Formatting a string containing a comma separated number

Question

I have a number stored in an NSMutableString instance that I want to automatically format with comma delimiters and then display the result in a UITextField .

I tried using NSNumberFormatter for formatting as a currency, but I do not want it to show decimal numbers if the original NSMutableString does not contain a decimal place.

For instance:

• If the NSMutableString contains "1234567", it should be formatted as "1,234,567".
• If the NSMutableString contains "1234567.1", it should be formatted as "1,234,567.1"
• If the NSMutableString contains "1234567.12", it should be formatted as "1,234,567.12"

The maximum decimal numbers that NSMutableString will contain are 2.

Any help is greatly appreciated.

Thanks!

Answer 1

Keep in mind that you really have to localize this if you interact with users on this, but this is one way to do this:

 - (NSString *)formatString:(NSString *)string { // Strip out the commas that may already be here: NSString *newString = [string stringByReplacingOccurrencesOfString:@"," withString:@""]; if ([newString length] == 0) { return nil; } // Check for illegal characters NSCharacterSet *disallowedCharacters = [[NSCharacterSet characterSetWithCharactersInString:@"0123456789."] invertedSet]; NSRange charRange = [newString rangeOfCharacterFromSet:disallowedCharacters]; if ( charRange.location != NSNotFound) { return nil; } // Split the string into the integer and decimal portions NSArray *numberArray = [newString componentsSeparatedByString:@"."]; if ([numberArray count] > 2) { // There is more than one decimal point return nil; } // Get the integer NSString *integer = [numberArray objectAtIndex:0]; NSUInteger integerDigits = [integer length]; if (integerDigits == 0) { return nil; } // Format the integer. // You can do this by first converting to a number and then back to a string, // but I would rather keep it as a string instead of doing the double conversion. // If performance is critical, I would convert this to a C string to do the formatting. NSMutableString *formattedString = [[NSMutableString alloc] init]; if (integerDigits < 4) { [formattedString appendString:integer]; } else { // integer is 4 or more digits NSUInteger startingDigits = integerDigits % 3; if (startingDigits == 0) { startingDigits = 3; } [formattedString setString:[integer substringToIndex:startingDigits]]; for (NSUInteger index = startingDigits; index < integerDigits; index = index + 3) { [formattedString appendFormat:@",%@", [integer substringWithRange:NSMakeRange(index, 3)]]; } } // Add the decimal portion if there if ([numberArray count] == 2) { [formattedString appendString:@"."]; NSString *decimal = [numberArray objectAtIndex:1]; if ([decimal length] > 0) { [formattedString appendString:decimal]; } } return formattedString; } // Test cases: NSLog(@"%@", [self formatString:@"123456"]); NSLog(@"%@", [self formatString:@"1234567."]); NSLog(@"%@", [self formatString:@"12345678.1"]); NSLog(@"%@", [self formatString:@"123456789.12"]); // Output: 123,456 1,234,567. 12,345,678.1 123,456,789.12 

Answer 2

Just let this method be simple:

 public static String GetCommaSeparatedCount(this Int32 Count) { // Check for The less-than character (<) is converted to &lt; String result = String.Format("{0:#,##0}", Count); return result; } 

Answer 3

You are looking for the -setMinimumFractionDigits: method for NSNumberFormatter. Set this value to 0, and it will only display the decimal point if anything is placed after it.

Answer 4

I think this should do it. I added an if statement to check if there is a decimal point in the entered value. The "exit" in this example is a property that I bound to the value of the text field to show the result.

 -(IBAction)doConversion:(id)sender{ NSNumberFormatter *formatter = [[NSNumberFormatter alloc]init]; [formatter setMaximumFractionDigits:2]; [formatter setUsesGroupingSeparator:YES]; [formatter setNumberStyle:NSNumberFormatterDecimalStyle]; double entryFieldFloat = [entryField doubleValue]; if ([entryField.stringValue rangeOfString:@"."].length == 1) { formatter.alwaysShowsDecimalSeparator = YES; self.output =[formatter stringFromNumber:[NSNumber numberWithDouble:entryFieldFloat]]; }else{ formatter.alwaysShowsDecimalSeparator = NO; self.output =[formatter stringFromNumber:[NSNumber numberWithDouble:entryFieldFloat]]; } }