PHP Interview Questions And Answers Related To Build-In Functions

PHP, or Hypertext Preprocessor, is a widely-used programming language for web development. In this blog post, we’ll go over some of the most commonly asked PHP interview questions and provide answers to help you prepare for your next interview.


Questions!

1. What is PHP and what is it used for?

PHP is a server-side scripting language used for web development. It is used to create dynamic web pages and can be embedded into HTML.

2. How does PHP handle variables?

PHP automatically determines the data type of a variable based on the value assigned to it. Variables in PHP are represented by a dollar sign ($), followed by the variable name.

What is the difference between a static and a dynamic website?

A static website is one that has fixed content and does not change, while a dynamic website has content that can change based on user input or other factors. PHP is often used to create dynamic websites.

What are some common uses of PHP?

PHP is commonly used for creating login forms, image galleries, and forums. It can also be used to connect to and retrieve data from a database, such as MySQL.

How does PHP handle errors?

PHP has built-in error handling functions, such as the “error_reporting” function, which can be used to control the level of error reporting. Additionally, the “try” and “catch” statements can be used to handle exceptions.

What is the difference between GET and POST methods in PHP?

The GET method is used to retrieve data from a server, while the POST method is used to send data to a server. GET requests can be cached and bookmarked, while POST requests cannot.

How do you connect to a database in PHP?

The “mysqli” or “PDO” extension can be used to connect to a MySQL database in PHP. The “mysqli_connect” or “PDO::__construct” function is used to establish a connection, and then various functions can be used to execute SQL statements and retrieve data.

How do you create a session in PHP?

The “session_start” function is used to start a new session or resume an existing one. Once a session has been started, session variables can be set and accessed using the $_SESSION superglobal array.

What is the difference between include and require in PHP?

Both “include” and “require” are used to include a file into a PHP script. However, if the file cannot be found, the “include” statement will produce a warning, while the “require” statement will produce a fatal error, halting the execution of the script.

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

The “==” operator is used to compare values, while the “===” operator is used to compare values and data types. For example, “1 == ‘1’” would be true, but “1 === ‘1’” would be false.

What is the difference between echo and print in PHP?

Both “echo” and “print” are used to output data in PHP. However, “echo” is slightly faster than “print” and does not return a value.

What is the difference between unset and unlink in PHP?

“unset” is used to destroy a variable, while “unlink” is used to delete a file.

What is the use of the isset function in PHP?

The “isset” function is used to check if a variable has been set, or if it has a value. It returns a boolean value of true if the variable is set and false if it is not.

What is the use of the empty function in PHP?

The “empty” function is used to check if a variable is empty or not. It returns a boolean value of true if the variable is empty and false if it contains a value.

What is the use of the is_numeric function in PHP?

The “is_numeric” function is used to check if a variable contains a numeric value or not. It returns a boolean value of true if the variable contains a numeric value and false if it does not.

What is the use of the strlen function in PHP?

The “strlen” function is used to find the length of a string. It returns the number of characters in a string.

What is the use of the explode function in PHP?

The “explode” function is used to split a string into an array. It takes two parameters, the first is the delimiter and the second is the string.

What is the use of the implode function in PHP?

The “implode” function is used to join elements of an array into a single string. It takes two parameters, the first is the delimiter and the second is the array.

What is the use of the array_merge function in PHP?

The “array_merge” function is used to merge two or more arrays into one. It takes any number of arrays as parameters and returns a new array containing all the elements of the original arrays.

What is the use of the in_array function in PHP?

The “in_array” function is used to check if a value exists in an array. It takes two parameters, the first is the value to search for and the second is the array. It returns a boolean value of true if the value is found and false if it is not.

What is the use of the array_search function in PHP?

The “array_search” function is used to search for a value in an array. It takes two parameters, the first is the value to search for and the second is the array. It returns the key of the value if it is found and false if it is not.

What is the use of the sort function in PHP?

The “sort” function is used to sort the elements of an array in ascending order. It takes the array as a parameter and sorts it in place, meaning that the original array is modified.

What is the use of the rsort function in PHP?

The “rsort” function is used to sort the elements of an array in descending order. It takes the array as a parameter and sorts it in place, meaning that the original array is modified.

What is the use of the count function in PHP?

The “count” function is used to count the number of elements in an array. It takes the array as a parameter and returns the number of elements.

What is the use of the array_keys function in PHP?

The “array_keys” function is used to return all the keys of an array. It takes the array as a parameter and returns a new array containing all the keys.

What is the use of the array_values function in PHP?

The “array_values” function is used to return all the values of an array. It takes the array as a parameter and returns a new array containing all the values.

What is the use of the array_unique function in PHP?

The “array_unique” function is used to remove duplicate values from an array. It takes the array as a parameter and returns a new array with all duplicate values removed.

What is the use of the array_slice function in PHP?

The “array_slice” function is used to extract a portion of an array. It takes three parameters, the first is the array, the second is the starting index, and the third is the number of elements to extract. It returns a new array containing the extracted elements.

What is the use of the array_combine function in PHP?

The “array_combine” function is used to create an array by using one array for keys and another for its values. It takes two arrays as parameters and returns a new array with the keys and values combined.

What is the use of the array_reverse function in PHP?

The “array_reverse” function is used to reverse the order of the elements in an array. It takes the array as a parameter and returns a new array with the elements in reverse order.

What is the use of the array_sum function in PHP?

The “array_sum” function is used to calculate the sum of the values in an array. It takes the array as a parameter and returns the sum of the values.

What is the use of the array_count_values function in PHP?

The “array_count_values” function is used to count the number of occurrences of each value in an array. It takes the array as a parameter and returns an array with the values as keys and their count as values.

What is the use of the array_replace function in PHP?

The “array_replace” function is used to replace the values of an array with the values from one or more other arrays. It takes at least two arrays as parameters and returns a new array with the replaced values.

What is the use of the array_walk function in PHP?

The “array_walk” function is used to apply a user-defined function to each element of an array. It takes two parameters, the first is the array and the second is the function to apply.

What is the use of the array_map function in PHP?

The “array_map” function is used to apply a user-defined function to each element of an array and return the result in a new array. It takes two parameters, the first is the function to apply and the second is the array.

What is the use of the array_filter function in PHP?

The “array_filter” function is used to filter the elements of an array based on a user-defined function. It takes two parameters, the first is the array and the second is the function to use as a filter.

What is the use of the array_reduce function in PHP?

The “array_reduce” function is used to apply a user-defined function to an array and reduce it to a single value. It takes two parameters, the first is the array and the second is the function to use for reducing.

What is the use of the array_chunk function in PHP?

The “array_chunk” function is used to split an array into smaller arrays of a specified size. It takes two parameters, the first is the array and the second is the size of the chunks.

What is the use of the array_key_exists function in PHP?

The “array_key_exists” function is used to check if a specific key exists in an array. It takes two parameters, the first is the key to check for and the second is the array. It returns a boolean value of true if the key exists and false if it does not.

What is the use of the shuffle function in PHP?

The “shuffle” function is used to randomly shuffle the elements of an array. It takes the array as a parameter and shuffles it in place, meaning that the original array is modified.

These are some of the most commonly asked PHP built-in functions related interview questions. By understanding the concepts and functions behind these questions, you’ll be well-prepared for your next interview. Remember to also practice with real-world examples and be prepared to explain your thought process and reasoning behind your answers.

You can always visit official PHP Doc.

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