1) What is
PHP?
PHP is a web language based on scripts that
allows developers to dynamically create generated web pages.
2) What does
the initials of PHP stand for?
PHP means PHP: Hypertext Preprocessor.
3) Which
programming language does PHP resemble to?
PHP syntax resembles Perl and C
4) What does
PEAR stands for?
PEAR means “PHP Extension and Application
Repository”. it extends PHP and provides a higher level of programming for web
developers.
5) What is
the actually used PHP version?
Version 5 is the actually used version of
PHP.
6) How do
you execute a PHP script from the command line?
Just use the PHP command line interface (CLI)
and specify the file name of the script to be executed as follows:
1
|
php script.php
|
7) 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
|
18) What are
the correct and the most two common way to start and finish a PHP block of
code?
The two most
common ways to start and finish a PHP script are: <?php [ — PHP
code—- ] ?> and <? [— PHP
code —] ?>
9) How can
we display the output directly to the browser?
To be able to display the output directly to
the browser, we have to use the special tags <?= and ?>.
10) What is
the main difference between PHP 4 and PHP 5?
PHP 5 presents many additional OOP (Object
Oriented Programming) features.
11) Is
multiple inheritance supported in PHP?
PHP includes only single inheritance, it
means that a class can be extended from only one single class using the keyword
‘extended’.
12) 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
overrided.
13) How
comparison of objects is done in PHP5?
We use the operator ‘==’ to test is two
object are instanced from the same class and have same attributes and equal
values. We can test if two object are refering to the same instance of the same
class by the use of the identity operator ‘===’.
14) How can
PHP and HTML interact?
It is possible to generate HTML through PHP
scripts, and it is possible to pass informations from HTML to PHP.
15) What
type of operation is needed when passing values through a form or an URL?
If we would like to pass values througn a
form or an URL then we need to encode and to decode them using
htmlspecialchars() and urlencode().
16) How can
PHP and Javascript interact?
PHP and Javascript cannot directly interacts
since PHP is a server side language and Javascript is a client side language.
However we can exchange variables since PHP is able to generate Javascript code
to be executed by the browser and it is possible to pass specific variables
back to PHP via the URL.
17) What is
needed to be able to use image function?
GD library is needed to be able execute image
functions.
18) What is
the use of the function ‘imagetypes()’?
imagetypes() gives the image format and types
supported by the current version of GD-PHP.
19) What are
the functions to be used to get the image’s properties (size, width and
height)?
The functions are getimagesize() for size,
imagesx() for width and imagesy() for height.
20) How
failures in execution are handled with include() and require() functions?
If the function require() cannot access to
the file then it ends with a fatal error. However, the include() function gives
a warning and the PHP script continues to execute.
21) What is
the main difference between require() and require_once()?
require() and require_once() perform the same
task except that the second function checks if the PHP script is already
included or not before executing it.
(same for include_once() and include())
22) How can
I display text with a PHP script?
Two methods are possible:
<!--?php echo "Method 1"; print "Method 2"; ?-->
23) How can
we display information of a variable and readable by human with PHP?
To be able to display a human-readable result
we use print_r().
24) How is
it possible to set an infinite execution time for PHP script?
The set_time_limit(0) added at the beginning
of a script sets to infinite the time of execution to not have the PHP error
‘maximum execution time exceeded’.It is also possible to specify this in the
php.ini file.
25) What does the PHP error ‘Parse error in
PHP – unexpected T_variable at line x’ means?
This is a PHP syntax error expressing that a
mistake at the line x stops parsing and executing the program.
26) What
should we do to be able to export data into an Excel file?
The most common and used way is to get data
into a format supported by Excel. For example, it is possible to write a .csv
file, to choose for example comma as separator between fields and then to open
the file with Excel.
27) What is
the function file_get_contents() usefull for?
file_get_contents() lets reading a file and
storing it in a string variable.
28) How can
we connect to a MySQL database from a PHP script?
To be able to connect to a MySQL database, we
must use mysql_connect() function as follows:
or
<!--?php $database = mysql_connect("HOST", "USER_NAME", "PASSWORD");
mysql_select_db("DATABASE_NAME",$database); ?-->
29) What is
the function mysql_pconnect() usefull for?
mysql_pconnect() ensure a persistent
connection to the database, it means that the connection do not close when the
the PHP script ends.
30) How the
result set of Mysql be handled in PHP?
The result set can be handled using
mysql_fetch_array, mysql_fetch_assoc, mysql_fetch_object or mysql_fetch_row.
31) How is
it possible to know the number of rows returned in result set?
The function mysql_num_rows() returns the
number of rows in a result set.
32) Which
function gives us the number of affected entries by a query?
mysql_affected_rows() return the number of
entries affected by an SQL query.
33) What is
the difference between mysql_fetch_object() and mysql_fetch_array()?
The mysql_fetch_object() function collects
the first single matching record where mysql_fetch_array() collects all
matching records from the table in an array.
34) How can
we access the data sent through the URL with the GET method?
In order to access the data sent via the GET
method, we you use $_GET array like this:
www.url.com?var=value
$variable = $_GET[“var”]; this will now
contain ‘value’
35) How can
we access the data sent through the URL with the POST method?
To access the data sent this way, you use the
$_POST array.
Imagine you have a form field called ‘var’ on
the form, when the user clicks submit to the post form, you can then access the
value like this:
$_POST[“var”];
36) How can
we check the value of a given variable is a number?
It is possible to use the dedicated function,
is_numeric() to check whether it is a number or not.
37) How can
we check the value of a given variable is alphanumeric?
It is possible to use the dedicated function,
ctype_alnum to check whether it is an alphanumeric value or not.
38) How do I
check if a given variable is empty?
If we want to check whether a variable has a
value or not, it is possible to use the empty() function.
39) What
does the unlink() function means?
The unlink() function is dedicated for file
system handling. It simply deletes the file given as entry.
40) What
does the unset() function means?
The unset() function is dedicated for
variable management. It will make a variable undefined.
41) How do I
escape data before storing it into the database?
addslashes function enables us to escape data
before storage into the database.
42) How is
it possible to remove escape characters from a string?
The stripslashes function enables us to
remove the escape characters before apostrophes in a string.
43) How can
we automatically escape incoming data?
We have to enable the Magic quotes entry in
the configuration file of PHP.
44) What
does the function get_magic_quotes_gpc() means?
The function get_magic_quotes_gpc() tells us
whether the magic quotes is switched on or no.
45) Is it
possible to remove the HTML tags from data?
The strip_tags() function enables us to clean
a string from the HTML tags.
46) what is
the static variable in function useful for?
A static variable is defined within a
function only the first time and its value can be modified during function
calls as follows:
<!--?php function testFunction() { static $testVariable = 1;
echo $testVariable; $testVariable++; } testFunction();
or
<!--?php function testFunction() { static
$testVariable = 1; echo $testVariable; $testVariable++; } testFunction(); //1 testFunction(); //2 testFunction(); //3 ?-->
47) How can
we define a variable accessible in functions of a PHP script?
This feature is possible using the global
keyword.
48) How is
it possible to return a value from a function?
A function returns a value using the
instruction ‘return $value;’.
49) What is
the most convenient hashing method to be used to hash passwords?
It is preferable to use crypt() which
natively supports several hashing algorithms or the function hash() which
supports more variants than crypt() rather than using the common hashing
algorithms such as md5, sha1 or sha256 because they are conceived to be fast.
hence, hashing passwords with these algorithms can vulnerability.
50) Which
cryptographic extension provide generation and verification of digital
signatures?
The PHP-openssl extension provides several
cryptographic operations including generation and verification of digital
signatures.
51) How a
constant is defined in a PHP script?
The define() directive lets us defining a
constant as follows:
define (“ACONSTANT”, 123);
52) How can
you pass a variable by reference?
To be able to pass a variable by reference,
we use an ampersand in front of it, as follows $var1 = &$var2
53) Will a
comparison of an integer 12 and a string “13” work in PHP?
“13” and 12 can be compared in PHP since it
casts everything to the integer type.
54) How is
it possible to cast types in PHP?
The name of the output type have to be
specified in parentheses before the variable which is to be cast as follows:
* (int), (integer) – cast to integer
* (bool), (boolean) – cast to boolean
* (float), (double), (real) – cast to float
* (string) – cast to string
* (array) – cast to array
* (object) – cast to object
55) When a
conditional statement is ended with an endif?
When the original if was followed by : and
then the code block without braces.
56) How is
the ternary conditional operator used in PHP?
It is composed of three expressions: a
condition, and two operands describing what instruction should be performed
when the specified condition is true or false as follows:
Expression_1 ? Expression_2 : Expression_3;
57) What is
the function func_num_args() used for?
The function func_num_args() is used to give
the number of parameters passed into a function.
58) If the
variable $var1 is set to 10 and the $var2 is set to the character var1, what’s
the value of $$var2?
$$var2 contains the value 10.
59) What
does accessing a class via :: means?
:: is used to access static methods that do
not require object initialization.
60) In PHP,
objects are they passed by value or by reference?
In PHP, objects passed by value.
61) Are
Parent constructors called implicitly inside a class constructor?
No, a parent constructor have to be called
explicitly as follows:
parent::constructor($value)
62) What’s
the difference between __sleep and __wakeup?
__sleep returns the array of all the
variables that need to be saved, while __wakeup retrieves them.
63) What is
faster?
1- Combining two variables as follows:
$variable1 = ‘Hello ‘;
$variable2 = ‘World’;
$variable3 = $variable1.$variable2;
Or
2- $variable3 = “$variable1$variable2”;
$variable3 will contain “Hello World”. The
first code is faster than the second code especially for large large sets of
data.
64) what is
the definition of a session?
A session is a logical object enabling us to
preserve temporary data across multiple PHP pages.
65) How to
initiate a session in PHP?
The use of the function session_start() lets
us activating a session.
66) How is
it possible to propagate a session id?
It is possible to propagate a session id via
cookies or URL parameters.
67) What is
the meaning of a Persistent Cookie?
A persistent cookie is permanently stored in
a cookie file on the browser’s computer. By default, cookies are temporary and
are erased if we close the browser.
68) When
sessions ends?
Sessions automatically ends when the PHP
script finishs executing, but can be manually ended using the
session_write_close().
69) What is
the difference between session_unregister() and session_unset()?
The session_unregister() function unregister
a global variable from the current session and the session_unset() function free
all session variables.
70) What
does $GLOBALS means?
$GLOBALS is associative array including
references to all variables which are currently defined in the global scope of
the script.
71) What
does $_SERVER means?
$_SERVER is an array including information
created by the web server such as paths, headers, and script locations.
72) What
does $_FILES means?
$_FILES is an associative array composed of
items sent to the current script via the HTTP POST method.
73) What is
the difference between $_FILES[‘userfile’][‘name’] and
$_FILES[‘userfile’][‘tmp_name’]?
$_FILES[‘userfile’][‘name’] represents the
original name of the file on the client machine,
$_FILES[‘userfile’][‘tmp_name’] represents
the temporary filename of the file stored on the server.
74) How can
we get the error when there is a problem to upload a file?
$_FILES[‘userfile’][‘error’] contains the
error code associated with the uploaded file.
75) How can
we change the maximum size of the files to be uploaded?
We can change the maximum size of files to be
uploaded by changing upload_max_filesize in php.ini.
76) What
does $_ENV means?
$_ENV is an associative array of variables
sent to the current PHP script via the environment method.
77) What
does $_COOKIE means?
$_COOKIE is an associative array of variables
sent to the current PHP script using the HTTP Cookies.
78) What
does the scope of variables means?
The scope of a variable is the context within
which it is defined. For the most part all PHP variables only have a single
scope. This single scope spans included and required files as well.
79) what the
difference between the ‘BITWISE AND’ operator and the ‘LOGICAL AND’ operator?
$a and $b:
TRUE if both $a and $b are TRUE.
$a & $b: Bits that are set in both $a and $b are
set.
80) What are
the two main string operators?
The first is the concatenation operator
(‘.’), which returns the concatenation of its right and left arguments. The
second is (‘.=’), which appends the argument on the right to the argument on
the left.
81) What
does the array operator ‘===’ means?
$a === $b TRUE if $a and $b have the same
key/value pairs in the same order and of the same types.
82) What is
the differences between $a != $b and $a !== $b?
!= means inequality (TRUE if $a is not equal
to $b) and !== means non-identity (TRUE if $a is not identical to $b).
83) How can
we determine whether a PHP variable is an instantiated object of a certain
class?
To be able to verify whether a PHP variable
is an instantiated object of a certain class we use instanceof.
84) What is
the goto statement useful for?
The goto statement can be placed to enable
jumping inside the PHP program. The target is pointed by a label followed by a
colon, and the instruction is specified as a goto statement followed by the
desired target label.
85) What is
the difference between
Exception::getMessage and Exception::getLine ?
Exception::getMessage lets us getting the
Exception message and Exception::getLine lets us getting the line in which the
exception occurred.
86) What
does the expression Exception::__toString means?
Exception::__toString gives the String
representation of the exception.
87) How is
it possible to parse a configuration file?
The function parse_ini_file() enables us to
load in the ini file specified in filename, and returns the settings in it in
an associative array.
88) How can
we determine whether a variable is set?
The boolean function isset determines if a
variable is set and is not NULL.
89) What is
the difference between the functions strstr() and stristr()?
The string function strstr(string allString,
string occ) returns part of allString from the first occurrence of occ to the
end of allString. This function is case-sensitive. stristr() is identical to
strstr() except that it is case insensitive.
90) what is
the difference between for and foreach?
for is expressed as follows:
for (expr1; expr2; expr3)
Statement
The first expression is executed once at the
beginning. In each iteration, expr2 is evaluated. If it is TRUE, the loop
continues and the statements inside for are executed. If it evaluates to FALSE,
the execution of the loop ends. expr3 is tested at the end of each iteration.
However, foreach provides an easy way to
iterate over arrays and it is only used with arrays and objects.
91) Is it
possible to submit a form with a dedicated button?
It is possible to use the
document.form.submit() function to submit the form. For example: <input
type=button value=”SUBMIT” onClick=”document.form.submit()”>
92) What is
the difference between ereg_replace() and eregi_replace()?
The function eregi_replace() is identical to
the function ereg_replace() except that it ignores case distinction when
matching alphabetic characters.
93) Is it
possible to protect special characters in a query string?
Yes, we use the urlencode() function to be
able to protect special characters.
94) What are
the three classes of errors that can occur in PHP?
The three basic classes of errors are notices
(non-critical), warnings (serious errors) and fatal errors (critical errors).
95) What is
the difference between characters \034 and \x34?
\034 is octal 34 and \x34 is hex 34.
96) How can
we pass the variable through the navigation between the pages?
It is possible to pass the variables between
the PHP pages using sessions, cookies or hidden form fields.
97) Is it
possible to extend the execution time of a php script?
The use of the set_time_limit(int seconds)
enables us to extend the execution time of a php script. The default limit is
30 seconds.
98) Is it
possible to destroy a cookie?
Yes, it is possible by setting the cookie
with a past expiration time.
99) What is
the default session time in php?
The default session time in php is until
closing of browser
100) Is it
possible to use COM component in PHP?
Yes, it’s possible to integrate (Distributed)
Component Object Model components ((D)COM) in PHP scripts which is provided as
a framework.
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