrix PHP multidimensional array can be represented which is represented by row * column.

Sample Code

$emp = array  
  (  
  array(1,"Venkat",400000),  
  array(2,"Kishore",500000),  
  array(3,"Nizar",300000)  
  );

Output

Name

Salary

Venkat

400000

Kishore

500000

Nizar

300000

What are the methods to submit form in PHP ?

webmaster — Tue, 02 Aug 2022 07:24:43 +0000

In PHP we can create and use forms in which we need to use PHP superglobals $_GET and $_POST to get form data.
If the form request get or post we need to use $_GET, for post request $_POST to retrieve data from get request.
In this get request is the default form request in which the data is passed through get request is visible on the URL browser so it is not secured and we can send limited amount of data through get request.
Post request is widely used to submit form that have large amount of data such as image upload, file upload, registration form, login form, etc.
In this the data passed through post request is not visible on the URL browser so it is secured and we can send large amount of data through post request.

Sample Code





Name: 

E-mail:

Output

What are Magic Constants in PHP ?

webmaster — Mon, 01 Aug 2022 09:09:07 +0000

In PHP magic constants are the predefined constants which is used on the basis of their use.
Constants are created by various extensions and there are nine magic constants in the PHP and all of the constant resolved at the compile-time, not like the regular constant which is resolved at run time.
In this there are eight magic constants which start and end with double underscores (__), they are.
- __line__
- __file__
- __dir__
- __function__
- __class__
- __method__
- __namespace__
- __trait__

line

This type of magic constant returns the current line number of the file.
In our program file if we use this magic constant somewhere then this constant will display the line number during compile time.

Syntax

         __line__

file

This type of magic constant return the full path of the executed file with the name of the file.

Syntax

         __file__

dir

This type of magic constant returns the directory of the executed file.

Syntax

          __dir__

function

This type of magic constant returns the name of the function where it is included.

Syntax

         __function__

class

This type of magic constant returns the name of the class where it is included.

Syntax

__class__

method

This type of magic constant returns the method name where it is included.

Syntax

       __method__

namespace

This type of magic constant returns the current namespace where it is included.

Syntax

       __namespace__

trait

This type of magic constant returns the trait name where it is included.

Syntax

  __trait__

What are the different loops in PHP ?

webmaster — Mon, 01 Aug 2022 08:43:27 +0000

Like any other language, in PHP loop is used to execute a statement or a block of statements, multiple times until and unless a specific condition is met.
Loops helps the user to save both effort and time of writing the same code multiple times.
PHP supports four types of looping techniques, they are:

1. For loop
2. While loop
3. Do-while loop
4. Foreach loop

For loop

For loop is used when the user knows in advance, how many times the block needs to execute.
The number of iterations is known beforehand and these types of loops are also known as entry-controlled loops.
Initialization expression, test expression, update expression are the three main parameters to the code.

Syntax

for (initialization expression; test condition; update expression) {
          // code to be executed
        }

While loop

While loop is also an entry control loop like for loop condition.
First it checks the condition at the start of the loop and if its true then it enters the loop and executes the block of statements, and goes on executing it as long as the condition holds true.

Syntax

             while (if the condition is true) {
              // code is executed
         }

Do-while loop

Do while loop is an exit control loop which means that it first enters the loop, executes the statements, and then checks the condition.
Using do-while a statement is executed at least once.
The program is executed as long as the condition holds true, after executing once.

Syntax

do {

               //code is executed

         } while (if condition is true);

Foreach loop

Foreach loop is used to iterate over arrays and for every counter of loop, an array element is assigned and the next counter is shifted to the next element.

Syntax

foreach (array_element as value) {
         //code to be executed
       }

What are cookies ? How to create cookies in PHP ?

webmaster — Mon, 01 Aug 2022 06:11:36 +0000

In PHP cookie is a small file with a maximum size of 4KB that the web server stores on the client computer.
Cookies are typically used to keep track of information such as a username that the site can retrieve to personalize the page when the user visits the website next time.
They can only be read from the domain that it has been issued from.
In browser cookies are usually set in an HTTP header but JavaScript can also set a cookie directly.
In PHP setcookie () function is used to set a cookie.
This function needs to be called prior to any output generated by the script otherwise the cookie will not be set.
In setcookie () function name parameter is used to set the name of the cookie and value parameter is used to set the value of the cookie.
In setcookie () function expire parameter is used to set the expiry timestamp of the cookie after which the cookie can’t be accessed.
In setcookie () function path parameter is used to specify the path on the server for which the cookie will be available.
In setcookie () function domain parameter is used to specify the domain for which the cookie is available.
In setcookie () function security parameter is used to indicate that the cookie should be sent only if a secure HTTPS connection exists.

Syntax

setcookie (name, value, expire, path, domain, security);

Sample Code


setcookie("test_cookie", "test", time() + 3600, '/');
?>



if(count($_COOKIE) > 0) {
    echo "Cookies are enabled.";
} else {
    echo "Cookies are disabled.";
}
?>

Output

List out the features of PHP

webmaster — Mon, 01 Aug 2022 06:00:05 +0000

Performance

Compare to other languages such as JSP and ASP, PHP script is executed much faster than those scripts which are written.
The server workload and loading time is automatically reduced, which results in faster processing better and speed performance, while PHP uses its own memory.

Open Source

In the web PHP source code and software are freely available.
Without paying any cost, we can develop all the versions of PHP according to our requirement.

Familiarity with syntax

PHP programmers are comfortable coding with it and it has easily understandable syntax.

Embedded

Within HTML tags and script tags, PHP code can be easily embedded.

Platform Independent

PHP application developed in one OS it can be easily executed in other OS also and it is available for Mac, Windows, Linux and Unix.

Database Support

PHP supports all the leading databases such as MySQL, Oracle Database Corporation, SQLite, etc.

Error Reporting

At runtime PHP has predefined error reporting constants to generate an error notice or warning.

Loosely Typed Language

PHP allows us to use a variable without declaring its datatype and automatically it will be taken at the time of execution based on the type of data it contains on its value.

Web servers Support

Local servers like Apache, Netscape, Microsoft IIS, etc. are compatible with PHP.

Security

To develop the website PHP is a secure language and it consists ofmultiple layers of security to prevent threads and malicious attacks.

Control

In a few lines of code different programming languages require long script or code, whereas PHP can do the same work.

A Helpful PHP Community

Learning PHP from the communities is one of the significant benefits and it has a large community of developers who regularly updates tutorials, online help, FAQs and documentation.

How to read a file in PHP ?

webmaster — Mon, 01 Aug 2022 05:45:29 +0000

PHP File provides various functions to read data.
There are different functions that allow you to read all file data, read data character by character and read data line by line.
The PHP file available read functions are given below, they are:

1. fread ()
2. fgets ()
3. fgetc ()

PHP Read File- fread ()

PHP fread () function is used to read data of the file and it consists of two arguments, they are file size and file resource.

Sample Code

$filename = "c:\\file1.txt";    
$fp = fopen($filename, "r");//open file in read mode    
  
$contents = fread($fp, filesize($filename));//read file    
  
echo "$contents
";//printing data of file  
fclose($fp);//close file    
?>

Output

PHP Read file- fgets ()

To read single line from the file PHP fgets () function is used.

Sample Code

$fp = fopen("c:\\file1.txt", "r");//open file in read mode    
echo fgets($fp);  
fclose($fp);  
?>

Output

PHP Read file- fgetc ()

To read single character from the file PHP fgetc () function is used and use! feof () function inside the while loop to get all data using fgetc () function.

Sample Code

$fp = fopen("c:\\file1.txt", "r");//open file in read mode    
while(!feof($fp)) {  
  echo fgetc($fp);  
}  
fclose($fp);  
?>

Output

How many data types are there in PHP ?

webmaster — Sat, 30 Jul 2022 10:49:13 +0000

PHP data types are used to hold different types of values or data.
There are eight primitive data types which are further categorized into three types, they are:
- Scalar types
- Compound types
- Special types

Scalar data types

Scalar data types hold only single value and it consists of four data types, they are boolean, integer, float and string.

Boolean

Booleans are the simplest data type works like switch and holds only two values TRUE (1) or FALSE (0).
It is often used with conditional statements were if the condition is correct, it returns TRUE otherwise FALSE.

Sample Code

    if (TRUE)  
        echo "This condition is TRUE.";  
    if (FALSE)  
        echo "This condition is FALSE.";  
?>

Output

Integer

Integer means numeric data, it can be either positive or negative sign.
It holds only whole numbers, like numbers without decimal points or fractional parts.

Sample Code

    $dec1 = 34;  
    $oct1 = 0243;  
    $hexa1 = 0x45;  
    echo "Decimal number: " .$dec1. "
";  
    echo "Octal number: " .$oct1. "
";  
    echo "HexaDecimal number: " .$hexa1. "
";  
?>

Output

Float

A floating-point number is a number with a decimal point and unlike integer, it can hold numbers with a fractional or decimal point, including a negative or positive sign.

Sample Code

    $n1 = 19.34;  
    $n2 = 54.472;  
    $sum = $n1 + $n2;  
    echo "Addition of floating numbers: " .$sum;  
?>

Output

String

String is a non-numeric data type which holds letters or any alphabets, numbers, and even special characters.
Its value must be enclosed either within single quotes or in double quotes and both are treated differently.

Sample Code

    $company = "Wikitechy";  
    //both single and double quote statements will treat different  
    echo "Welcome to $company";  
    echo "
";  
    echo "Welcome to $company';  
?>

Output

Compound data type

Compound data type can hold multiple and it consists of two data types, they are array and object.

Array

In single variable an array canstore multiple values of same data type.

Sample Code


    $bikes = array ("Royal Enfield", "Yamaha", "KTM");  

    var_dump($bikes);   //the var_dump() function returns the datatype and values 

    echo "
";  

    echo "Array Element1: $bikes[0] 
";  

    echo "Array Element2: $bikes[1] 
";  

    echo "Array Element3: $bikes[2] 
";  

?>

Output

Object

Objects are the instances of user-defined classes that can store both functions and values.
It must be explicitly declared.

Sample Code

     class bike {  
          function model() {  
               $model_name = "Jawa";  
               echo "Bike Model: " .$model_name;  
             }  
     }  
     $obj = new bike();  
     $obj -> model();  
?>

Output

Special Data Type

Special data types consist of two types, they are Null and resource data type.

Null

Null is a special data type that has only one value is NULL and there is a convention of writing it in capital letters as it is case sensitive.
In special data type NULL defined a variable with no value.

Sample Code

     $nl = NULL;  
    echo $nl;   //it will not give any output  
    ?>

Output

Resource:

In PHP resources are not the exact data type and basically these are used to references to external PHP resources or store some small function calls.

How to create a database using PHP and MySQL ?

webmaster — Thu, 28 Jul 2022 05:18:54 +0000

Database is a collection of inter-related data which helps in insertion, retrieval and deletion of data from database and organizes the data in the form of views, tables, reports, schemas etc.
For example, institute database organizes the data about students, admin, faculty, and staff etc. which helps in insertion, efficient retrieval and deletion of data from it.
In MySQL we need to create a database to execute a query.
MySQL is an open-source relational database management system and it is distributed, supported and developed by Oracle Corporation.
MySQL is a database system that runs on a server and it is ideal for both small and large applications.
From PHP script establish a connection to MySQL server.
Write a SQL query to create a database and store it in a string variable then execute the queries.
Using Object-oriented procedure, we can use the query () function of MySQLi class to execute our query.
Using procedural procedure, we can use the mysqli_query () function of PHP to execute our query.
Using PDO procedure then we can execute our query.

Sample Code

$servername = "localhost";
$username = "username";
$password = "password";

// Creating a connection
$conn = new mysqli($servername, $username, $password);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
} 
// Creating a database named newDB
$sql = "CREATE DATABASE newDB";
if ($conn->query($sql) === TRUE) {
    echo "Database created successfully with the name newDB";
} else {
    echo "Error creating database: " . $conn->error;
}

// closing connection
$conn->close();
?>