PHP Tutorials for Freshers & Experienced

Friday, November 30, 2018

How To Setup Cron Job on AWS

By 11/30/2018 No comments:

Cron job is a process to run a page automatically in background without interrupting user. You can execute a page automatically at any time on daily basis by setting up a cron job.

I have already explained about setting up a cron job on godaddy server in one of my article. So now here I am going to explain a step by step process for setting up cron job in AWS too for ubuntu users.

Process to Setting Up AWS Cron:-

Step #1. Login to your AWS instance through Terminal by using your server credentials.

Step #2. Type crontab -e.

Step #3. Now editor will open inside your terminal that will look like below..

Step #4. You have to add your script command inside it as below.

* * * * * php /var/www/html/myscript.php

Here 5 star shows -

1st * is for minute (0-59)

2nd * is for hour (0-23)

3rd * is for day (1-31)

4th * is for month (1-12)

5th * is for day-of-week (0-7[where both 0 and 7 mean Sun, 1 = Mon, 2 = Tue, etc])

After setting cron time in min, hour, day, month, day-of-week we set our file path which we want to execute automatically according to date & time.

You can edit cron by pressing Insert key from keyboard and to paste your command inside editor you have to press ctrl+shift+v.

Now press esc and after that type :wq to save and exit from editor.

Step #5. Now check your cron is save successfully or not by typing crontab -l in terminal.

Step #6. Make sure you change your file permission executing command chmod 755 /var/www/html/myscript.php in terminal.

myscript.php


<?php

$to = "[email protected]"; 

$fr_email = '[email protected]'; 

$subj = 'Hi this is from AWS Cron';

/* Create a simple msg body */

$body = "Welcome to myscript\n";

$body .= "\n";

// Now send email

mail($to,  $subj, $body, "From: <$fr_email>");

?>

You will get an email every time when your cron will run as per your above php script.

More About Cron Job:

Process to set up cron job in GoDaddy server (scheduled task)

Top PHP7 Interview Questions And Answers for Freshers & Experienced

By 10/27/2018 No comments:

This article shows up top frequently asked PHP7 interview questions and answers for PHP Developers, This list of PHP interview questions and answers will be helpful for PHP programmers.

Top PHP7 Interview Questions And Answers for Freshers & Experienced

Question #1 - How array_walk function works in PHP?

It is used to update the elements/index of original array.

How: in array_walk, two parameter are required.

original array
An callback function, with use of we update the array.

Question #2 - How to achieve Multilevel inheritance in PHP7?

//base class
class a{}

//parent class extend the base class
class bextends a{}

//chid class extend the parent class
class c extends b{}

Question #3 - How to get 2nd highest salary of employee, if two employee may have same salary?

select salary from employee group by salary order by salary limit 1,1

Question #4 - require_once(), require(), include().What is difference between them?

require() includes and evaluates a specific file, while require_once() does that only if it has not been included before (on the same page). So, require_once() is recommended to use when you want to include a file where you have a lot of functions for example. This way you make sure you don't include the file more times and you will not get the "function re-declared" error.

Question #5 - What type of inheritance supports by PHP7?

There are following type of inheritance

Single Inheritance - Support by PHP
Multiple Inheritance - Not support
Hierarchical Inheritance - Support by PHP
Multilevel Inheritance - Support by PHP

Question #6 - How do you call a constructor for a parent class?

parent::constructor($value);

Question #7 - How to find duplicate email records in users table?

SELECT u1.first_name, u1.last_name, u1.email FROM users as u1
INNER JOIN (
    SELECT email FROM users GROUP BY email HAVING count(id) > 1
    ) u2 ON u1.email = u2.email;

Question #8- What is the difference between Session and Cookie?

Both are used to store user information on server. The main difference between sessions and cookies is that sessions are stored on the server, and cookies are stored on the user's computers in the text file format. Cookies can't hold multiple variable while session can hold multiple variables..We can set expiry for a cookie,The session only remains active as long as the browser is open.Users do not have access to the data you stored in Session,Since it is stored in the server.Session is mainly used for login/logout purpose while cookies using for user activity tracking

Question #9- How to pass data in header while using CURL?

$url='http://www.web-technology-experts-notes.in';
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 0);
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
  'headerKey: HeaderValue ',
  'Content-Type: application/json',
  "HTTP_X_FORWARDED_FOR: xxx.xxx.x.xx"
));
echo curl_exec($ch);
curl_close($ch);

Question #10 - What is Final Keyword in PHP7?

PHP7 introduces the final keyword, which prevents child classes from overriding a method by prefixing the definition with final keyword.

Question #11 - How can we prevent SQL-injection in PHP?

Sanitize the user data before Storing in database.

While displaying the data in browser Convert all applicable characters to HTML entities using htmlentities functions.

Question #12 - How to set header in CURL?

curl_setopt($ch, CURLOPT_HTTPHEADER, Array("Content-Type: text/xml"));

Question #13 - What are different type of sorting functions in PHP7?

sort() - sort arrays in ascending order.
asort() - sort associative arrays in ascending order, according to the value.
ksort() - sort associative arrays in ascending order, according to the key.
arsort() - sort associative arrays in descending order, according to the value.
rsort() - sort arrays in descending order.
krsort() - sort associative arrays in descending order, according to the key.
array_multisort() - sort the multi dimension array.
usort()- Sort the array using user defined function.

Question #14 - How to redirect https to http URL and vice versa in .htaccess?

Redirect https to http

RewriteEngine On
RewriteCond %{HTTPS} on
RewriteRule (.*) http://%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

Redirect http to https

RewriteEngine on
RewriteCond %{HTTPS} off
RewriteRule ^(.*)$ https://%{HTTP_HOST}/$1 [R=301,L]

Question #15 - What are benefits of .htaccess?

Routing the URL
Mange Error Pages for Better SEO
Redirection pages
Detect OS (like Mobile/Laptop/Ios/Android etc)
Set PHP Config variable
Set Environment variable
Allow/Deny visitors by IP Address
Password protection for File/Directory
Optimize Performance of website
Improve Site Security

Question #16 - How we can retrieve the data in the result set of MySQL using PHP7?

mysqli_fetch_row()
mysqli_fetch_array()
mysqli_fetch_object()
mysqli_fetch_assoc()

Question #17 - What is the use of explode() function ?

This function is used to split a string into an array. Syntax : array explode( string $delimiter , string $string [, int $limit ] );

Question #18 - What is the difference between explode() and split() functions?

Split function splits string into array by regular expression. Explode splits a string into array by string.

Both function are used to breaks a string into an array, the difference is that Split() function breaks split string into an array by regular expression and explode() splits a string into an array by string. explode() is faster than split() because it does not match the string based on regular expression.

Question #19 - What is the use of mysqli_real_escape_string() function?

mysqli_real_escape_string() function mainly used to escapes special characters in a string for use in an SQL statement

Question #20 - Write down the code for save an uploaded file in php.

if ($_FILES["file"]["error"] == 0)
{
move_uploaded_file($_FILES["file"]["tmp_name"],
"upload/" . $_FILES["file"]["name"]);
echo "Stored in: " . "upload/" . $_FILES["file"]["name"];
}

Question #21 - How to create a text file in php7?

$filename = "/home/user/guest/newfile.txt";
$file = fopen( $filename, "w" );
if( $file == false )
{
echo ( "Error in opening new file" ); exit();
}
fwrite( $file, "This is a simple test\n" );
fclose( $file );

Question #22 - How to strip whitespace (or other characters) from the beginning and end of a string ?

We can use trim() function to remove whitespaces or other predefined characters from both sides of a string.

Question #23 - What is output of following?

$a = '10';
$b = &$a;

$b = "2$b";

echo $a;
echo $b;

Output

210
210

Question #24 - What are Traits?

Traits are a mechanism that allows you to create reusable code in PHP7 where multiple inheritance is not supported. To create a Traits we use keyword trait.

Example of Traits

trait users {
    function getUserType() { }
    function getUserDescription() {  }
    function getUserDelete() {  }
}

class ezcReflectionMethod extends ReflectionMethod {
    use users;    
}

class ezcReflectionFunction extends ReflectionFunction {
    use users;
}

Question #25 - How to extend a class defined with Final?

No, You can't extend. A class declare with final keyword can't be extend.

Question #26 - What is full form of PSRs?

PHP Standards Recommendations.

Question #27 - How do you execute a PHP script from the command line?

Get the php.exe path from server (My PHP path is : D:\wamp\bin\php\php5.5.12)
In environment variable, Add this path path under PATH variable.
Re-start the computer.
Now, you can execute php files from command file.

php index.php

Question #28 - What is stdClass in PHP7?

It is PHP7 generic empty class.
stdClass is used to create the new Object. For Example

$newObj = new stdClass();
$newObj->name='What is your name?';
$newObj->description='Tell me about yourself?';
$newObj->areYouInIndia=1;
print_r($newObj);

Output

stdClass Object
(
    [name] => What is your name?
    [description] => Tell me about yourself?
    [areYouInIndia] => 1
)

Question #29 - How to start displaying errors in PHP7 application ?

Add following code in PHP.

ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);

OR
Add following code in .htacess

php_flag display_startup_errors on
php_flag display_errors on
php_flag html_errors on
php_flag  log_errors on

Question #30 - What are different type of errors?

E_ERROR: A fatal error that causes script termination.
E_WARNING: Run-time warning that does not cause script termination.
E_PARSE: Compile time parse error.
E_NOTICE: Run time notice caused due to error in code.
E_CORE_ERROR: Fatal errors that occur during PHP's initial startup.
E_CORE_WARNING: Warnings that occur during PHP's initial startup.
E_COMPILE_ERROR: Fatal compile-time errors indication problem with script.
E_USER_ERROR: User-generated error message.
E_USER_WARNING: User-generated warning message.
E_USER_NOTICE: User-generated notice message.
E_STRICT: Run-time notices.
E_RECOVERABLE_ERROR: Catchable fatal error indicating a dangerous error
E_ALL: Catches all errors and warnings

Question #31 - When to use self over $this?

Use $this to refer to the current object.

Use self to refer to the current class.

Example of use of $this

class MyClass1 {
    private $nonStaticMember = 'nonStaticMember  member Called.';        
    
    public function funcName() {
        return $this->nonStaticMember;
    }
}

$classObj = new MyClass1();
echo $classObj->funcName();//nonStaticMember  member Called.

Example of use of SELF

class MyClass2 {
    private static $staticMember = 'staticMember  member Called.';        
    
    public function funcName() {
        return self::$staticMember;
    }
}

$classObj = new MyClass2();
echo $classObj->funcName(); //staticMember  member Called.

PHP Program To Find Odd Even Number

By 8/08/2018 No comments:

"Find odd even number " is the basic PHP program for a PHP learner. As you all aware, Odd numbers are not divisible by 2 and Even numbers are divisible by 2.

Example :

Odd number: 3, 5, 7, 9,11

Even number: 2, 4, 6, 8, 10

So here I am gonna explain it with a simple PHP program.

Odd Even Number Program :-

<?php

$number=22;

if($number%2==0)
{
 echo "22 is an even number"; 
}
else
{
 echo "22 is not odd number";
} 

?>

Output :-

22 is an even number

You can also do this by defining a PHP function to check a number is odd or even as below -

PHP function to check odd even number :-

<?php
function checkOddEven($num)
{
   if($num%2==0)
   {
     $result = "Even number"; 
   }
   else
   {
     $result = "Odd number";
   }
   retrun $result;
}

echo checkOddEven(43);
?>

Output :-

Odd number

Swap Two Number Program In PHP

By 8/07/2018 No comments:

Swap Two Numbers Program || PhpMyPassion

Swap two number generally is the process of interchange two variables with each other. Just suppose you have X whose value 10 there is another number Y with value of 20. Now if we swap these two number with each other then the X value will change to 20 and Y value will change to 10.

So here I am gonna explain with a simple PHP program.

Swap Two Number Program :-

<?php

$x=10;
$y=20;

echo "Value of x: $x</br>";
echo "Value of y: $y</br>";

$temp=$x;
$x=$y;
$y=$temp;

echo "Value of x: $x</br>";
echo "Value of y: $y</br>";

?>

Output :-

Value of x: 10
Value of y: 20
Value of x: 20
Value of y: 10

You can also do this by without using third variable as below -

Swap Two Number Without Using Third Variable Program :-

<?php

$x=10;
$y=20;

echo "Value of x: $x</br>";
echo "Value of y: $y</br>";

$x=$x+$y;
$y=$x-$y;
$x=$x-$y;

echo "Value of x: $x</br>";
echo "Value of y: $y</br>";

?>

Output :-

Value of x: 10
Value of y: 20
Value of x: 20
Value of y: 10

Armstrong Number Program in PHP

By 8/06/2018 No comments:

"Armstrong Number Program" is the initial program from where most of the beginner developers will start to learn and write code in any language. An Armstrong number is a number that is the sum of its own digits each raised to the power of the number of digits is equal to the number itself.

Here is an example of check a armstrong number in PHP.

Armstrong Number Program :-

Below is the simple PHP program to check a number armstrong.

<?php

$number=153;
$sum=0;
$temp=$number;
while($temp!=0)
{
$reminder=$temp%10;
$sum=$sum+$reminder*$reminder*$reminder;
$temp=$temp/10;
}
if($number==$sum)
{
echo "It is an Armstrong number";
}
else
{
echo "It is not an armstrong number";
}

?>

Output :-

It is an Armstrong number

Process to Install Docker on Ubuntu 16.04

By 8/04/2018 No comments:

Docker :-

Docker is a container management service. The keywords of Docker are develop, ship and run anywhere. The whole idea of Docker is for developers to easily develop applications, ship them into containers which can then be deployed at anyplace.

Docker has two flavors :

Community Edition (CE)
Enterprise Edition (EE)

So if you don't know which one should be install, just pick up The Community Edition (CE) flavor and install as below

Docker Installation :-

Follow the step by step process -

Step#1 :- Set up the docker repository

$ sudo apt-get update
$ sudo apt-get install apt-transport-https ca-certificates curl software-properties-common
$ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
$ sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"

Step#2 :- Install Docker CE

$ sudo apt-get update
$ sudo apt-get install docker-ce

Step#3 :- Verify the installation

$ sudo docker run hello-denny

So above process will help you to install

Docker on Linux environment. If you found any difficultly, do follow the Ubuntu installation instruction list all you need in detail.

Friday, November 30, 2018

How To Setup Cron Job on AWS

More About Cron Job:

Saturday, October 27, 2018

Top PHP7 Interview Questions And Answers for Freshers & Experienced

Wednesday, August 8, 2018

PHP Program To Find Odd Even Number

Odd Even Number Program :-

Output :-

PHP function to check odd even number :-

Output :-

Tuesday, August 7, 2018

Swap Two Number Program In PHP

Swap Two Number Program :-

Output :-

Swap Two Number Without Using Third Variable Program :-

Output :-

Monday, August 6, 2018

Armstrong Number Program in PHP

Armstrong Number Program :-

Output :-

Saturday, August 4, 2018

Process to Install Docker on Ubuntu 16.04

Docker :-

Docker has two flavors :

Docker Installation :-

Know More About Docker:

What is docker and uses ?

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