# how to make a function that convert roman number to arabic number

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Muhammad Usman Saleem on 2 Jun 2015
Commented: Walter Roberson on 17 Aug 2015
Hi everyone;
I am going to attempt that question:
"function called roman that takes a string representing an integer between 1 and 20 inclusive using Roman numerals and returns the Arabic equivalent as a number of type uint8. If the input is illegal or its value is larger than 20, roman returns 0 instead. The rules for Roman numerals can be found here: http://en.wikipedia.org/wiki/Roman_numerals. Use the definition at the beginning of the page under the “Reading Roman Numerals” heading. In order to have unambiguous one-to-one mapping from roman to Arabic numbers, consider only the shortest possible roman representation as legal. Therefore, only three consecutive symbols can be the same (IIII or VIIII are illegal, but IV and IX are fine), and a subtractive notation cannot be followed by an additive one using the same symbols making strange combinations, such as IXI for 10 or IXX for 19, illegal also."
i am using that code:
function myarabic=roman(n)
switch n
case 'I'
myarabic=1;
case 'II'
myarabic=2;
case 'III'
myarabic=3;
case 'IV'
myarabic=4;
case 'V'
myarabic=5;
case 'VI'
myarabic=6;
case 'VII'
myarabic=7;
case 'VIII'
myarabic=8;
case 'IX'
myarabic=9;
case 'X'
myarabic=10;
case 'XI'
myarabic=11;
case 'XII'
myarabic=12;
case 'XIII'
myarabic=13;
case 'XIV'
myarabic=14;
case 'XV'
myarabic=15;
case 'XVI'
myarabic=16;
case 'XVII'
myarabic=17;
case 'XVIII'
myarabic=18;
case 'XIX'
myarabic=19;
case 'XX'
myarabic=20;
otherwise
myarabic=0;
end
end
but when i test this code i got an error :
Muhammad Usman Saleem on 2 Jun 2015

Muhammad Usman Saleem on 2 Jun 2015
I find the error : we have to return uint8 arabic number in output..
Walter Roberson on 9 Jun 2015
The code there does not return the numbers as uint8() numbers, and the code there does not return uint8(0) for invalid strings.

Ingrid on 2 Jun 2015
how do you test your code?
When I do
roman('I')
ans =
1
or
roman('XX')
ans =
20
the answer is as expected so it is not really clear what your problem is?
Muhammad Usman Saleem on 2 Jun 2015
@ Ingrid thanks for contributions.. Actually i have grader which will run and test whether my program makes sense or not? I have posted complete question above. Please read this and check whether i am doing correct or not?

Tai Kieu on 16 Aug 2015
Can you explain more about making the ouput uint8? I don't really quite understand about it.
Walter Roberson on 17 Aug 2015
double_7 = 7.0;
uint8_7 = uint8(double_7);