PHP Exercises: Check a flat list for duplicate values

Last update on May 27 2025 13:09:15 (UTC/GMT +8 hours)

84. Duplicate Value Checker in a Flat List

Write a PHP program to check a flat list for duplicate values. Returns true if duplicate values exists and false if values are all unique.

Sample Solution:

PHP Code:

<?php
// Function definition for 'has_Duplicates' that takes an array of items as a parameter
function has_Duplicates($items)
{
    // Check if the count of items is greater than the count of unique items
    if (count($items) > count(array_unique($items)))
        // If duplicates are found, return 1 (true)
        return 1;
    else
        // If no duplicates are found, return 0 (false)
        return 0;
}

// Call 'has_Duplicates' with an array containing duplicates and display the result using 'print_r'
print_r(has_Duplicates([1, 2, 3, 4, 5, 5])); 

// Display a newline
echo "\n";

// Call 'has_Duplicates' with an array without duplicates and display the result using 'print_r'
print_r(has_Duplicates([1, 2, 3, 4, 5])); 

?>

Explanation:

Function Definition:

The function has_Duplicates takes a single parameter, $items, which is expected to be an array.

Count Comparison:

The function checks if the total count of items in the array (count($items)) is greater than the count of unique items in the array (count(array_unique($items))).

Return Value:

If the count of items is greater than the count of unique items:

The function returns 1 (indicating that duplicates are present).

If the count of items is equal to the count of unique items:

The function returns 0 (indicating that no duplicates are present).

Example Usage with Duplicates:

The function is called with an array containing duplicates: [1, 2, 3, 4, 5, 5].
The result (1) is displayed using print_r, indicating that duplicates are found.

Example Usage without Duplicates:

The function is called with an array without duplicates: [1, 2, 3, 4, 5].
The result (0) is displayed using print_r, indicating that no duplicates are found.

Purpose:

The has_Duplicates function provides a simple way to check for duplicate values in an array and returns a boolean-like result (1 for true, 0 for false) based on the presence of duplicates.

Output:

1
0

Flowchart:

For more Practice: Solve these Related Problems:

Write a PHP script to determine if a flat array contains any duplicate values without using built-in uniqueness functions.
Write a PHP function to scan an array and return true if duplicate elements are found.
Write a PHP script to compare array length with the count of unique values and output a boolean for duplication.
Write a PHP script to iterate through a list and flag if any value appears more than once.

Go to:

PREV : Group Array Elements by Callback Result.
NEXT : Retrieve the Head of a List.

PHP Code Editor:

Have another way to solve this solution? Contribute your code (and comments) through Disqus.