#函数input()的工作原理：让程序暂停运行，等待用于输入一些文本。获取用户输入后，将其存放在一个变量中，以方便再使用。比如：
name = input("Please enter your name:")
print("Hello,"+name+" !")
#使用int()来获取数值输入。比如：
age = int(input("How old are you?"))
if age > 30:
print("奔4的人了！")
else:
print("你还年轻！")
#求模运算符：将两个数相除并返回余数。比如：
number = int(input("Enter a number,and I'll tell you if it's even or odd:"))
if number % 2 == 0:
print("The number "+str(number)+" is even.")
else:
print("The number "+str(number)+" is odd.")
#for循环和while循环区别：for循环用于针对集合中的每个元素的一个代码块，而while循环不断的运行，直到指定的条件不满足为止。比如：
current_number = 0
while current_number <= 5:
print(current_number)
current_number += 1
#让用户选择何时退出，比如：
prompt = "Tell me something,and I will repeat it back to you :"
prompt += "\nEnter 'quit' to end the program.\n"
message = "" #定义为空的理由是message符合条件，能够执行while循环
while message != 'quit':
message = input(prompt)
print(message)
#在要求很多条件都满足才继续运行的程序中，可定义一个变量，用来判断整个程序是否处于活动状态。这个变量称为标志，充当了程序的交通信号灯。可以让程序在标志为True时
#继续运行，并在任何事件导致标志的值为False时让程序停止运行。比如：
prompt = "Tell me something,and I will repeat it back to you :"
prompt += "\nEnter 'quit' to end the program.\n"
active = True
while active:
message = input(prompt)
if message == 'quit':
active = False
else:
print(message)
#使用break退出循环，注意：在任何python循环（遍历、while循环、for循环）中都可以使用break语句。比如：
prompt = "Tell me something,and I will repeat it back to you :"
prompt += "\nEnter 'quit' to end the program.\n"
while True:
message = input(prompt)
if message == 'quit':
break
else:
print(prompt)
#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。比如：
current_number = 0
while current_number < 10:
current_number += 1
if current_number % 2 == 0:
continue
print(current_number)
#使用while循环来处理列表和字典，不使用for循环的原因是在for循环中修改列表会导致python难以跟踪其中的元素。比如：
#在列表之间移动元素
unconfirmed_users = ['rose','jack','tony']
confirmed_users = []
while unconfirmed_users:
current_user = unconfirmed_users.pop()
print("Verify user: "+current_user.title())
confirmed_users.append(current_user)
print("The following users have been cnfirmed:")
for confirmed_user in confirmed_users:
print(confirmed_user)
#删除包含特定值的所有列表元素
pets = ["cat","dog","goldfish","cat","rabbit","tiger","cat","flyfish"]
print(pets)
while 'cat' in pets:
pets.remove('cat')
print(pets)
#使用用户输入来填充字典
reponses = {}
active = True
while active:
name = input("what's your name?")
mountain = input("which mountain would you like to climb someday?")
reponses[name] = mountain
message = input("would you like to let another person respond?(yes or no)")
if message == "no":
active = False
for key,value in reponses.items():
print(key.title() + " would like to climb " + value + " .")