PHP Math Exercises: Convert Arabic numbers to Roman numerals

Last update on June 02 2025 13:00:28 (UTC/GMT +8 hours)

9. Arabic to Roman Numerals Conversion

Write a PHP function to convert Arabic numbers to Roman numerals.

Visual Presentation:

$PHP Math Exercises: Convert Arabic numbers to Roman numerals$

Sample Solution:

PHP Code:

<?php
function arabic_rome($num)
{
    $c = 'IVXLCDM'; // Roman numeral characters
    for ($x = 5, $y = $result = ''; $num; $y++, $x ^= 7) { // Loop until $num is not zero
        $o = $num % $x; // Remainder of $num divided by $x
        $num = $num / $x ^ 0; // Integer division of $num by $x
        // Loop to append the corresponding Roman numeral characters to $result
        for (; $o--; $result = $c[$o > 2 ? $y + $num - ($num = -2) + $o = 1 : $y] . $result);
    }
    return $result; // Return the Roman numeral representation of the input number
}
print_r(arabic_rome(101) . "\n"); // Test the function with input 101
?>

Output:

CI

Explanation:

In the exercise above,

function arabic_rome($num) {: This line defines a function named "arabic_rome()" that takes an Arabic numeral '$num' as input.
$c = 'IVXLCDM';: This line defines a string '$c' containing Roman numeral characters from 1 to 1000 (I, V, X, L, C, D, M).
for ($x = 5, $y = $result = ''; $num; $y++, $x ^= 7) {: This line initializes variables '$x', '$y', and '$result'. It then enters a loop that continues until '$num' becomes zero. During each iteration, '$y' is incremented and '$x' is bitwise XORed with 7 (alternating between 2 and 5).
$o = $num % $x;: This line calculates the remainder of '$num' divided by '$x' and stores it in '$o'.
$num = $num / $x ^ 0;: This line performs integer division of '$num' by '$x' and updates '$num' with the quotient.
The subsequent "for" loop iterates '$o' times and appends the corresponding Roman numeral characters to '$result' based on the value of '$o' and '$y'.
return $result;: This line returns the final Roman numeral representation of the input number.
The "print_r" statement tests the "arabic_rome()" function with the input number 101 and prints the result.

Flowchart :

$Flowchart: Convert Arabic numbers to Roman numerals$

For more Practice: Solve these Related Problems:

Write a PHP function to convert an integer to a Roman numeral by mapping values and subtracting iteratively.
Write a PHP script to take an array of Arabic numbers and return an array of their Roman numeral equivalents.
Write a PHP program to validate the conversion function by comparing its output with known Roman numeral values.
Write a PHP function to handle edge cases like zero and negative numbers while converting to Roman numerals.

Go to:

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PHP Code Editor:

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