Python -- 5. 用户输入和while 循环

1. 函数input() 的工作原理
函数input() 让程序暂停运行，等待用户输入一些文本。获取用户输入后，Python将其存储在一个变量中.

message = input("Tell me something, and I will repeat it back to you: ")print(message)

(1). 使用int() 来获取数值输入
使用函数input() 时，Python将用户输入解读为字符串。

>>> age = input("How old are you? ")How old are you? 21>>> age'21'

函数int() 将数字的字符串表示转换为数值表示

height = input("How tall are you, in inches? ")height = int(height)if height >= 36:    print("\nYou're tall enough to ride!")else:    print("\nYou'll be able to ride when you're a little older.")

(2).求模运算符
处理数值信息时，求模运算符 （%）是将两个数相除并返回余数

number = input("Enter a number, and I'll tell you if it's even or odd: ")number = int(number)if number % 2 == 0:    print("\nThe number " + str(number) + " is even.")else:    print("\nThe number " + str(number) + " is odd.")

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2. while 循环简介
(1).使用while 循环

current_number = 1while current_number <= 5:    print(current_number)    current_number += 1

(2).使用break 退出循环
要立即退出while 循环，不再运行循环中余下的代码，也不管条件测试的结果如何，可使用break 语句。

prompt = "\nPlease enter the name of a city you have visited:"prompt += "\n(Enter 'quit' when you are finished.) "while True:    city = input(prompt)    if city == 'quit':        break    else:        print("I'd love to go to " + city.title() + "!")

(3).在循环中使用continue
要返回到循环开头，并根据条件测试结果决定是否继续执行循环，可使用

continue 语句current_number = 0while current_number < 10:    current_number += 1    if current_number % 2 == 0:        continue    print(current_number)