Python 相当于 Java 的标准 for 循环是什么？
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What is Python's equivalent of Java's standard for-loop?
提问by Deneb A.
I'm writing a simple algorithm to check the primality of an integer and I'm having a problem translating this Java code into Python:
我正在编写一个简单的算法来检查整数的素数，但在将此 Java 代码转换为 Python 时遇到了问题：
for (int i = 3; i < Math.sqrt(n); i += 2) {
if (n % i == 0)
return false;
}
So, I've been trying to use this, but I'm obviously skipping the division by 3:
所以，我一直在尝试使用它，但我显然跳过了 3 的除法：
i = 3
while (i < int(math.sqrt(n))):
i += 2 # where do I put this?
if (n % i == 0):
return False
回答by arshajii
The only for-loop in Python is technically a "for-each", so you can use something like
forPython 中唯一的-loop 在技术上是“for-each”，因此您可以使用类似
for i in xrange(3, int(math.sqrt(n)), 2): # use 'range' in Python 3
if n % i == 0:
return False
Of course, Python can do better than that:
当然，Python 可以做得更好：
all(n % i for i in xrange(3, int(math.sqrt(n)), 2))
would be equivalent as well (assuming there's a return trueat the end of that Java loop). Indeed, the latter would be considered the Pythonicway to approach it.
也将是等效的（假设return true在该 Java 循环的末尾有一个）。事实上，后者将被视为接近它的Pythonic方式。
Reference:
参考：
回答by duskwuff -inactive-
A direct translation would be:
直接翻译是：
for i in range(3, int(math.sqrt(n)), 2):
if n % i == 0:
return False
回答by mipadi
In a Java for loop, the step (the i += 2part in your example) occurs at the end of the loop, just before it repeats. Translated to a while, your for loop would be equivalent to:
在 Java for 循环中，步骤（i += 2示例中的部分）发生在循环的末尾，就在它重复之前。转换为一段时间，您的 for 循环将等效于：
int i = 3;
while (i < Math.sqrt(n)) {
if (n % i == 0) {
return false;
}
i += 2;
}
Which in Python is similar:
这在 Python 中是相似的：
i = 3
while i < math.sqrt(n):
if n % i == 0:
return False
i += 2
However, you can make this more "Pythonic" and easier to read by using Python's xrangefunction, which allows you to specify a stepparameter:
但是，您可以使用 Python 的xrange函数使其更“Pythonic”且更易于阅读，该函数允许您指定step参数：
for i in xrange(3, math.sqrt(n), 2):
if n % i == 0:
return False
回答by nanofarad
Use a basic Python for i in rangeloop:
使用基本的 Pythonfor i in range循环：
for i in range(3, math.round(math.sqrt(x)), 2):
if (n % i == 0):
return false
