Objective number C in Roman numerals

Question

I was always looking for some example code to convert from a number to Roman numerals in object c. Does anyone know where I can find a good example?

Update:

Nevermind, found a PHP function that does what I want, and ported it. Everything seems to be working fine so far.

-(NSString*)numberToRomanNumerals:(int)num{ if (num < 0 || num > 9999) { return @""; } // out of range NSArray *r_ones = [[NSArray alloc]initWithObjects:@"I", @"II", @"III", @"IV", @"V", @"VI", @"VII", @"VIII",@"IX",nil]; NSArray *r_tens = [[NSArray alloc]initWithObjects:@"X", @"XX", @"XXX", @"XL", @"L", @"LX", @"LXX",@"LXXX", @"XC",nil]; NSArray *r_hund = [[NSArray alloc]initWithObjects:@"C", @"CC", @"CCC", @"CD", @"D", @"DC", @"DCC",@"DCCC", @"CM",nil]; NSArray *r_thou = [[NSArray alloc]initWithObjects:@"M", @"MM", @"MMM", @"MMMM", @"MMMMM", @"MMMMMM",@"MMMMMMM", @"MMMMMMMM", @"MMMMMMMMM",nil]; int ones = num % 10; int tens = (num - ones) % 100; int hundreds = (num - tens - ones) % 1000; int thou = (num - hundreds - tens - ones) % 10000; tens = tens / 10; hundreds = hundreds / 100; thou = thou / 1000; NSString * rnum=@ ""; if (thou) { rnum = [rnum stringByAppendingString:[r_thou objectAtIndex:thou-1]]; } if (hundreds) { rnum = [rnum stringByAppendingString:[r_hund objectAtIndex:hundreds-1]]; } if (tens) { rnum = [rnum stringByAppendingString:[r_tens objectAtIndex:tens-1]]; } if (ones) { rnum = [rnum stringByAppendingString:[r_ones objectAtIndex:ones-1]]; } [r_ones release]; [r_tens release]; [r_hund release]; [r_thou release]; return rnum; } 

Answer 1

I think this is homework?

The conversion algorithm is just a simple iteration of "reduce the number, build a string", and you only need basic mathematical, comparative and string operations.

Go to Computer Algorithms , where you will find various algorithms discussed and presented in VB - it is easy to understand VB, even if you do not know the language.

Answer 2

A bit shorter and optimized based on the first algorithm

 +(NSString*)romain:(int)num { if (num < 0 || num > 9999) { return @""; } // out of range NSArray *r_ones = [NSArray arrayWithObjects:@"I", @"II", @"III", @"IV", @"V", @"VI", @"VII", @"VIII", @"IX", nil]; NSArray *r_tens = [NSArray arrayWithObjects:@"X", @"XX", @"XXX", @"XL", @"L", @"LX", @"LXX",@"LXXX", @"XC", nil]; NSArray *r_hund = [NSArray arrayWithObjects:@"C", @"CC", @"CCC", @"CD", @"D", @"DC", @"DCC",@"DCCC", @"CM", nil]; NSArray *r_thou = [NSArray arrayWithObjects:@"M", @"MM", @"MMM", @"MMMM", @"MMMMM", @"MMMMMM", @"MMMMMMM", @"MMMMMMMM", @"MMMMMMMMM", nil]; // real romans should have an horizontal __ ___ _____ // bar over number to make x 1000: 4000 is IV, 16000 is XVI, 32767 is XXXMMDCCLXVII... int thou = num / 1000; int hundreds = (num -= thou*1000) / 100; int tens = (num -= hundreds*100) / 10; int ones = num % 10; // cheap %, 'cause num is < 100! return [NSString stringWithFormat:@"%@%@%@%@", thou ? [r_thou objectAtIndex:thou-1] : @"", hundreds ? [r_hund objectAtIndex:hundreds-1] : @"", tens ? [r_tens objectAtIndex:tens-1] : @"", ones ? [r_ones objectAtIndex:ones-1] : @""]; } 

Answer 3

Here is the formatting implementation I created. It iterates over the list of various possible numbers, so it is very easy to modify it. It will convert an integer to a string right now, but I will update this if I implement the opposite direction.

 static unsigned majorIntValues[] = {1000,100,10,1,0}; #define numMajorIntValues (sizeof(majorIntValues) / sizeof(unsigned)) static char majorCharValues[] = {'M','C','X','I','N'}; #define numMajorCharValues (sizeof(majorCharValues) / sizeof(char)) static unsigned intValues[] = {1000,500,100,50,10,5,1}; #define numIntValues (sizeof(intValues) / sizeof(unsigned)) static char charValues[] = {'M','D','C','L','X','V','I'}; #define numCharValues (sizeof(charValues) / sizeof(char)) @implementation RomanNumeralFormatter - (NSString *)stringForObjectValue:(id)number { if(![number respondsToSelector:@selector(unsignedIntegerValue)]) return @"0"; NSUInteger value = [number unsignedIntegerValue]; if(value == 0) return @"N"; NSMutableString *string = [NSMutableString new]; uint8_t i,j; for(i = 0, j = 0; value && i < numIntValues; ++i) { while(intValues[i] <= majorIntValues[j]) ++j; while(value >= intValues[i]) { [string appendFormat:@"%c",charValues[i]]; value -= intValues[i]; } if(value >= (intValues[i] - majorIntValues[j])) { [string appendFormat:@"%c%c",majorCharValues[j],charValues[i]]; value -= (intValues[i] - majorIntValues[j]); } } return [string autorelease]; } - (NSAttributedString *)attributedStringForObjectValue:(id)anObject withDefaultAttributes:(NSDictionary *)attributes { return [[[NSAttributedString alloc] initWithString:[self stringForObjectValue:anObject] attributes:attributes] autorelease]; } - (BOOL)getObjectValue:(id *)anObject forString:(NSString *)string errorDescription:(NSString **)error { if(error) *error = @"Decoding roman numerals is currently unsupported"; return NO; } @end