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PHP interview questions

PHP interview questions.

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  • 1.

    What is the use of ini_set()?

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  • 2.

    What is the difference between == and ===?

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  • 3.

    What is the return type of a function that doesn't return anything?

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  • 4.

    What does $GLOBALS mean?

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  • 5.

    What are the keys & values in an indexed array?

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  • 6.

    What is the purpose of php.ini file?

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  • 7.

    How can you pass a variable by reference?

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  • 8.

    Is multiple inheritance supported in PHP?

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  • 9.

    What is stdClass in PHP?

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  • 10.

    In PHP, objects are they passed by value or by reference?

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  • 11.

    What is PDO in PHP?

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  • 12.

    Is there a difference between isset and !empty?

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  • 13.

    Differentiate between echo and print()

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  • 14.

    What is the differences between $a != $b and $a !== $b?

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  • 15.

    What does the 'var' keyword mean in PHP?

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  • 16.

    What do we mean by keys and values?

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  • 17.

    What are the differences between die() and exit() functions in PHP?

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  • 18.

    Explain what the different PHP errors are

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  • 19.

    Explain usage of enumerations in PHP

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  • 20.

    Explain how we handle exceptions in PHP?

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  • 21.

    What are the main differences between const vs define

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  • 22.

    What's the difference between isset() and array_key_exists()?

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  • 23.

    Can you extend a Final defined class?

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  • 24.

    What are PSRs? Choose 1 and briefly describe it.

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  • 25.

    How can you enable error reporting in PHP?

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  • 26.

    When should I use require vs. include?

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  • 27.

    What are the different scopes of variables?

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  • 28.

    What is the difference between var_dump() and print_r()?

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  • 29.

    What is the difference between single-quoted and double-quoted strings in PHP?

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  • 30.

    How is it possible to set an infinite execution time for PHP script?

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  • 31.

    Give me some real life examples when you had to use __destruct in your classes

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  • 32.

    Declare some function with default parameter

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  • 33.

    PHP array delete by value (not key)

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  • 34.

    Is there a function to make a copy of a PHP array to another?

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  • 35.

    Explain the difference between exec() vs system() vs passthru()?

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  • 36.

    Are Parent constructors called implicitly inside a class constructor?

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  • 37.

    Maximum how many arguments are allowed in a function in PHP?

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  • 38.

    What is the difference between PDO's query() vs execute()?

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  • 39.

    Explain the difference between shell_exec() and exec()

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  • 40.

    What is the difference between a PHP interpreter and a PHP handler?

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  • 41.

    Differentiate between exception and error

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  • 42.

    What exactly is the the difference between array_map, array_walk and array_filter?

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  • 43.

    What are the exception class functions?

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  • 44.

    What are some of the big changes PHP has gone through in the past few years?

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  • 45.

    Differentiate between parameterised and non parameterised functions

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  • 46.

    Why do we use extract()?

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  • 47.

    Explain function call by reference

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  • 48.

    What is the difference between using self and $this?

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  • 49.

    What is use of Null Coalesce Operator?

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  • 50.

    Does PHP support method overloading?

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  • 51.

    What is the difference between MySQL, MySQLi and PDO?

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  • 52.

    What is autoloading classes in PHP?

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  • 53.

    When should I use require_once vs. require?

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  • 54.

    Is there any reason to use strcmp() for strings comparison?

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  • 55.

    What will be returned by this code? Explain the result.

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  • 56.

    How do I pass variables and data from PHP to JavaScript?

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  • 57.

    Let's create Enumerations for PHP. Prove some code examples.

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  • 58.

    How would you create a Singleton class using PHP?

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  • 59.

    What does the following code output?

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  • 60.

    What will be returned by this code?

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  • 61.

    Check if PHP array is associative

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  • 62.

    Compare mysqli or PDO - what are the pros and cons?

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  • 63.

    Store an array as JSON or as a PHP serialized array?

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  • 64.

    What are the disadvantages of using persistent connection in PDO?

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  • 65.

    What exactly are late static bindings in PHP?

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  • 66.

    Explain the Exception Hierarchy introduced in PHP7

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  • 67.

    explain what is a closure in PHP and why does it use the “use” identifier?

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  • 68.

    What is use of Spaceship Operator?

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  • 69.

    What is the best method to merge two PHP objects?

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  • 70.

    Is PHP single or multi threaded?

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  • 71.

    How to turn errors into exceptions in PHP?

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  • 72.

    What does $$ mean?

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  • 73.

    What is the crucial difference between using traits versus interfaces?

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  • 74.

    What does yield mean in PHP?

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  • 75.

    What's better at freeing memory with PHP: unset() or $var = null?

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  • 76.

    Does PHP have threading?

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  • 77.

    Are PDO prepared statements sufficient to prevent SQL injection?

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  • 78.

    Explain the Order of Precedence for Traits in PHP

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  • 79.

    What does a $$$ mean in PHP?

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  • 80.

    How to measure execution times of PHP scripts?

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  • 81.

    How could we implement method overloading in PHP?

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  • 82.

    Provide some ways to mimic multiple constructors in PHP

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