xrange生成字符串？我不明白

Question

出于某种原因,在第一x变量for...循环从改变int到str通过代码的单次迭代后.我很困惑为什么必须这样,但每次我运行这个脚本时,我的集合最终会被包含数百个零的字符串填充.

如果有人好奇,这是尝试解决欧拉的问题4.

# A palindromic number reads the same both ways.
# The largest palindrome made from the product
# of two 2-digit numbers is 9009 = 91 99.
# Find the largest palindrome made from the product of two 3-digit numbers.

def palindrome():

    products = set()

    for x in xrange(700,999):
        for y in xrange(700,999):
            temp = x*y
            n = [x for x in str(temp)]
            if temp not in products:
                if len(n)%2 == 0:
                    half = len(n)/2
                    first = n[:half]
                    last = n[half:]
                    last.reverse()
                    if first == last:
                        products.add(temp)

    return products



if __name__ == "__main__":
    n = palindrome()
    print n

Answer 1

在python 2.x中,列表推导将其变量泄漏到封闭范围.所以你的列表理解会[x for x in str(temp)]覆盖x的值.但请注意,它将在外循环的下一次迭代中返回到int.