java-在Python v 3.5.2和v 2.7.12中结果不同,但是v 2.7.12是正确的吗?
内容导读
互联网集市收集整理的这篇技术教程文章主要介绍了java-在Python v 3.5.2和v 2.7.12中结果不同,但是v 2.7.12是正确的吗?,小编现在分享给大家,供广大互联网技能从业者学习和参考。文章包含3724字,纯文字阅读大概需要6分钟。
内容图文
![java-在Python v 3.5.2和v 2.7.12中结果不同,但是v 2.7.12是正确的吗?](/upload/InfoBanner/zyjiaocheng/669/5c9c3844072d4e4ab1e1986e11627210.jpg)
首先,我要说一下我的问题,我知道在Python 3周围,“无限长”已集成到int中,因此Python中的int有效地可以和您的RAM一样大.
我正在比较Java和Python.
以下是Python和Java程序.他们做同样的事情.
Python:
def answer(n):
count = 0
t = int(n)
while (t!=1):
t = t+1 if (t%2==1) else t/2
count += 1
return count
Java:
static int answer(String n){
int count = 0;
BigInteger t = new BigInteger(n)
while(!t.equals(BigInteger.ONE)){
t = ((t.remainder(new BigInteger("2"))).equals(BigInteger.ONE))
?t.add(new BigInteger("1"))
:t.divide(new BigInteger("2"));
count++;
}
return count;
}
然后,我编写了一个简单的bash脚本来运行java和python(版本2.7.12和3.5.2)并比较它们的输出.
#!/bin/bash
i=$1
a=`java Solution $i`
b=`python Solution.py $i`
c=`python3 Solution.py $1`
echo "INPUT: $1"
echo ""
echo "LANGUAGE: VERSION: RESULT:"
echo "-------- --------- ------"
echo "Java 1.8.0_151 $a"
echo "Python 2.7.12 $b"
echo "Python3 3.5.2 $c"
这是一些示例运行. RESULT列很重要.
INPUT: 123
LANGUAGE: VERSION: RESULT:
-------- --------- ------
Java 1.8.0_151 9
Python 2.7.12 9
Python3 3.5.2 9
INPUT: 123456789
LANGUAGE: VERSION: RESULT:
-------- --------- ------
Java 1.8.0_151 39
Python 2.7.12 39
Python3 3.5.2 39
INPUT: 12345678998765
LANGUAGE: VERSION: RESULT:
-------- --------- ------
Java 1.8.0_151 61
Python 2.7.12 61
Python3 3.5.2 61
INPUT: 123456789987654321
LANGUAGE: VERSION: RESULT:
-------- --------- ------
Java 1.8.0_151 84
Python 2.7.12 84
Python3 3.5.2 82
因此,在输入变得足够大之前,它们几乎都产生相同的结果,然后对于最后一个输入,您可以看到结果是不同的.几乎每个大于此的数字都会产生不同的结果.
Python3的int和Java的BigInteger是否应该得到相同的结果?
Python v.2难道不是获得不同结果的人吗?
哪一个实际上是错误的,为什么? Java和Python3还是Python v.2.7.12?
我如何纠正任何错误才能获得正确的输出?
解决方法:
该问题实际上与Python 2中整数文字的限制无关.这只是一个红鲱鱼.您的真正问题是除法运算符/在Python 2中的行为与在Python 3中的行为不同.
PEP 238 documents this change:
The current division (/) operator has an ambiguous meaning for numerical arguments: it returns the floor of the mathematical result of division if the arguments are ints or longs, but it returns a reasonable approximation of the division result if the arguments are floats or complex. This makes expressions expecting float or complex results error-prone when integers are not expected but possible as inputs.
We propose to fix this by introducing different operators for different operations: x/y to return a reasonable approximation of the mathematical result of the division (“true division”), x//y to return the floor (“floor division”). We call the current, mixed meaning of x/y “classic division”.
Because of severe backwards compatibility issues, not to mention a major flamewar on c.l.py, we propose the following transitional measures (starting with Python 2.2):
Classic division will remain the default in the Python 2.x series;
true division will be standard in Python 3.0.The // operator will be available to request floor division
unambiguously.The future division statement, spelled from
__future__ import
, will change the
division/
operator to mean true division throughout
the module.A command line option will enable run-time warnings for classic
division applied to int or long arguments; another command line
option will make true division the default.The standard library will use the future division statement and the
//
operator when appropriate, so as to completely avoid classic
division.
因此,如果您希望当输入为123456789987654321时Python代码正确运行,则需要使用下限除法运算符//:
def answer(n):
count = 0
t = int(n)
while t != 1:
t = t + 1 if (t % 2==1) else t // 2
count += 1
return count
内容总结
以上是互联网集市为您收集整理的java-在Python v 3.5.2和v 2.7.12中结果不同,但是v 2.7.12是正确的吗?全部内容,希望文章能够帮你解决java-在Python v 3.5.2和v 2.7.12中结果不同,但是v 2.7.12是正确的吗?所遇到的程序开发问题。 如果觉得互联网集市技术教程内容还不错,欢迎将互联网集市网站推荐给程序员好友。
内容备注
版权声明:本文内容由互联网用户自发贡献,该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务,不拥有所有权,不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容, 请发送邮件至 gblab@vip.qq.com 举报,一经查实,本站将立刻删除。
内容手机端
扫描二维码推送至手机访问。