PHP Arrays

Question 1

Q: What is an array in PHP?

Answer 1

A: A data structure that stores multiple values in a single variable.

Question 2

Q: What are the three types of arrays in PHP?

Answer 2

A: Indexed arrays, associative arrays, and multidimensional arrays.

Question 3

Q: How do you create an indexed array in PHP?

Answer 3

A: $array = array(“value1”, “value2”);.

Question 4

Q: How do you create an associative array in PHP?

Answer 4

A: $array = array(“key1” => “value1”, “key2” => “value2”);.

Question 5

Q: How do you access an element in an indexed array?

Answer 5

A: Use the index, e.g., $array[0];.

Question 6

Q: What function is used to get the length of an array?

Answer 6

A: count().

Question 7

Q: How do you check if a value exists in an array?

Answer 7

A: in_array($value, $array);.

Question 8

Q: How do you check if a key exists in an array?

Answer 8

A: array_key_exists($key, $array);.

Question 9

Q: What function is used to merge two arrays?

Answer 9

A: array_merge().

Question 10

Q: How do you add an element to the end of an array?

Answer 10

A: array_push($array, $value);.

Question 11

Q: What loop is commonly used to iterate over an array?

Answer 11

A: foreach.

Question 12

Q: How do you loop through an array with foreach?

Answer 12

foreach ($array as $value) {
// Code
}

Question 13

Q: How do you loop through an associative array with foreach?

Answer 13

foreach ($array as $key => $value) {
// Code
}

Question 14

Q: What function applies a callback to each array element?

Answer 14

A: array_map().

Question 15

Q: What function filters an array using a callback?

Answer 15

A: array_filter().

Question 16

Q: What function retrieves all the keys of an array?

Answer 16

A: array_keys().

Question 17

Q: What function retrieves all the values of an array?

Answer 17

A: array_values().

Question 18

Q: How do you combine two arrays into key-value pairs?

Answer 18

A: array_combine($keys, $values);.

Question 19

Q: How do you flip the keys and values of an array?

Answer 19

A: array_flip().

Question 20

Q: What function checks if a specific key exists in an array?

Answer 20

A: array_key_exists().

Question 21

Q: How do you sort an array by values in ascending order?

Answer 21

A: sort($array);.

Question 22

Q: How do you sort an array by values in descending order?

Answer 22

A: rsort($array);.

Question 23

Q: How do you sort an array by keys in ascending order?

Answer 23

A: ksort($array);.

Question 24

Q: How do you sort an associative array by values in ascending order?

Answer 24

A: asort($array);.

Question 25

Q: What function sorts an array using a custom comparison function?

Answer 25

A: usort().

Question 26

Q: How do you remove the last element of an array?

Answer 26

A: array_pop($array);.

Question 27

Q: How do you remove the first element of an array?

Answer 27

A: array_shift($array);.

Question 28

Q: How do you add an element to the beginning of an array?

Answer 28

A: array_unshift($array, $value);.

Question 29

Q: How do you slice a portion of an array?

Answer 29

A: array_slice($array, $offset, $length);.

Question 30

Q: How do you replace part of an array with another array?

Answer 30

A: array_splice($array, $offset, $length, $replacement);.

Question 31

Q: What function searches for a value and returns its key?

Answer 31

A: array_search($value, $array);.

Question 32

Q: What function checks if a value exists in an array?

Answer 32

A: in_array($value, $array);.

Question 33

Q: How do you find the index of the first occurrence of a value in an array?

Answer 33

A: Use array_search().

Question 34

Q: How do you get the first key of an array?

Answer 34

A: array_key_first($array);.

Question 35

Q: How do you get the last key of an array?

Answer 35

A: array_key_last($array);.

Question 36

Q: What is a multidimensional array?

Answer 36

A: An array containing one or more arrays as elements.

Question 37

Q: How do you access a value in a multidimensional array?

Answer 37

A: Use multiple indexes, e.g., $array[0][‘key’];.

Question 38

Q: How do you loop through a multidimensional array?

Answer 38

A: Use nested foreach loops.

Question 39

Q: What function recursively merges multidimensional arrays?

Answer 39

A: array_merge_recursive().

Question 40

Q: What function applies a callback recursively to an array?

Answer 40

A: array_walk_recursive().