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冷日 (冷日) |
發表時間:2008/12/5 9:30 |
- Webmaster
- 註冊日: 2008/2/19
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- 發表數: 15771
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- [自創]測試Java的四捨五入、無條件捨去、無條件進位
- 今天因為公司同仁提到,在VBA裡面round函式居然是做『偶數四捨五入』!
冷日還搞了辦天才搞懂何謂『偶數四捨五入』ㄌㄟ! 討論討論就發現,我們應該來看看Java對於四捨五入的準確度!
/* ========================================================================== */
/* TestRound.java
/* (c) 2005 Author 冷日
/* Description
/* 因為冠宇說VBA裡面的round會做『偶數四捨五入』,12.5四捨五入=12 、 13.5四捨五入=14 、 10.5四捨五入=10 、 11.5四捨五入=12
/* 所以來測試Java的Round,雖然冷日覺得就是M$在耍白痴!(順便測無條件進位ceil和捨去floor)
/* ========================================================================== */
import java.io.*;
import java.lang.*;
class TestRound {
public static void main(String[] args) {
double x = 11.3 , y = 12.6 , z = 13.52145 ;
System.out.println( "x is " + x + " after round is " + (int)Math.round(x) + "!" );
System.out.println( "y is " + y + " after round is " + (int)Math.round(y) + "!" );
System.out.println( "z is " + z + " after round is " + (int)Math.round(z) + "!");
System.out.println( "x is " + x + " after floor is " + (int)Math.floor(x) + "!" );
System.out.println( "x is " + x + " after ceil is " + (int)Math.ceil(x) + "!" );
System.out.println( "z is " + z + " after floor is " + (int)Math.floor(z) + "!");
System.out.println( "z is " + z + " after ceil is " + (int)Math.ceil(z) + "!");
}
}
答案如下:
---------- Run ----------
x is 11.3 after round is 11!
y is 12.6 after round is 13!
z is 13.52145 after round is 14!
x is 11.3 after floor is 11!
x is 11.3 after ceil is 12!
z is 13.52145 after floor is 13!
z is 13.52145 after ceil is 14!
Normal Termination
輸出完成 (耗時 0 秒).
看起來都是正確低,相信Java果然是對低!
Math的三大函式解說: 四捨五入:Math.round() 取小於這個數的最大整數:Math.floor() 取大於這個數的最小整數:Math.ceil()
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