Crake a PHP interview questions and answers of part 2

 Dear All,

16. What is the difference between a function and a method in PHP?

A function is a piece of code that can be called from anywhere in a script, while a method is a function that belongs to a specific object of a class and can only be called on that object.

17. What is the difference between the array_merge and array_combine functions in PHP?

The array_merge function takes two or more arrays and merges them into a single array. The resulting array contains all the values of the original arrays. The array_combine function takes two arrays and combines them into a single associative array. The first array contains the keys of the new array, and the second array contains the values.

18. What is the use of the array_diff function in PHP?

The array_diff function is used to compare two or more arrays and return the values that are present in the first array but not in the others. It takes two or more arrays as input and returns an array with the values that are unique to the first array.

19. What is the difference between require_once and include_once in PHP?

The require_once and include_once functions are similar to require and include, but they ensure that the file is included only once. If the file has already been included, PHP will not include it again. The difference between require_once and include_once is that require_once generates a fatal error if the file cannot be found, while include_once generates a warning.

20. What is the use of the count function in PHP?

The count function is used to count the number of elements in an array or the number of characters in a string. It takes an array or string as input and returns the number of elements or characters.

21. What is the use of the array_search function in PHP?

The array_search function is used to search an array for a specific value and return the key of the first matching element. It takes two parameters: the value to search for and the array to search.

22. What is the difference between urlencode and rawurlencode in PHP?

The urlencode function encodes a string for use in a URL, replacing any special characters with their corresponding percent-encoded values. The rawurlencode function is similar, but it encodes all characters except letters, digits, and a few special characters.

23. What is the use of the preg_match function in PHP?

The preg_match function is used to perform a regular expression match on a string. It takes two parameters: the regular expression pattern to search for and the string to search. If a match is found, the function returns true, otherwise it returns false.

24. What is the difference between a static and a constant variable in PHP?

A static variable is a variable that retains its value between function calls. It is declared using the static keyword. A constant variable is a variable whose value cannot be changed during the execution of a script. It is declared using the const keyword.

25. What is the use of the file_get_contents function in PHP?

The file_get_contents() function is used to read the contents of a file into a string. It takes one parameter, which is the path to the file to be read.

26. What is the use of the header function in PHP?

The header() function is used to send HTTP headers to the browser. These headers can be used to set the content type, set cookies, and redirect the browser to another page.

27. What is the difference between a single quote and a double quote in PHP?

In PHP, single quotes are used to define a string literal, while double quotes allow for the interpolation of variables and escape sequences within the string.

28. What is the difference between array_push and array_pop in PHP?

array_push is used to add one or more elements to the end of an array, while array_pop is used to remove and return the last element of an array.

29. What is the use of the header() function with a location parameter in PHP?

The header() function with a location parameter is used to redirect the user to a different page. It sends a 302 (temporary) or 301 (permanent) redirect header to the client, telling it to request the new page.

30. What is the use of the explode function in PHP?

The explode() function is used to split a string into an array, using a specified delimiter to determine where to split the string.

31 .What is the use of the empty function in PHP?

The empty() function is used to determine if a variable is empty. It returns true if the variable is NULL, false, an empty string, an empty array, or has not been set.

32. What is the use of the session_start function in PHP?

The session_start() function is used to start a new or resume an existing session. Sessions are used to store and retrieve data between page requests, allowing for persistent user data.

33 .What is the use of the array_key_exists function in PHP?

The array_key_exists() function is used to check if a specified key exists in an array. It returns true if the key exists and false otherwise.

34 .What is the use of the count function in PHP?

The count() function is used to count the number of elements in an array or the number of characters in a string.