python - 对于循环重复/卡住？ Python 3.2

Question

我正在尝试为埃拉托色尼筛法编写一个 Python 脚本。我已完成所有操作，但是当我告诉程序测试每个数字是否是√输入下方至少一个质数的倍数时。一切顺利，但是当我尝试删除一个倍数时，它一直有效，直到它尝试删除 6 两次……我一直在查看我的代码，但似乎无法找出原因。我是 Python 的新手，所以非常感谢您的帮助!--- 请注意，由于 SOF 制作代码块的方式，我的代码的间距已关闭:

import math, os, threading

global iswhole
global tdprime

def iswhole(x):
if x%1 == 0:
    return True
else:
    return False

def tdprime(x):
prime = True
n = 2

while n < x:
    if iswhole(x/n) == True:
        return False
        prime = False
        n = x
    else:
        n += 1

if prime == True:
    return True

number = 0

while number != 1:

number = int(input("Enter number to calculate all primes up to:  "))
number_range = range(1,number+1)
sqrt = math.sqrt(number)
rsqrt = round(sqrt)
thelist = []
tsl = []

for num in range(1,rsqrt):
    if tdprime(num) == True:
        tsl.append(num)
tsl.remove(1)

for x in number_range: ## Making the List
    thelist.append(x)
    ## Note it's " Key: Value " in dictionaries

print(tsl)
print("thelist: ",thelist)
print("Square root of input = ",sqrt)
print("Rounded Square root of input = ",rsqrt)
print()

for x in thelist: ## Testing each number in thelist

    multiple = False

    for y in tsl: ## Each prime number under √number

        if iswhole(x/y):
            print(x) ## If the current number in thelist divided by one of the prime numbers under √number is a whole
            thelist.remove(x)## Remove the current number which isn't a prime
            thelist.sort()
            multiple = True ## Make multiple true so it doesn't print (could remove the multiple stuff and other if function, kind of pointless function now)

    if multiple == False:
        print("Prime! ",x)


print(thelist)

Answer 1

您的代码可以通过以下实现大大简化:

• 最多 n 的数字可以根据需要轻松生成，它们不必预先计算并存储在列表中。

• 2 是唯一的偶素数，所以你只需要测试奇数。

• 所有数字都可以唯一地完全分解为质因式(这称为算术基本定理)。这意味着您需要尝试除以的唯一数字是您之前计算的素数 --- 所有其他数字都将至少被这些素数中的一个整除(或者它们本身就是素数)。

按照这些思路尝试一些事情:

stop = int(input("Enter number to calculate all primes up to: "))

primes = []

for n in range(3, stop, 2): # Step by two each time
    was_prime = True # Needed to break out of nested loop
    for p in primes:
        if n % p == 0: # A prime divides n
             was_prime = False
             break # No need to continue
    if was_prime:
        primes.append(n)

print(primes) # You can insert the number 2 here if you like

另外，请注意间距和缩进。在 Python 中，当你的间距错误时，不仅难以阅读，而且会导致运行时错误。