Brave Search

How to convert a Roman numeral to integer in PHP?

stackoverflow.com › questions › 6265596 › how-to-convert-a-roman-numeral-to-integer-in-php

How about this:

$romans = array(
    'M' => 1000,
    'CM' => 900,
    'D' => 500,
    'CD' => 400,
    'C' => 100,
    'XC' => 90,
    'L' => 50,
    'XL' => 40,
    'X' => 10,
    'IX' => 9,
    'V' => 5,
    'IV' => 4,
    'I' => 1,
);

$roman = 'MMMCMXCIX';
$result = 0;

foreach ($romans as value) {
    while (strpos($roman, $key) === 0) {
        $result += $value;
        $roman = substr($roman, strlen($key));
    }
}
echo $result;

which should output 3999 for the supplied $roman. It seems to work for my limited testing:

MCMXC = 1990
MM = 2000
MMXI = 2011
MCMLXXV = 1975

You might want to do some validation first as well :-)

Answer from andyb on Stack Overflow

LeetCode

leetcode.com › problems › roman-to-integer

Roman to Integer - LeetCode

Roman to Integer - Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M. Symbol Value I 1 V 5 X 10 L 50 C 100 D 500 M 1000 For example, 2 is written as II in Roman numeral, just two ones added together.

GeeksforGeeks

geeksforgeeks.org › dsa › roman-number-to-integer

Roman to Integer Conversion - GeeksforGeeks

08:51

The idea for converting a Roman numeral to an integer is that, we have to traverse the string from left to right. For each symbol compare it with the next symbol (if it exists). If the current symbol is greater than or equal to the next symbol ...

Published: July 10, 2026

Discussions

Roman To Integer Difficulty

future stupendous many apparatus head elderly attraction wise desert shy This post was mass deleted and anonymized with Redact More on reddit.com

r/leetcode

November 18, 2022

How to convert a Roman numeral to integer in PHP? - Stack Overflow

Using PHP, I'd like to convert a string containing a Roman number into its integer representation. I need this because I need to make calculations on them. Wikipedia on Roman numerals It would su... More on stackoverflow.com

stackoverflow.com

[PROJECT] Roman Numeral -> Integer Converter

here is my_code in Python 2. detects incorrect inputs; please suggest any better approach!! Thanks

Top answer

1 of 4

future stupendous many apparatus head elderly attraction wise desert shy This post was mass deleted and anonymized with Redact

2 of 4

I work at a global tech company that isn't Faang but you would absolutely know. I generally interview for Senior and Principal level positions. I use this problem as my interview question. I love it. It tells me far more about you as a programmer than a leetcode medium or hard. All that I know when you pass a hard is that you studied for the test. I'm not looking for that kind of engineer. When I give this problem it is rare that I get an engineer who has seen it for precisely the comments made on this thread. Then, I get to see somebody work through a straightforward problem with a simple solution. I generally see 4 types of responses: Completely lost, quiet, stumped. Doesn't ask for help or really talk through the problem. These people don't present a solution. Mostly lost. They start trying to solve this like it's a leetcode hard. They often don't work with me as they think they're expected to pull a rabbit out of a hat. Somewhat lost but they see that there's a solution possible. They start work and talk to me about what they're doing. I can offer guidance and often they can solve the problem. Their code may not be beautiful or perfect, but they show me how they think. quick solve. They've seen the problem before or they see the solution quickly. (I've only had this happen once). They talk through the solution, write a beautiful piece of code which is well functionalized, clear, concise, and nearly perfect. 1 and 2 are failures. 4 is a pass, but I'm going to focus on a lot of the other parts of the interview as well as what the other interviewers on the loop say. I'm really looking for 3 because, in reality, that's the job. Most of the time I'm going to ask you to do something you aren't going to know how to do, you won't have studied, and there likely isn't some algorithm you can fall back on having seen before. Our day to day coding tasks rarely require the silly techniques that are the focus of leetcode. Instead they require communication, clarity of thought, and simple solutions to what appear to be complex problems. I try to test for those skills and leave the leetcode hards to our bar raiser.

CalculatorSoup

calculatorsoup.com › calculators › conversions › roman-numeral-converter.php

Roman Numeral Converter

Convert Roman numerals to numbers or convert numbers to Roman numerals. Find Roman numerals up to 3,999,999 using I, V, X, L, C, D and M.

Find elsewhere

Google Bing Mojeek

AlgoMonster

algo.monster › home › 13. roman to integer

13. Roman to Integer - In-Depth Explanation

The implementation uses a hash table combined with a clever traversal pattern to convert Roman numerals to integers.

takeuforward

takeuforward.org › data-structure › roman-numerals-to-integer

Roman Numerals to Integer - Tutorial

Search for a command to run

Wikipedia

en.wikipedia.org › wiki › Roman_numerals

Roman numerals - Wikipedia

7 hours ago - The use of Roman numerals has continued long after the decline of the Roman Empire. From the 14th century on, Roman numerals began to be replaced by the positional Hindu–Arabic numeral system; however, this process was gradual, and the use of Roman numerals has persisted in some contexts, ...

Description Origin Use in the Middle Ages and Renaissance Modern use Unicode Sources Further reading

Stack Overflow

stackoverflow.com › questions › 6265596 › how-to-convert-a-roman-numeral-to-integer-in-php

How to convert a Roman numeral to integer in PHP? - Stack Overflow

Top answer

1 of 14

How about this:

$romans = array(
    'M' => 1000,
    'CM' => 900,
    'D' => 500,
    'CD' => 400,
    'C' => 100,
    'XC' => 90,
    'L' => 50,
    'XL' => 40,
    'X' => 10,
    'IX' => 9,
    'V' => 5,
    'IV' => 4,
    'I' => 1,
);

$roman = 'MMMCMXCIX';
$result = 0;

foreach ($romans as value) {
    while (strpos($roman, $key) === 0) {
        $result += $value;
        $roman = substr($roman, strlen($key));
    }
}
echo $result;

which should output 3999 for the supplied $roman. It seems to work for my limited testing:

MCMXC = 1990
MM = 2000
MMXI = 2011
MCMLXXV = 1975

You might want to do some validation first as well :-)

2 of 14

I am not sure whether you've got ZF or not, but in case you (or any of you who's reading this) do here is my snippet:

$number = new Zend_Measure_Number('MCMLXXV', Zend_Measure_Number::ROMAN);
$number->convertTo (Zend_Measure_Number::DECIMAL);
echo $number->getValue();

Zend_Measure_Number on framework.zend.com

LeetCode

leetcode.com › problems › integer-to-roman

Integer to Roman - LeetCode

Can you solve this real interview question? Integer to Roman - Seven different symbols represent Roman numerals with the following values: Symbol Value I 1 V 5 X 10 L 50 C 100 D 500 M 1000 Roman numerals are formed by appending the conversions of decimal place values from highest to lowest.

Medium

medium.com › @soham-khade › 12-integer-to-roman-leetcode-problem-java-f51fb96b8159

12. Integer to Roman LeetCode Problem (Java) | by Soham | Medium

October 27, 2023 - For example, 2 is written as II in Roman numeral, just two one's added together. 12 is written as XII, which is simply X + II.

AlgoMonster

algo.monster › home › 12. integer to roman

12. Integer to Roman - In-Depth Explanation

The conversion follows a fixed greedy table from largest to smallest Roman value, so the solution is direct simulation of the subtraction rules.Open in Flowchart ... First, let's pin down the algorithm using the Flowchart. Here's a step-by-step walkthrough: ... No: The input is a single integer.

NeetCode

neetcode.io › solutions › 12. integer to roman

LeetCode 12 Integer to Roman Solution & Explanation | NeetCode

When building the Roman numeral string, you must process values from largest to smallest. Starting with smaller values or processing in random order will produce incorrect results. For example, processing 1994 by handling ones before thousands would give an invalid representation. When computing how many times a symbol should appear, some implementations confuse the division and modulo operations. You need integer division to get the count of symbols, then modulo to get the remaining value.

Medium

medium.com › @kollisnehagowri › title-solving-the-roman-to-integer-problem-from-leetcode-88a1dfe4869b

Solving the Roman to Integer Problem From LeetCode | by Sneha Gowri Kolli | Medium

September 8, 2023 - To convert a Roman numeral into an integer efficiently, we can iterate through the string from left to right and accumulate the values. We need to consider the special cases where a smaller numeral precedes a larger one, indicating subtraction ...

John Kavanagh

johnkavanagh.co.uk › home › articles › leetcode: converting integers to roman numerals

LeetCode: Converting Integers to Roman Numerals | John Kavanagh

January 8, 2024 - Traditional Roman numerals do not have a clean built‑in representation for zero, negative numbers, or very large values without extra notation. For a LeetCode‑style version of the problem, the useful range is usually 1 to 3999. That range decision belongs in the function contract. Either reject values outside it or document that the function expects valid positive integers in that range.

Medium

medium.com › @fanjum524 › leetcode-problem-no-13-44d63508428c

Leetcode Problem no.13. Roman to Integer | by Farhan | Medium

August 9, 2024 - 6. else: res += roman[s[i]]: If the condition is false, simply add the current character's value to the result. 7. return res: Returns the final calculated integer value.

Medium

medium.com › @ashwinmani37 › best-solution-for-integer-to-roman-numeral-c-code-ff7ef4f92470

Best Solution for Integer to Roman Numeral C++ Code | by Ashwin Mani | Medium

June 14, 2023 - We would start breaking the number by dividing it with the highest notation provided to us which is M i.e- 1000. If the number is divisible by 1000, we concat ‘M’ in our final string representing 1000 in Roman Numeral and deduct 1000 from the given number.

GitHub

github.com › doocs › leetcode › blob › main › solution › 0000-0099 › 0012.Integer to Roman › README_EN.md

leetcode/solution/0000-0099/0012.Integer to Roman/README_EN.md at main · doocs/leetcode

Converting a decimal place value into a Roman numeral has the following rules: If the value does not start with 4 or 9, select the symbol of the maximal value that can be subtracted from the input, append that symbol to the result, subtract its value, and convert the remainder to a Roman numeral.

Author: doocs