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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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