PHP Array Exercises : Remove duplicate values from an array which contains only integers or strings

Last update on May 30 2025 13:13:46 (UTC/GMT +8 hours)

39. Remove Duplicate Values from Array

Write a PHP program to remove duplicate values from an array which contains only strings or only integers.

Sample Solution:

PHP Code:

<?php
// Define an array of colors
$colors = array( 
    0 => 'Red', 
    1 => 'Green', 
    2 => 'White', 
    3 => 'Black', 
    4 => 'Red', 
); 

// Define an array of numbers
$numbers = array( 
    0 => 100, 
    1 => 200, 
    2 => 100, 
    3 => -10, 
    4 => -10, 
    5 => 0, 
);

// Use array_flip to swap keys and values, then use array_keys to extract unique values
$uniq_colors = array_keys(array_flip($colors)); 

// Use array_flip to swap keys and values, then use array_keys to extract unique values
$uniq_numbers = array_keys(array_flip($numbers)); 

// Display the array of unique colors
print_r($uniq_colors);

// Display the array of unique numbers
print_r($uniq_numbers);

?>

Output:

Array                                                       
(                                                           
    [0] => Red                                              
    [1] => Green                                            
    [2] => White                                            
    [3] => Black                                            
)                                                           
Array                                                       
(                                                           
    [0] => 100                                              
    [1] => 200                                              
    [2] => -10                                              
    [3] => 0                                                
)

Flowchart:

For more Practice: Solve these Related Problems:

Write a PHP script to remove duplicate strings from an array without using array_unique(), using a manual iteration approach.
Write a PHP function to eliminate duplicate integers from an array and then sort the resulting unique values.
Write a PHP program to compare two arrays and output the difference as a new array containing unique values only.
Write a PHP script to implement duplicate removal from an array of strings using a custom algorithm that preserves original order.

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