How is a constant defined in a PHP script?
The define() directive lets us defining a constant as follows:
define ("ACONSTANT", 123);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
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.
PHP Interview Question
How is it possible to cast types in PHP?
The name of the output type has 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
When is a conditional statement ended with endif?
When the original if was followed by: and then the code block without braces.
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;Advance PHP Interview Question
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.
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.
What does accessing a class via :: means?
:: is used to access static methods that do not require object initialization.
PHP Interview Question
In PHP, objects are they passed by value or by reference?
In PHP, objects are passed by reference.
Are Parent constructors called implicitly inside a class constructor?
No, a parent constructor have to be called explicitly as follows:
parent::constructor($value)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.
Advance PHP Interview Question
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.
What is the definition of a session?
A session is a logical object enabling us to preserve temporary data across multiple PHP pages.
How to initiate a session in PHP?
The use of the function session_start() lets us activating a session.
PHP Interview Question
How can you propagate a session id?
You can propagate a session id via cookies or URL parameters.
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.
When do sessions end?
Sessions automatically end when the PHP script finishes executing but can be manually ended using the session_write_close().
Advance PHP Interview Question
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 frees all session variables.
What does $GLOBALS mean?
$GLOBALS is associative array including references to all variables which are currently defined in the global scope of the script.
What does $_SERVER mean?
$_SERVER is an array including information created by the web server such as paths, headers, and script locations.
PHP Interview Question
What does $_FILES means?
$_FILES is an associative array composed of items sent to the current script via the HTTP POST method.
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.
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.
Advance PHP Interview Question
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.
What does $_ENV mean?
$_ENV is an associative array of variables sent to the current PHP script via the environment method.
What does $_COOKIE mean?
$_COOKIE is an associative array of variables sent to the current PHP script using the HTTP Cookies.
PHP Interview Question
What does the scope of variables mean?
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.
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.
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.
Advance PHP Interview Question
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.
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).
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 instance of.
PHP Interview Question
What is the go to statement useful for?
The go to 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.
What is the difference between Exception::get Message and Exception:: gantline?
Exception::get Message lets us getting the Exception message and Exception::gantline lets us getting the line in which the exception occurred.
What does the expression Exception::__to String means?
Exception::__to String gives the String representation of the exception.
Advance PHP Interview Question
How is it possible to parse a configuration file?
The function parse_ini_file() enables us to load in the in file specified in filename and returns the settings in it in an associative array.
How can we determine whether a variable is set?
The Boolean function is set determines if a variable is set and is not NULL.
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.
PHP Interview Question
What is the difference between for and for each?
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, for each provides an easy way to iterate over arrays, and it is only used with arrays and objects.
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()”>
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.
Advance PHP Interview Question
Is it possible to protect special characters in a query string?
Yes, we use the urlencode() function to be able to protect special characters.
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).
What is the difference between characters \034 and \x34?
\034 is octal 34 and \x34 is hex 34.
PHP Interview Question
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.
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.
Is it possible to destroy a cookie?
Yes, it is possible by setting the cookie with a past expiration time.
Advance PHP Interview Question
What is the default session time in PHP?
The default session time in php is until the closing of the browser
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.
