Array search functions in PHP - Mini Project: Build & Apply

Array search functions

📖 Scenario: You are working on a small PHP program to find specific values inside an array of fruits. This is like looking for your favorite fruit in a fruit basket.

🎯 Goal: You will create an array of fruits, set a fruit to search for, use PHP array search functions to find if the fruit is in the basket, and then print the result.

📋 What You'll Learn

Create an array called $fruits with the exact values: 'apple', 'banana', 'cherry', 'date', 'elderberry'

Create a variable called $searchFruit and set it to 'cherry'

Use the PHP function in_array() with $searchFruit and $fruits to check if the fruit is in the array

Print "Found cherry in the basket!" if the fruit is found, otherwise print "cherry is not in the basket."

💡 Why This Matters

🌍 Real World

Searching arrays is common when you want to check if an item exists in a list, like checking if a username is taken or if a product is in stock.

💼 Career

Knowing how to search arrays is a basic skill for PHP developers working on websites, data processing, or any application that handles lists of data.

1

Create the fruits array

Create an array called $fruits with these exact values: 'apple', 'banana', 'cherry', 'date', 'elderberry'.

PHP

<?php

// Create the array $fruits with the given fruits

Hint

Use square brackets [] to create the array and separate values with commas.

2

Set the fruit to search

Create a variable called $searchFruit and set it to the string 'cherry'.

PHP

<?php
$fruits = ['apple', 'banana', 'cherry', 'date', 'elderberry'];

// Set $searchFruit to 'cherry'

Hint

Use the assignment operator = to set the variable.

3

Check if the fruit is in the array

Use the PHP function in_array() with $searchFruit and $fruits to check if the fruit is in the array. Store the result in a variable called $found.

PHP

<?php
$fruits = ['apple', 'banana', 'cherry', 'date', 'elderberry'];
$searchFruit = 'cherry';

// Use in_array() to check if $searchFruit is in $fruits and store in $found

Hint

The function in_array() returns true if the value is found, otherwise false.

4

Print the search result

Write an if statement to print "Found cherry in the basket!" if $found is true, otherwise print "cherry is not in the basket.".

PHP

<?php
$fruits = ['apple', 'banana', 'cherry', 'date', 'elderberry'];
$searchFruit = 'cherry';
$found = in_array($searchFruit, $fruits);

// Print the result using if statement

Hint

Use if ($found) to check the boolean and print() to show the message.

Practice

1. Which PHP function returns the key of a value in an array if found, or false if not found?

easy

A. in_array

B. array_search

C. array_key_exists

D. array_keys

Solution

1. Step 1: Understand function purpose

   array_search looks for a value and returns its key if found.

2. Step 2: Compare with other functions

   in_array returns true/false, not key; array_key_exists checks keys; array_keys returns all keys.

3. Final Answer:

   array_search -> Option B

4. Quick Check:

   Key returned by array_search = array_search [OK]

Hint: array_search returns key, in_array returns true/false [OK]

Common Mistakes:

• Confusing array_search with in_array
• Thinking array_key_exists returns value
• Assuming array_keys searches values

2. Which of the following is the correct syntax to check if the value 5 exists in array $arr using in_array?

easy

A. in_array(5, $arr);

B. in_array($arr, 5);

C. in_array($arr => 5);

D. in_array(5 => $arr);

Solution

1. Step 1: Recall in_array syntax

   The correct syntax is in_array(value, array).

2. Step 2: Match syntax with options

   in_array(5, $arr); matches in_array(5, $arr); which is correct.

3. Final Answer:

   in_array(5, $arr); -> Option A

4. Quick Check:

   in_array(value, array) = in_array(5, $arr) [OK]

Hint: Remember in_array(value, array) order [OK]

Common Mistakes:

• Swapping parameters order
• Using arrow syntax instead of comma
• Passing array as first argument

3. What is the output of the following PHP code?

$arr = ['apple', 'banana', 'cherry'];
$key = array_search('banana', $arr);
echo $key;

medium

A. 0

B. banana

C. false

D. 1

Solution

1. Step 1: Understand array_search behavior

   It returns the key of the searched value if found.

2. Step 2: Check array keys and searched value

   Array keys are 0=>'apple', 1=>'banana', 2=>'cherry'. Searching 'banana' returns key 1.

3. Final Answer:

   1 -> Option D

4. Quick Check:

   array_search('banana', $arr) = 1 [OK]

Hint: array_search returns index/key of found value [OK]

Common Mistakes:

• Expecting value instead of key
• Confusing false with 0
• Assuming it returns boolean

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

$arr = ['x' => 10, 'y' => 20];
if (array_search(30, $arr)) {
    echo 'Found';
} else {
    echo 'Not Found';
}

medium

A. array_search returns false but condition treats 0 as false

B. array_search returns key but 30 is not in array, so condition fails correctly

C. array_search should be replaced with in_array for this check

D. No error, code works as expected

Solution

1. Step 1: Analyze array_search return and condition

   array_search returns key or false. If key is 0, condition fails because 0 is falsey.

2. Step 2: Check searched value presence

   30 is not in array, so array_search returns false, condition is false, prints 'Not Found'. But if value was at key 0, condition would fail incorrectly.

3. Step 3: Suggest correct function for boolean check

   Use in_array which returns true/false directly for presence check.

4. Final Answer:

   array_search should be replaced with in_array for this check -> Option C

5. Quick Check:

   Use in_array for boolean presence check [OK]

Hint: Use in_array for true/false presence checks [OK]

Common Mistakes:

• Using array_search in if without strict check
• Ignoring 0 key treated as false
• Not using === to check false

5. Given the array $data = ['a' => 0, 'b' => false, 'c' => null, 'd' => '0'];, which function call correctly checks if the value 0 exists in the array considering type?

hard

A. in_array(0, $data, true);

B. array_search(0, $data);

C. in_array(0, $data);

D. array_search('0', $data, true);

Solution

1. Step 1: Understand strict checking

   Using third parameter true enforces type checking in in_array and array_search.

2. Step 2: Analyze array values and types

   Values are 0 (int), false (bool), null, and '0' (string). Only strict check distinguishes 0 (int) from others.

3. Step 3: Choose correct function and parameters

   in_array(0, $data, true) returns true only if exact int 0 found. array_search without strict may confuse types.

4. Final Answer:

   in_array(0, $data, true); -> Option A

5. Quick Check:

   Use in_array with strict=true for exact type match [OK]

Hint: Use in_array with strict=true to check exact value and type [OK]

Common Mistakes:

• Ignoring strict parameter causing false positives
• Using array_search without strict for type-sensitive check
• Confusing '0' string with 0 integer