Question

我必须编写一个程序，用户在其中输入数字，然后检查它是否为素数，但是无论您输入什么，它都会说素数。如何解决此代码？

def is_prime(n):
    if n < 2: return False
    for x in range(2, int(n**0.5) + 1):
        if n % x == 0:
            return False
    return True

def main():
    keep_going='y'
    while keep_going=='y':
        n=int(input("Please enter a number to see if it's prime: "))
        is_prime(n)
        if True:
            print("It's prime")
        if False:
            print("it's not prime")
        keep_going=input("would you like to see if another number is prime? (y/n):")

main()

Answer 1

这样做

while keep_going=='y': n=int(input("Please enter a number to see if it's prime: ")) if is_prime(n): print("It's prime") else: print("it's not prime") keep_going=input("would you like to see if another number is prime? (y/n):")

Answer 2

您没有在任何地方分配is_prime(n)的返回值，也没有测试该返回值。 if True:是无条件执行。 if False:是无条件不执行。

相反，您想测试is_prime(n)：

if is_prime(n):
    ...
else:
    ...

或

prime = is_prime(n)
if prime:
    ...
else:
    ...

好消息是-您的is_prime函数正确，并且确实返回了非质数的False：）

Answer 3

尝试一下

def is_prime(n):
    if n < 2:
        return False
    elif n % (n // 2) == 0:
        return True
    else:
        return False


def main():
    keep_going = 'y'
    while keep_going == 'y':
        n = int(input("Please enter a number to see if it's prime: "))
        if is_prime(n):
            print("It's prime")
        else:
            print("it's not prime")
        keep_going = input("would you like to see if another number is prime?(y/n):")


main()

为什么我的素数检查程序总是说数字是素数？

3 个答案: