python实例1-找质数/素数

质数定义：质数（prime number）又称素数。质数定义为在大于1的自然数中，除了1和它本身以外不再有其他因数。

• 示例解决方案1

有很多方法可以解决这个问题，下面是一些例子:这是一个不同的功能分解来解决问题。

def get_number(prompt):
    '''Returns integer value for input. Prompt is displayed text'''
    return int(input(prompt))

def is_prime(number):
    '''Returns True for prime numbers, False otherwise'''
    # Edge Cases
    if number == 1:
        prime = False
    elif number == 2:
        prime = True
    # All other primes
    else:
        prime = True
        for check_number in range(2, (number / 2) + 1):
            if number % check_number == 0:
                prime = False
                break
    return prime

def print_prime(number):
    prime = is_prime(number)
    if prime:
        descriptor = ""
    else:
        descriptor = "not "
    print(number, " is ", descriptor, "prime.", sep="", end="\n\n")

# never ending loop

while 1 == 1:
    print_prime(get_number("Enter a number to check. Ctl-C to exit."))

• 示例解决方案2

import sys
number = input("Please enter a number" + "\n" + ">>>")
number = int(number)
if number > 0:
    for x in range (2, number): #this range excludes number and 1, both of which number is divisible by
        if number % x != 0: #If number isn't evenly divisible by x, start over with the next one
            continue
        elif number % x == 0: #If number is evenly divisible by x, it can't be prime
            sys.exit("The number is not prime.")
    sys.exit("The number is prime.") #number wasn't evenly divisible by any x, so it's prime
elif number == 0:
    sys.exit("The number is not prime.") #According to the Google, 0 is not prime
else:#if number is less than 0, the number is not prime (according to the Google).
    sys.exit("The number is not prime.")

• 示例解决方案3

我觉得这是最简洁的一种

def prime(n):
    factor=[i for i in range(2,n) if n%i ==0]
    if len(factor)==0:
        print(str(n)+"is prime!")
    elif n==2:print(str(n)+" " +"is prime!")
    else:print("not prime!")

以上就是解决找质数的三种方法，碰到一个问题要多想如何更加简洁高效的实现功能，而不是实现了就行了，对自己要更高要求，这样才会进步的更快。