python實例1-找質數/素數

質數定義：質數（prime number）又稱素數。質數定義為在大於1的自然數中，除了1和它本身以外不再有其他因數。

• 示例解決方案1

有很多方法可以解決這個問題，下面是一些例子:這是一個不同的功能分解來解決問題。

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."))

• 示例解決方案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.")

• 示例解決方案3

我覺得這是最簡潔的一種

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!")

以上就是解決找質數的三種方法，碰到一個問題要多想如何更加簡潔高效的實現功能，而不是實現了就行了，對自己要更高要求，這樣才會進步的更快。