iOS:NSDecimalNumber:没有得到预期的结果

Question

假设我对这些 ivar 具有以下值:

NSString* 百分比 = 35 NSString* 值 = 146

在我下面的代码中，当我进行乘法 (146*.35) 时，我期望得到 51.1，但结果却是 100。

- (NSDecimalNumber*) getProductByPercentage : (NSArray*) itemsToMultiply : (float) annualPatients {

    //get items from array
    NSString* percentage = [itemsToMultiply objectAtIndex:0];
    NSString* value = [itemsToMultiply objectAtIndex:1];

    //init a number formatter
    NSNumberFormatter * f = [[NSNumberFormatter alloc] init];
    //set its formatting style
    [f setNumberStyle:NSNumberFormatterDecimalStyle];

    //convert to percentage
    float thisPercentage = [percentage floatValue]/100;

    //convert to NSDecimal
    NSDecimalNumber* decPercentage = [[NSDecimalNumber alloc] initWithString:[NSString stringWithFormat:@"%f",  thisPercentage]];
    NSDecimalNumber* decAvgReimbursement = [[NSDecimalNumber alloc] initWithString: value];
    NSDecimalNumber* decAnnualPatients = [[NSDecimalNumber alloc] initWithString:[NSString stringWithFormat:@"%f", annualPatients]];

    //set up handler
    NSDecimalNumberHandler *handler = [NSDecimalNumberHandler decimalNumberHandlerWithRoundingMode:NSRoundPlain
            scale:-2
            raiseOnExactness:NO
            raiseOnOverflow:NO
            raiseOnUnderflow:NO
            raiseOnDivideByZero:NO
    ];

    //get our results
    NSDecimalNumber* decAvgCost = [decAvgReimbursement decimalNumberByMultiplyingBy:decPercentage
                                                                 withBehavior:handler];

    NSLog(@"%@::%@::%@", decAvgCost, decAvgReimbursement, decPercentage);

    return decAvgCost;
}

这是我的日志输出

2013-02-04 13:57:46.960 EUS Calculator[34154:c07] 100::146::0.35

我的处理程序是否有问题导致我得到错误的结果？

Answer 1

scale:-2

您将比例设置为四舍五入到 -2 位小数，即最接近的 100。