How can I pad an integer on the left with zeros?

Question

I have the following variable:

NSNumber *consumption = [dict objectForKey:@\"con\"];

Which returns 42. How can I pad this number to 10 dig

Answer 1

E.g. Fill the rest with zeros, 5 digits:

NSInteger someValue = 10;
[NSString stringWithFormat:@"%05ld", someValue];

Equivalent of .02f for float number when you need only 2 digits after the dot.

So there you have 0 = fill with zeros, 5 = the number of digits and type.

Answer 2

You can't in the NSNumber itself. If you're creating a string from the number or using NSLog(), simply use the appropriate format, e.g.

NSLog(@"%010d", [consumption intValue]);

Answer 3

The Objective-C way,

NSNumberFormatter * numberFormatter = [[[NSNumberFormatter alloc] init] autorelease];
[numberFormatter setPaddingPosition:NSNumberFormatterPadBeforePrefix];
[numberFormatter setPaddingCharacter:@"0"];
[numberFormatter setMinimumIntegerDigits:10];

NSNumber * number = [NSNumber numberWithInt:42];

NSString * theString = [numberFormatter stringFromNumber:number];

NSLog(@"%@", theString);

The C way is faster though.

Answer 4

Solution for Swift 3

let x = 1078.1243
let numFormatter = NumberFormatter()
numFormatter.minimumFractionDigits = 1 // for float
numFormatter.maximumFractionDigits = 1 // for float
numFormatter.minimumIntegerDigits = 10 // how many digits do want before decimal
numFormatter.paddingPosition = .beforePrefix
numFormatter.paddingCharacter = "0"

let s = numFormatter.string(from: NSNumber(floatLiteral: x))!

OUTPUT

"0000001078.1"

Answer 5

You can do pretty much any number formatting you would ever want with NSNumberFormatter. In this case I think you would want to use the setFormatWidth: and setPaddingCharacter: functions.

Answer 6

NSString *paddedStr = [NSString stringWithFormat:@"%010d", 42];

EDIT: It's C style formatting. %nd means the width is at least n. So if the integer is 2 digit long, then you will have length 3 string (when %3d is used). By default the left empty spaces are filled by space. %0nd (0 between % and n) means 0 is used for padding instead of space. Here n is the total length. If the integer is less than n digits then left padding is used.