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c# -find roman numerals and convert to int

Posted on 2010-11-24
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Last Modified: 2013-12-17
hello everybody.. im in a bit of problem now..

i need to find roman numerals in a string and convert it to int eg:

"XIV VARA CIVIL" = int 14
"VARA CIVIL XX" = int 20

does anyone know if there is any method for it in web? maybe a regex to find could work but i have no clue or time to make such conversor

thx for the help!

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Question by:eguilherme
5 Comments
 
LVL 32

Expert Comment

by:Erick37
ID: 34208281
Will the numerals always be at either the beginning or end of the string?
Will "VARA CIVIL" always be in the string?
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LVL 10

Author Comment

by:eguilherme
ID: 34208317
not really.. that was just a sample..

the roman numerals could be anywhere in the string (most of the time they are at either the beggining or at the end, but i cant be sure if that would be always the case)

but the text it will be different everytime.

is it possible to do such thing ?
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LVL 6

Expert Comment

by:ajb2222
ID: 34208470
Since the roman numeral will always be a word, first break the string into it's component words.

         string y = "VARA CIVIL XX";
         string[] x = y.Split(' ');

this makes anarray of strings
     x[0] = "VERA"
     x[1] = "CIVIL"
     x[2] = "XX"

then try each value in the string array x to see if it is a valid roman numeral.

Here is a link to an example of how to convert a roman numeral to a number.
http://www.blackwasp.co.uk/RomanToNumber.aspx
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LVL 35

Expert Comment

by:Terry Woods
ID: 34208800
You could do a regex match with pattern:
(?i)\b(?=[ivxlcdm]+)M{0,4}(?:CM|CD|D?C{0,3})(?:XC|XL|L?X{0,3})(?:IX|IV|V?I{0,3})\b

Based on, but slightly modified from, a pattern from: http://stackoverflow.com/questions/267399/how-do-you-match-only-valid-roman-numerals-with-a-regular-expression

That would capture only valid roman numerals, I believe - then you'd have to convert them to an integer.
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LVL 12

Accepted Solution

by:
jmcmunn earned 500 total points
ID: 34247659
Once you have just the valid roman numerals, here is some javascript that converts both to and from roman numerals.  It is trivial to switch this to C# or whatever you want.
<script language="javascript">



<!--



function Level(i, v, x)

        {

        this.i = i;

        this.v = v;

        this.x = x

        }



levels = new Array();



levels[0] = new Level('I', 'V', 'X');

levels[1] = new Level('X', 'L', 'C');

levels[2] = new Level('C', 'D', 'M');









function calcDigit(d, l)

        {

        if (l > 2)

                {

                str = '';

                for (var m = 1; m <= d * Math.pow(10, l - 3) ; m++)

                        str += 'M';

                return str

                }

                        

        else

                if (d == 1)

                        return levels[l].i

                else

                        if (d == 2)

                                return levels[l].i + levels[l].i

                        else

                                if (d == 3)

                                        return levels[l].i + levels[l].i + levels[l].i

                                else

                                        if (d == 4)

                                                return levels[l].i + levels[l].v

                                        else

                                                if (d == 5)

                                                        return levels[l].v

                                                else

                                                        if (d == 6)

                                                                return levels[l].v + levels[l].i

                                                        else

                                                                if (d == 7)

                                                                        return levels[l].v + levels[l].i + levels[l].i

                                                                else

                                                                        if (d == 8)

                                                                                return levels[l].v + levels[l].i + levels[l].i + levels[l].i

                                                                        else

                                                                                if (d == 9)

                                                                                        return levels[l].i + levels[l].x

                                                                                else

                                                                                        return ''

        }



function toRoman(n)

        {

        var r = ''

        for (var c = 0; c < n.length; c++)

                r += calcDigit(eval(n.charAt(c)), n.length - c - 1);

        return r        

        }

        

function fromRoman(n)

        {

        var r = 0

        

        for (var c = 0; c < n.length; c++)

                {

                var chr = n.charAt(c).toLowerCase();

                if (c < n.length - 1)

                        var next = n.charAt(c + 1).toLowerCase()

                else

                        var next = '';

                        

                if (c > 0)

                        var prev = n.charAt(c - 1).toLowerCase()

                else

                        var prev = '';

                

                if (chr == 'i')

                        {

                        if (next == 'v')

                                r += 4

                        else

                                if (next == 'x')

                                        r += 9

                                else

                                        r += 1;

                        continue

                        }

                        

                if (chr == 'v') 

                        {

                        if (prev != 'i')

                                r += 5;

                        continue

                        }

                        

                if (chr == 'x')

                        {

                        if (prev != 'i')

                                if (next == 'l')

                                        r += 40

                                else

                                        if (next == 'c')

                                                r += 90

                                        else

                                                r += 10;

                        continue

                        }

                        

                if (chr == 'l')

                        {

                        if (prev != 'x')

                                r += 50;

                        continue

                        }

                        

                if (chr == 'c')

                        {

                        if (prev != 'x')

                                if (next == 'd')

                                        r += 400

                                else

                                        if (next == 'm')

                                                r += 900

                                        else

                                                r += 100;

                        continue

                        }



                if (chr == 'd')

                        {

                        if (prev != 'c')

                                r += 500;

                        continue

                        }

                

                if (chr == 'm')

                        {

                        if (prev != 'c')

                                r += 1000;

                        continue

                                

                        }

                }

        

        return r

        

        }





function isNuneric(str)

        {

        for (var c = 0; c < str.length; c++)

                {

                var chr = str.charAt(c);

                if (chr != '0' & chr != '1' & chr != '2' & chr != '3' & chr != '4' & chr != '5' & chr != '6' & chr != '7' & chr != '8' & chr != '9')

                        return false

                }

        return true

        }



function get(f)

        {

        

        var n = f.elements[0].value

        

        if (!isNuneric(n))

                {

                for (var c = 0; c < n.length; c++)

                        {

                        var chr = n.charAt(c).toLowerCase();

                        if (chr != 'i' & chr != 'v' & chr != 'x' & chr != 'l' & chr != 'c' & chr != 'd' & chr != 'm')

                                {

                                alert ('Only the letters IVXLCDM, please');

                                return false

                                }

                        }

                mode = 'fromRoman'

                }

        else

                mode = 'toRoman';



        if (mode == 'toRoman')

                f.elements[0].value = toRoman(f.elements[0].value)

        else

                f.elements[0].value = fromRoman(f.elements[0].value);

        

        return false

        }

  

function go(site)

        {

        if (site.selectedIndex>0)

                top.location=site.options[site.selectedIndex].value

        }





function foc()

        {

        if (navigator.userAgent.indexOf('Mozilla/3') != -1 | navigator.userAgent.indexOf('Mozilla/4') != -1)

                document.forms[0].elements[0].focus()   

        }



//-->



</script>

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