iPhone计算器十进制数字在输入时反转

While doing tutorial work, it took me forever to implement a decimal point, and now i have one, that works in the formula, but the issue is it reverses the input - e.g.. enter 1.4, the calculator screen shows it as 4.1 - i know its something to do with my housekeeping of the variables.. planning to use BOOL's instead of a float..but..any takers?

在做教程工作时,我花了很长时间来实现一个小数点,现在我有一个,在公式中工作,但问题是它反转输入 - 例如。输入1.4,计算器屏幕显示为4.1 - i知道它与我对变量的管理有关。计划使用BOOL而不是浮动......但是......任何接受者?

The code:

     - (IBAction) pressedDecimal: (id) sender
     {
       pressedDec = 1;
     }

    - (IBAction) pressedDigit: (id) sender 
     {
       if (pressedDec == 1) 
       {currentNumber = .1 * currentNumber + (double)[sender tag];
       calculatorScreen.text = [NSString stringWithFormat:@"%g",currentNumber];
      }
else

     {

       currentNumber =  currentNumber * 10 + (double)[sender tag];
       calculatorScreen.text = [NSString stringWithFormat:@"%g",currentNumber];
       pressedDec = 0;

      }
     }



  - (IBAction) pressedOperation: (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:@"%g",result];
if ([sender tag] == 0) result = 0;
currentOperation = [sender tag];
  }

2 个解决方案

#1

Consider more carefully what this extract from your code does:

更仔细地考虑代码中的这个摘录:

currentNumber = .1 * currentNumber + (double)[sender tag];

(I'm not being very explicit because if I've understood the question right you're doing this in order to learn, and the more you have to think the better you'll learn :-).)

(我不是很明确,因为如果我理解了这个问题,你就是为了学习而做的,而且你必须越多地认为你学得越好:-)。)

#2

-1

Lesson number 2 here: Stanford iTunes U tutorial covers building a simple calculator. Might be helpful. Either way it's a great tutorial series.

第2课:Stanford iTunes U教程包括构建一个简单的计算器。可能会有所帮助。无论哪种方式,它都是一个很棒的教程系列。

#1