python代码试图找到质数。代码计算的不是质数。找不到原因

Question

我试图在用户选择的范围内找到每个质数，列出它们并计算它们。我的代码计数和列表编号不是素数。我真的找不到为什么？有人可以帮帮我吗。

print("This code will count how many prime number exist in a certain range")
count = 0
lower = int(input("Enter lower range: "))
upper = int(input("Enter upper range: "))
prime = []
for num in range(lower, upper + 1):
    if num > 1:
        for i in range(2,num):
            if (num % i) == 0:
                break
            else:
                prime.append(num)
                break
print(prime)
print("There are", len(prime), "prime number between", lower, "and", upper)

Answer 1

问题就在这里，

    for i in range(2,num):
        if (num % i) == 0:    #If num is divisible by SOME i, it is not prime. Correct.
            break
        else:                 #If num is not divisible by SOME i, it is not prime. WRONG.
            prime.append(num)
            break

您应该像这样检查条件:如果 num 不能被任何 i 整除，则它是素数。

将 else 与 for 结合使用进行最少的更改，

    for i in range(2,num):
        if (num % i) == 0:
            break
    else:
        prime.append(num)

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阅读更多:Why does python use 'else' after for and while loops?