如何使我的for循环仅打印一次，而不是为每个i值打印一次

Question

我正在尝试创建一个函数，用于检查给定数字作为参数是否为素数。 我决定使用for循环来执行此操作，但它会不断输出该数字对于某些除法器而言不是素数，而对于其他数字而言则是素数。 这是我的代码：

def prime(n):
    for i in range(2, n):
        if n%i == 0:
            print (n," is not prime because it is divisible by ", i)

        else:
            print (n, " is a prime number")


prime (15)

这是输出：

15  is a prime number
15  is not prime because it is divisible by  3
15  is a prime number
15  is not prime because it is divisible by  5
15  is a prime number
15  is a prime number
15  is a prime number
15  is a prime number
15  is a prime number
15  is a prime number
15  is a prime number
15  is a prime number
15  is a prime number

因此，我不想立即将其作为输出，而是想立即认识到，如果该数字除以1以外还没有除数，则它不是质数。 如果没有。 有点像这样：

#if number if prime
15 is a prime number

#if number is not prime
15 is not a prime number because it is divisible by 3

Answer 1

通过return ，函数将在识别出数字不是质数时停止。

def prime(n):
    for i in range(2, n):
        if n%i == 0:
            print (n," is not prime because it is divisible by ", i)
            return 
    print (n, " is a prime number")
    return

这样的好处是，一旦表达式n%i == 0计算结果为true，它将打印并返回，从而停止进一步的不必要的计算。

Answer 2

尝试这个

def prime(n):
    for i in range(2, n):
        if n%i == 0:
            print (n," is not prime because it is divisible by ", i)

prime (15)

Answer 3

我会尝试类似的东西：

def prime(n): 
    isprime = True
    for i in range(2, n): 
         if n%i == 0:
              print (n," is not prime because it is divisible by ", i)
              isprime = False
              break
    if isprime:
         print (n, " is a prime number")
prime (15)