PHP Interview Questions And Answers For Experienced

PHP Interview Questions And Answers For Experienced

1.How can I execute a PHP script using command line ?
Answer: Just run the PHP CLI (Command Line Interface) program and provide the PHP script file name as the command line argument. For example, “php myScript.php”, assuming “php” is the command to invoke the CLI program.
Be aware that if your PHP script was written for the Web CGI interface, it may not execute properly in command line environment.

2.What is use of header() function in php ?
Answer: In PHP Important to notice the Limitation of HEADER() function is that header() must be called before any actual output is send. Means must use header function before HTML or any echo stateament
There are Number of Use of HEADER() function in php like below
1The header() function use to sends a raw HTTP header to a client.
2We can use herder() function for redirection of pages.
3Use for refresh the page on given time interval automatically.
4To send email header content like cc, bcc , reply to etc data and lot more.

3.WHAT ARE THE DIFFERENT TYPES OF ERRORS IN PHP?
Answer: Here are three basic types of runtime errors in PHP:

1. Notices: These are trivial, non-critical errors that PHP encounters while executing a script – for example, accessing a variable that has not yet been defined. By default, such errors are not displayed to the user at all – although you can change this default behavior.
2. Warnings: These are more serious errors – for example, attempting to include() a file which does not exist. By default, these errors are displayed to the user, but they do not result in script termination.
3. Fatal errors: These are critical errors – for example, instantiating an object of a non-existent class, or calling a non-existent function. These errors cause the immediate termination of the script, and PHP’s default behavior is to display them to the user when they take place.

Internally, these variations are represented by twelve different error types.

4.What is properties of class?
Answer: Class member variables are called “properties”. We may also see them referred to using other terms such as “attributes” or “fields”, but for the purposes of this reference we will use “properties”. They are defined by using one of the keywords public, protected, or private, followed by a normal variable declaration. This declaration may include an initialization, but this initialization must be a constant value that is, it must be able to be evaluated at compile time and must not depend on run-time information in order to be evaluated.

5.Write the statement through which it can be added?
Answer: HTTP headers can be used in PHP by redirection which is written as:The headers can be added to HTTP response in PHP using the header(). The response headers are sent before any actual response being sent. The HTTP headers have to be sent before taking the output of any data. The statement above gets included at the top of the script.

6.How we use Custom errors and error triggers error handling method in PHP?
Answer: In Custom errors and error triggers,we handle errors by using self made functions.
1.Custom errors : By using this can handle the multiple errors that gives multiple message.
Syntax:
set_error_handler(\\\”Custom_Error\\\”);
In this syntax if we want that our error handle, handle
only one error than we write only one argument otherwise
for handle multiple errors we can write multiple arguments.

Example:
//function made to handle errorfunction
custom_Error($errorno, $errorstr)
{
echo \\\”Error: [$errorno] $errorstr\\\”;  }
//set error handler like that
set_error_handler(\\\”custom_Error\\\”);
//trigger to that error
echo($verify);?>

2.error trigger : In PHP we use error trigger to handle
those kind of error when user enter some input data.If
data has an error than handle by error trigger function.
Syntax:

$i=0;if ($i<=1)
{
trigger_error(\\\”I should be greater than 1 \\\”);
}
?>
In this trigger_error function generate error when i is less than or greater than 1.

7.What is the difference b/w isset and empty?
Answer: The main difference b/w isset and empty are given below:
isset: This variable is used to handle functions and checked a variable is set even through it is empty.
empty: This variable is used to handle functions and checked either variable has a value or it is an empty string,zero0 or not set at all.

8.What is the difference between static and Dynamic Web Sites?
Answer: The Web sites were made up of a collection of documents written in the HTML language. The pages were text based, simple, and static. Every time the user reloaded a page in his or her browser, it looked exactly the same. It consisted of HTML text, images, and links.
A dynamic Web site is one with content that is regenerated every time a user visits or reloads the site. Although it can be as simple as displaying the current date and time, in most cases it requires the use of a database, which contains the site?s information, and a scripting language that can retrieve the information from the database. Google and Yahoo! are examples of dynamic sites, search engines that create customized pages based on a key word or phrase you type.

9.What is Session Id?
Answer: A session ID is an identification string of a session. Since there might be multiple visitors coming to your Web site at the same time, the PHP engine needs to maintain multiple sessions concurrently. Session IDs are created and maintained by the PHP engine to identify sessions.

10.What is the difference between the functions unlink and unset?
Answer: unlink() is a function for file system handling. It will simply delete the file in context.
unset() is a function for variable management. It will make a variable undefined.