Limit a double to two decimal places without trailing zeros

问题

I read this and that. I want this exactly:

1.4324 => "1.43"
9.4000 => "9.4"
43.000 => "43"

9.4 => "9.40" (wrong)
43.000 => "43.00" (wrong)

In both questions the answers points to NSNumberFormatter. So it should be easy to achieve, but not for me.

- (void)viewDidLoad {
    [super viewDidLoad];
    UILabel *myLabel = [[UILabel alloc] initWithFrame:CGRectMake(50, 100, 200, 20)];

    NSNumberFormatter *doubleValueWithMaxTwoDecimalPlaces = [[NSNumberFormatter alloc] init];
    [doubleValueWithMaxTwoDecimalPlaces setNumberStyle:NSNumberFormatterDecimalStyle];
    [doubleValueWithMaxTwoDecimalPlaces setPaddingPosition:NSNumberFormatterPadAfterSuffix];
    [doubleValueWithMaxTwoDecimalPlaces setFormatWidth:2];

    NSNumber *myValue = [NSNumber numberWithDouble:0.01234];
    //NSNumber *myValue = [NSNumber numberWithDouble:0.1];

    myLabel.text = [doubleValueWithMaxTwoDecimalPlaces stringFromNumber:myValue];

    [self.view addSubview:myLabel];
    [myLabel release];
    myLabel = nil;
    [doubleValueWithMaxTwoDecimalPlaces release];
    doubleValueWithMaxTwoDecimalPlaces = nil;
}

I also tried it with

NSString *resultString = [NSString stringWithFormat: @"%.2lf", [myValue doubleValue]];
NSLog(@"%@", resultString);

So how can I format double values with maximum two decimal places? If the last position contains a zero the zero should be left out.

Solution:

NSNumberFormatter *doubleValueWithMaxTwoDecimalPlaces = [[NSNumberFormatter alloc] init];
[doubleValueWithMaxTwoDecimalPlaces setNumberStyle:NSNumberFormatterDecimalStyle];
[doubleValueWithMaxTwoDecimalPlaces setMaximumFractionDigits:2];
NSNumber *myValue = [NSNumber numberWithDouble:0.01234];
NSLog(@"%@",[doubleValueWithMaxTwoDecimalPlaces stringFromNumber:myValue]];
[doubleValueWithMaxTwoDecimalPlaces release];
doubleValueWithMaxTwoDecimalPlaces = nil;

回答1:

Try adding the following line, when configuring your formatter:

    [doubleValueWithMaxTwoDecimalPlaces setMaximumFractionDigits:2];

回答2:

How about trimming the unwanted characters from the end of the string?:

NSString* CWDoubleToStringWithMax2Decimals(double d) {
    NSString* s = [NSString stringWithFormat:@"%.2f", d];
    NSCharacterSet* cs = [NSCharacterSet characterSetWithCharacterInString:@"0."];
    NSRange r = [s rangeOfCharacterInSet:cs
                                 options:NSBackwardsSearch | NSAnchoredSearch];
    if (r.location != NSNotFound) {
      s = [s substringToIndex:r.location];
    }
    return s;
}

回答3:

 NSNumberFormatter *numberFormatter = [[NSNumberFormatter alloc] init];
[numberFormatter setNumberStyle:NSNumberFormatterDecimalStyle];
[numberFormatter setRoundingMode:NSNumberFormatterRoundDown];
[numberFormatter setMinimumFractionDigits:2];
numberFormatter.positiveFormat = @"0.##";
NSNumber *num = @(total_Value);

来源：https://stackoverflow.com/questions/4026135/limit-a-double-to-two-decimal-places-without-trailing-zeros

标签

iphone

objective-c

cocoa-touch

decimal

nsnumberformatter