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  • python系列(2) 函数

    3.1 def语句与参数

    def hello(name):
        print('Hello' +' ' +  name)
    hello('Alice')
    hello('Bob')
    

    3.2 返回值和return语句

    import random
    def getAnswer(answerNumber):
        if answerNumber == 1:
            return 'It is a certain'
        elif answerNumber == 2:
            return 'Yes'
        elif answerNumber == 3:
            return 'It is decidely so'
        elif answerNumber == 4:
            return 'Reply hazy try again '
        elif answerNumber == 5:
            return 'Ask again later'
        elif answerNumber == 6:
            return 'Concentrate and ask again'
        elif answerNumber == 7:
            return 'My replly is no'
        elif answerNumber == 8:
            return 'Out look not so good'
        elif answerNumber == 9:
            return 'Very doubtful'
    r = random.randint(1, 9)
    fortune = getAnswer(r)
    print(fortune)
    

    3.3 global语句

    如果需要在一个函数内修改全局变量,就会使用global语句。如果在函数的顶部有global eggs语句,就告诉python,eggs指代全局变量,所以不要用这个名字
    创建局部变量

    def spam():
        global eggs
        eggs = 'spam'
    eggs = 'global'
    spam()
    print(eggs)
    

    3.4 一个小程序,猜数字

    import random
    secretNumber = random.randint(1, 20)
    print('I am thinkinng of a number between 1 and 20')
    # ask the player too guess 6 times
    for guessesTaken in range(1, 7):
        print('Take a guess')
        guess = int(input())
        if guess < secretNumber:
            print('Your guess is too low')
        elif guess > secretNumber:
            print('Your guess is too high')
        else:
            break # this condition is the coorrect guess
    if guess == secretNumber:
        print('Good job! your guessd my number in' + str(guessesTaken) + 'guesses!')
    else:
        print('Nope, The number I was thinking of was' + str(secretNumber))
    

    实践项目

    编写一个名为collatz()的函数,他有一个名为number的参数,如果参数是偶数,那么collatz()就打印出number//2,并返回该值,如果Number是奇数,collatz()
    就打印并返回 3*number + 1
    然后编写一个程序,让用户输入一个整数,并不断对这个数调用collatz(),直到函数返回值为1

    def collatz(number):
        if number % 2 == 0:
            return a//2
        elif number % 2 !=0:
            return  3 * a + 1
    try:
        a = int(input('please input a number'))
        while True:
            a = collatz(a)
            if a ==  1:
                print(a)
                break
    except ValueError:
        print('Please input a right int num')
    
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  • 原文地址:https://www.cnblogs.com/yangjiez/p/12079944.html
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