問題描述
我有代碼來計算兩個數字之間的百分比差異 - (oldNum - newNum)/oldNum * 100; - 其中兩個數字都是 doubles.我希望在 oldNum 為 0 的情況下必須添加某種檢查/異常處理.但是，當我對 oldNum 和 newNum 的值都為 0.0 進行測試運行時，執行繼續進行，就好像什么都沒發生并且沒有引發錯誤一樣.使用 ints 運行此代碼肯定會導致算術除零異常.為什么Java在涉及到doubles時會忽略它?
I have code to calculate the percentage difference between 2 numbers - (oldNum - newNum) / oldNum * 100; - where both of the numbers are doubles. I expected to have to add some sort of checking / exception handling in case oldNum is 0. However, when I did a test run with values of 0.0 for both oldNum and newNum, execution continued as if nothing had happened and no error was thrown. Running this code with ints would definitely cause an arithmetic division-by-zero exception. Why does Java ignore it when it comes to doubles?
推薦答案
除以零的結果在數學上是undefined，可以用float/double表示(如NaN - 不是一個數字)，但它在任何基本意義上都沒有錯.
The result of division by zero is, mathematically speaking, undefined, which can be expressed with a float/double (as NaN - not a number), it isn't, however, wrong in any fundamental sense.
由于整數必須包含特定的數值，因此在處理它們時必須在除以零時引發錯誤.
As an integer must hold a specific numerical value, an error must be thrown on division by zero when dealing with them.
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