[Tutor] Roman to digital (pseudocode)
kent37 at tds.net
Wed Mar 14 00:51:40 CET 2007
Alan Gilfoy wrote:
> This, I heard, is more difficult than digital-to-Roman, since you have
> to "read" the subtractive cases, with a smaller numeral placed before
> a larger numeral, without simply adding all the numerals' values up
> I'm going to use a raw_input prompt to ask the user which Roman
> numeral he/she wants to convert. How do I "screen" for inputs that
> have characters besides "I", "V", "X", "L", "C", "D", or "M"?
You could have a string containing all the allowed characters and make
sure each input character is in the allowed list.
> Second Python question:
> I know there's a way to "find out" the name of the first item in a list
> (ListName), but is there a way to find out the first character of a string?
Lists and strings are both sequences and many of the same operations
work on both. (All of the immutable sequence operations work on both.)
So MyString is the first character in a string.
> Also, is there a way to "ask" Python what characters are before and
> after the character in the string that you're asking about?
> For example, usign the sample string "MCMXVII" (1917):
> How would you ask Python:
> "What's the 3rd character in this string?" (returns "M")
> "What's before that character?" (returns "C")
s or maybe s[2-1] if the 2 is actually in a variable.
More information about the Tutor