yahoo interview questions and answers - Wikitechy

What is the error message that you would get if you try to assign “Null” to an integer variable ?

Editor — Thu, 22 Jul 2021 07:48:17 +0000

What is the error message that you would get if you try to assign “Null” to an integer variable ?

Error message : Cannot convert null to int because it is a non-nullable value type(or) INVALID use of NULL.

What is the difference between shell script and perl ?

Editor — Thu, 22 Jul 2021 04:09:14 +0000

What is the difference between shell script and perl ?

Shell Script	Perl
Shell script is a dependent platform only for Unix OS.	Perl is OS independent.
Shell script is a scripting language.	Perl is a programming language.
Scripting language need not be compliled.	Perl compiles the program before executing the script.
Shell Scripting using one or more built-in scripting languages.	Perl using only one scripting language.

Explain about error handling in php ?

Editor — Wed, 21 Jul 2021 13:14:32 +0000

Explain about error handling in php ?

Error handling is the process of catching errors elevated from program and then taking correct action. If you would handle errors then the most common error checking methods given in PHP.
- die() function
- Custom errors and error triggers
- Error reporting

die() function

To write the PHP program you should check all possible error condition before checking and take appropriate action when required.
The following example without having /tmp/test.xt file and with this file.

   if(!file_exists("/tmp/test.txt")) {
      die("File not found");
   }else {
      $file = fopen("/tmp/test.txt","r");
      print "Opend file sucessfully";
   }
   // Test of the code here.
?>

Custom errors and error triggers

We can write own function to handling any error. PHP provides a framework to define error handling function.
This function must be able to handle a minimum of two parameters (error level and error message) but can accept up to five parameters (optionally: file, line-number, and the error context)

Syntax

error_function(error_level,error_message, error_file,error_line,error_context);

Error reporting

These error report levels are the different types of error the user-defined error handler can be used.
The errors are .E_ERROR, E_WARNING, E_PARSE, E_NOTICE, E_CORE_ERROR, E_CORE_WARNING, E_USER_ERROR, E_USER_WARNING, E_USER_NOTICE, E_STRICT, E_RECOVERABLE_ERROR, E_ALL
These all errors handle to using set_error_handler function.

 
   error_reporting( E_ERROR );
   
   function handleError($errno, $errstr,$error_file,$error_line) {
      echo "Error: [$errno] $errstr - $error_file:$error_line";
      echo "
";
      echo "Terminating PHP Script";
      
      die();
   }
   
   //set error handler
   set_error_handler("handleError");
   
   //trigger error
   myFunction();
?>

How to find out, how a user visited a particular page ?

Editor — Wed, 21 Jul 2021 13:11:09 +0000

How to find out, how a user visited a particular page ?

We add a counter in that page.
When a page load that counter value will increase.
For storing its previous value we can use session, database etc.

$counter++;
?>

What is the default port for MySQL Server ?

Editor — Tue, 20 Jul 2021 08:18:59 +0000

What is the default port for MySQL Server ?

If you want to check the port number just type status on the MySQL command prompt. It would display all the server details along with the Port number.(default port is 3306).

What does the top command display ?

Editor — Mon, 19 Jul 2021 15:02:27 +0000

What does the top command display ?

Top Command display is the top processes on the system and periodically updates the information.
Top command displays:
- Process ID.
- Username.
- Priority of Task.
- Nice value of a task.
- Amount of virtual memory used by task.
- Resident size (non swapped physical memory used by task).
- Amount of shared memory used by task.
- Process status(whether sleep or running).
- Share of physical memory usage.
- CPU time (in Hundredths) and
- Command or program used or using.

What is mutation testing ?

Editor — Sun, 18 Jul 2021 18:08:15 +0000

Mutation Testing is a software testing where we mutate (change) certain statements in the source code and check if the test cases are able to find the errors.
It is a type of White Box Testing which is mainly used for Unit Testing.
The changes in mutant program are kept extremely small, so it does not affect the overall objective of the program.
The aim of Mutation Testing is to assess the quality of the test cases which should be robust enough to fail mutant code. This method is also called as Fault based testing strategy as it includes creating fault in the program.
Mutation Testing is widely used for languages such as Java and XML.

What is Mutation Testing

Benefits of Mutation Testing

Mutation Testing carries a entire new kind of errors to the developer’s attention.
Mutation Testing is the most powerful method to detect hidden defects, which might be impossible to identify using the conventional testing techniques.
Tools such as Insure++ help us to find defects in the code using the state of the art.
Increased customer fulfillment index as the product would be a smaller amount of errors.
Debugging and Maintaining the product would be more easier than ever.

Is running apache as a root is a security risk ?

Editor — Sun, 11 Jul 2021 13:46:25 +0000

Is running apache as a root is a security risk ?

Yes, running the apache as root is security issue. An attacker can manages to compromise and get access to a website. Once they entered they will gain full root (admin) access to the entire server.