How do I change the number of decimal places iOS? - ios

Question

I have a simple calculator app and I want it to be so that if the answer requires no decimal places, there are none, just whole numbers. If the answer was 2, I don't want it to say 2.000000, it should say 2. If it requires one decimal place, it should show to one decimal place for example 12.8 instead of 12.80. How would I do this? Here is my code.
btw, this is from a tutorial at http://www.youtube.com/watch?v=Ihw0cfNOrr4, not my own work.
viewcontroller.h
#import <UIKit/UIKit.h>
interface calcViewController : UIViewController {
float result;
IBOutlet UILabel *calculatorScreen;
int currentOperation;
float currentNumber;
}
-(IBAction)buttonDigitPressed:(id)sender;
-(IBAction)buttonOperationPressed:(id)sender;
-(IBAction)cancelInput;
-(IBAction)cancelOperation;
#end
in the .m
#import "calcViewController.h"
#implementation calcViewController
-(IBAction)buttonDigitPressed:(id)sender {
currentNumber = currentNumber *10 + (float)[sender tag];
calculatorScreen.text = [NSString stringWithFormat:#"%2f", currentNumber];
}
-(IBAction)buttonOperationPressed:(id)sender {
if (currentOperation ==0) result = currentNumber;
else {
switch (currentOperation) {
case 1:
result = result + currentNumber;
break;
case 2:
result = result - currentNumber;
break;
case 3:
result = result * currentNumber;
break;
case 4:
result = result / currentNumber;
break;
case 5:
currentOperation = 0;
break;
}
}
currentNumber = 0;
calculatorScreen.text = [NSString stringWithFormat:#"%2f", result];
if ([sender tag] ==0) result=0;
currentOperation = [sender tag];
}
-(IBAction)cancelInput {
currentNumber =0;
calculatorScreen.text = #"0";
}
-(IBAction)cancelOperation {
currentNumber = 0;
calculatorScreen.text = #"0";
currentOperation = 0;
}

Answer 1

One way is to use NSNumberFormatter to format your result instead of NSString's -stringWithFormat::
NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
[formatter setMaximumFractionDigits:requiredDigits];
[formatter setMinimumFractionDigits:0];
NSString *result = [formatter stringFromNumber:[NSNumber numberWithFloat:currentNumber];

Answer 2

The easiest way is just use [[NSNumber numberWithFloat:] stringValue]
Example:
float someFloatValue;
NSString floatWithoutZeroes = [[NSNumber numberWithFloat:someFloatValue] stringValue];

Answer 3

If we use %g in place of %f will truncate all zeros after decimal point.
For example
[NSString stringWithFormat:#"%g", 1.201000];
Output
1.201

Answer 4

This should work
NSString *result = [#(currentNumber) description];

Answer 5

I had the same problem. This is the code snippet that solved it (looks a lot like Caleb's solution, but that one didn't work for me, so I had to add an extra line):
NSNumberFormatter *numberFormatter = [[NSNumberFormatter alloc] init];
numberFormatter.numberStyle = kCFNumberFormatterDecimalStyle;
numberFormatter.maximumFractionDigits = 20;
numberFormatter.minimumFractionDigits = 0;
NSNumber *number = [[NSNumber alloc]init];
NSString *numberString = [numberFormatter stringFromNumber:number];
We can use another numberStyle and override its basic appearance, setting desired properties of an NSNumberFormatter.