Array sort functions in PHP - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to sort the array in ascending order.

PHP

<?php
$numbers = [4, 2, 8, 6];
[1]($numbers);
print_r($numbers);
?>

Drag options to blanks, or click blank then click option'

Arsort

Bsort

Casort

Dksort

Attempts:

3 left

💡 Hint

Common Mistakes

Using rsort which sorts in descending order.

Using ksort which sorts by keys, not values.

The sort function sorts the array in ascending order by values and reindexes the keys.

2fill in blank

medium

Complete the code to sort the array in descending order.

PHP

<?php
$letters = ['a', 'd', 'b', 'c'];
[1]($letters);
print_r($letters);
?>

Drag options to blanks, or click blank then click option'

Arsort

Bsort

Casort

Dksort

Attempts:

3 left

💡 Hint

Common Mistakes

Using sort which sorts in ascending order.

Using ksort which sorts by keys.

The rsort function sorts the array in descending order by values and reindexes the keys.

3fill in blank

hard

Fix the error in the code to sort the array by keys in ascending order.

PHP

<?php
$ages = ['John' => 25, 'Jane' => 22, 'Doe' => 30];
[1]($ages);
print_r($ages);
?>

Drag options to blanks, or click blank then click option'

Aksort

Brsort

Csort

Dasort

Attempts:

3 left

💡 Hint

Common Mistakes

Using sort or asort which sort by values.

Using rsort which sorts in descending order.

The ksort function sorts the array by keys in ascending order.

4fill in blank

hard

Fill both blanks to sort the array by values in ascending order while preserving keys.

PHP

<?php
$scores = ['Alice' => 85, 'Bob' => 92, 'Charlie' => 78];
[1]($scores);
print_r($scores);
?>

Drag options to blanks, or click blank then click option'

Aarsort

Bksort

Casort

Drsort

Attempts:

3 left

💡 Hint

Common Mistakes

Using sort which reindexes keys.

Using ksort which sorts by keys.

The asort function sorts the array by values in ascending order and preserves the keys.

5fill in blank

hard

Fill all three blanks to sort the array by values in descending order while preserving keys.

PHP

<?php
$grades = ['Math' => 90, 'Science' => 85, 'English' => 88];
[1]($grades);
print_r($grades);
?>

Drag options to blanks, or click blank then click option'

Aasort

Brsort

Cksort

Darsort

Attempts:

3 left

💡 Hint

Common Mistakes

Using rsort which does not preserve keys.

Using ksort which sorts by keys.

The arsort function sorts the array by values in descending order and preserves the keys.

Practice

1. Which PHP function sorts an array and keeps the original keys intact?

easy

A. rsort()

B. sort()

C. ksort()

D. asort()

Solution

1. Step 1: Understand key preservation in sorting

   asort() sorts values but keeps the original keys unchanged.

2. Step 2: Compare with other functions

   sort() resets keys, rsort() sorts in reverse but resets keys, ksort() sorts by keys, not values.

3. Final Answer:

   asort() -> Option D

4. Quick Check:

   Keep keys while sorting values = asort() [OK]

Hint: Use asort() to sort values and keep keys unchanged [OK]

Common Mistakes:

• Confusing sort() with asort() for key preservation
• Thinking ksort() sorts by values
• Assuming rsort() keeps keys

2. Which of the following is the correct syntax to sort an array in ascending order and reset keys in PHP?

easy

A. asort($array);

B. sort($array);

C. ksort($array);

D. arsort($array);

Solution

1. Step 1: Identify function for ascending sort with key reset

   sort() sorts array values in ascending order and resets keys.

2. Step 2: Check other options

   asort() keeps keys, ksort() sorts by keys, arsort() sorts descending.

3. Final Answer:

   sort($array); -> Option B

4. Quick Check:

   Ascending sort with reset keys = sort() [OK]

Hint: Use sort() to sort ascending and reset keys [OK]

Common Mistakes:

• Using asort() when keys should reset
• Confusing ksort() with value sort
• Using arsort() for ascending order

3. What will be the output of the following PHP code?

$arr = [3 => 'apple', 1 => 'banana', 2 => 'cherry'];
sort($arr);
print_r($arr);

medium

A. [0 => 'apple', 1 => 'banana', 2 => 'cherry']

B. [1 => 'banana', 2 => 'cherry', 3 => 'apple']

C. [0 => 'banana', 1 => 'cherry', 2 => 'apple']

D. [0 => 'apple', 1 => 'cherry', 2 => 'banana']

Solution

1. Step 1: Understand sort() behavior on keys

   sort() sorts values ascending and resets keys starting from 0.

2. Step 2: Sort values and assign new keys

   Values sorted ascending: 'apple', 'banana', 'cherry'. Keys reset to 0,1,2 respectively.

3. Final Answer:

   [0 => 'apple', 1 => 'banana', 2 => 'cherry'] -> Option A

4. Quick Check:

   sort() resets keys and sorts ascending [OK]

Hint: sort() resets keys and sorts values ascending [OK]

Common Mistakes:

• Expecting original keys to remain
• Confusing sort() with asort()
• Mixing order of sorted values

4. Identify the error in the following PHP code snippet:

$arr = ['b' => 2, 'a' => 1, 'c' => 3];
ksort($arr, SORT_DESC);
print_r($arr);

medium

A. ksort() sorts values, not keys

B. Array keys must be numeric for ksort()

C. ksort() does not accept SORT_DESC as a parameter

D. print_r() cannot print associative arrays

Solution

1. Step 1: Check ksort() parameters

   ksort() sorts array by keys in ascending order only; it does not support descending order.

2. Step 2: Understand SORT_DESC usage

   SORT_DESC is invalid for ksort(); to sort keys descending, use krsort() instead.

3. Final Answer:

   ksort() does not accept SORT_DESC as a parameter -> Option C

4. Quick Check:

   ksort() only sorts keys ascending [OK]

Hint: Use krsort() for descending key sort, not ksort() [OK]

Common Mistakes:

• Passing SORT_DESC to ksort()
• Thinking ksort() sorts values
• Believing print_r() can't print associative arrays

5. You have an associative array with user IDs as keys and scores as values:

$scores = [101 => 50, 102 => 75, 103 => 50, 104 => 90];

You want to sort the array by scores in descending order but keep the user IDs as keys. Which function should you use?

hard

A. arsort()

B. rsort()

C. krsort()

D. sort()

Solution

1. Step 1: Identify sorting by values descending with keys preserved

   arsort() sorts array by values in descending order and keeps keys intact.

2. Step 2: Compare with other functions

   rsort() sorts values descending but resets keys, krsort() sorts keys descending, sort() sorts ascending and resets keys.

3. Final Answer:

   arsort() -> Option A

4. Quick Check:

   Sort values descending and keep keys = arsort() [OK]

Hint: Use arsort() to sort values descending and keep keys [OK]

Common Mistakes:

• Using rsort() which resets keys
• Confusing krsort() with value sort
• Using sort() which sorts ascending and resets keys