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From: monta@cmu-cs-g.ARPA (Peter Monta)
Newsgroups: net.sources
Subject: rtoi---``roman to integer''
Message-ID: <267@cmu-cs-g.ARPA>
Date: Sun, 28-Apr-85 11:45:11 EDT
Article-I.D.: cmu-cs-g.267
Posted: Sun Apr 28 11:45:11 1985
Date-Received: Mon, 29-Apr-85 06:31:46 EDT
Organization: Carnegie-Mellon University, CS/RI
Lines: 37

Here is a C function that converts roman numeral strings to integers.  It
doesn't complain about syntax errors (I seem to remember my junior-high-school
teacher insisting that ``IC'' is wrong, should be ``XCIX''; something like
only one ``level'' of subtractive notation permitted).  Anyway, if these
semantics are wrong, tell me about it.  (Thank goodness for positional
notation.)

Peter Monta
monta@cmu-cs-g
..!rocherster!cmu-cs-pt!cmu-cs-g!monta

-----------------------------------Cut Here-----------------------------------
#include <stdio.h>

#define max_table 7
static struct { char name; int value } table[max_table] =
  { {'i',1}, {'v',5}, {'x',10}, {'l',50}, {'c',100}, {'d',500}, {'m',1000} };

int rtoi(s)
char s[];
{ int i,j,old,new,sum;
  sum = 0;  old = 0;
  for (i=strlen(s)-1; i>=0; i--)
    for (j=0; j<max_table; j++)
      if (table[j].name==s[i]) {
        new = table[j].value;
        if (new < old) sum -= new; else sum += new;
        old = new;
        break; }
  return sum; }

main()
{ char s[50];
  for (;;) {
    printf("roman numeral: ");
    scanf("%s",s);
    printf("value is %d\n",rtoi(s)); } }