October 31, 2018

Sreekanth B

Asus Most Frequently Asked Latest PHP Interview Questions Answers

How to run the interactive PHP shell from the command line interface?

Just use the PHP CLI program with the option -a as follows:

php -a

Is multiple inheritance supported in PHP?

PHP supports only single inheritance; it means that a class can be extended from only one single class using the keyword 'extended'.

What is the meaning of a final class and a final method?

'final' is introduced in PHP5. Final class means that this class cannot be extended and a final method cannot be overridden.

How is the comparison of objects done in PHP?

We use the operator '==' to test is two objects are instanced from the same class and have same attributes and equal values. We can test if two objects are referring to the same instance of the same class by the use of the identity operator '==='.

What do the initials of PHP stand for?

PHP means PHP: Hypertext Preprocessor.

Which programming language does PHP resemble?

PHP syntax resembles Perl and C

What does PEAR stand for?

PEAR means "PHP Extension and Application Repository". It extends PHP and provides a higher level of programming for web developers.

What is the actually used PHP version?

Version 7.1 or 7.2 is the recommended version of PHP.

What Happens If An Expected Input Field Was Not Submitted?

Obviously, if an expected input field was not submitted, there will no entry in the $_REQUEST array for that field. You may get an execution error, if you are not checking the existence of the expected entries in $_REQUEST. For example, if you copy processing_forms.php to your local Web server, and run your browser with http://localhost/processing_forms.php?name=Joe, you will an error page like this:
You have submitted the following information:
Name = Joe
Comments =
Thank you!
PHP Notice: Undefined index:
comment in ...\processing_forms.php on line 3
Asus Most Frequently Asked Latest PHP Interview Questions Answers
Asus Most Frequently Asked Latest PHP Interview Questions Answers

How To Avoid The Undefined Index Error?

If you don't want your PHP page to give out errors as shown in the previous exercise, you should consider checking all expected input fields in $_REQUEST with the isset() function as shown in the example script below:
<?php
if (isset($_REQUEST['name'])) {
$name = $_REQUEST['name'];
} else {
$name = "";
}
if (isset($_REQUEST['comment'])) {
$comment = $_REQUEST['comment'];
} else {
$comment = "";
}
print("<html><pre>");
print("You have submitted the following information:\n");
print(" Name = $name\n");
print(" Comments = $comment\n");
print("Thank you!\n");
print("</pre></html>\n");
?>

How To List All Values Of Submitted Fields?

If you want list all values of submitted fields, you can write a simple loop to retrieve all entries in the $_REQUEST array. Below is an improved version of processing_forms.php to list all submited input values:
<?php
print("<html><pre>");
$count = count($_REQUEST);
print("Number of values: $count\n");
foreach ($_REQUEST as $key=>$value) {
print(" $key = $value\n");
}
print("</pre></html>\n");
?>

How To Retrieve The Original Query String?

If you have coded some values in the URL without using the standard form GET format, you need to retrieve those values in the original query string in $_SERVER['QUERY_STRING']. The script below is an enhanced version of processing_forms.php which print the original query string:
<?php
print("<html><pre>");
print(" query_string = {$_SERVER['QUERY_STRING']}\n");
$count = count($_REQUEST);
print("Number of values: $count\n");
foreach ($_REQUEST as $key=>$value) {
if (is_array($value)) {
print(" $key is an array\n");
for ($i = 0; $i < count($value); $i++) {
$sub_value = $value[$i];
if (get_magic_quotes_gpc()) {
$sub_value = stripslashes($sub_value);
}
print(" ".$key."[".$i."] = ".$sub_value."\n");
}
} else {
if (get_magic_quotes_gpc()) {
$value = stripslashes($value);
}
print(" $key = $value\n");
}
}
print("</pre></html>\n");
?>

How To Support Multiple-page Forms?

If you have a long form with a lots of fields, you may want to divide the fields into multiple groups and present multiple pages with one group of fields on one page. This makes the a long form more user-friendly. However, this requires you to write good scripts that:
• When processing the first page and other middle pages, you must keep those input values collected so far in the session or as hidden values in the next page form.
• When processing the last page, you should collect all input values from all pages for final process, like saving everything to the database.

How To Close A Session Properly?

Let's say you site requires users to login. When a logged in user clicks the logout button, you need to close the session associated with this user properly in 3 steps:

1. Remove all session values with $_SESSION = array().
2. Remove the session ID cookie with the setcookie() function.
3. Destroy the session object with the session_destroy() function.

Below is a good sample script:

<?php
session_start();
$_SESSION = array();
if (isset($_COOKIE[session_name()])) {
setcookie(session_name(), '', time()-42000, '/');
}
session_destroy();
print("<html><pre>");
print("Thank you for visiting PICKZYCenter.com.\n");
print(" <a href=login.php>Login Again.</a>\n");
print("</pre></html>\n");


?>

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