Python中用户输入与while循环详情

msg = input('Please input a string: ') #引号中的内容应当向说明需要用户提供什么样的信息
#如果引号中的提示内容有多行，可以加入'\n'来换行
print('The message you just input is "' + msg + '".')

age = input('Please input your age: ')
age_integer = int(age)  #将数字字符串转换为数值

if age_integer >= 18:
    print('Your age is over 18.')
else:
    print('Your age is under 18.')

num = input('Please input a number: ')
number = int(num)
print('The number you just input is ' + num + '.')

if number%2 == 0: #可以整除2，是偶数
    print('It is an even number.')
else:  #不可以整除2，是奇数
    print('It is an odd number.')

num = 1
while num <= 5:
    print(num)
    num += 1   #不能使用num ++，一定要有这个条件，否则会进入无限循环

msg = ''
while msg != 'q':  #用户输入q时就退出循环
    msg = input("Enter 'q' to end the program.\nPlease input a string: ")
    if msg != 'q': #用户输入非q时打印用户输入信息
        print('The message you just input is "' + msg + '".')

sign = True
while sign:  #标志为True时执行循环
    msg = input("Enter 'q' to end the program.\nPlease input a string: ")
    
    if msg != 'q': #用户输入非q时打印用户输入信息
        print('The message you just input is "' + msg + '".')
    else:   #用户输入q时修改标志使其退出循环
        sign = False  #将标志置为False结束while循环

while True:  #执行循环
    msg = input("Enter 'q' to end the program.\nPlease input a string: ")
    
    if msg != 'q': #用户输入非q时打印用户输入信息
        print('The message you just input is "' + msg + '".')
    else:     #用户输入q时退出循环
        break #退出循环

num = 1
print('1-10之内的偶数:')
while num <= 10:
    num += 1
    
    if num % 2 != 0:
        continue   #奇数就跳过打印，偶数就执行打印
    print(num)

list_1 = ['abc', 'def', 'ghi']
list_2 = []
while list_1: #列表非空时一直循环
    element = list_1.pop()
    print(element + ' has popped.')
    
    list_2.append(element)
    
print('与原列表逆序输出:')
for element in list_2:
    print(element)
    
print('与原列表顺序输出:')
length = 1
while length <= len(list_2):
    print(list_2[-length])
    length += 1

fruits = ['grape', 'apple', 'watermelon', 'apple', 'orange', 'apple']
print('Before remove:\nfruits = '+str(fruits))

while 'apple' in fruits:
    fruits.remove('apple')  #删除列表中所有的'apple'元素
print('After remove:\nfruits = '+str(fruits))

user_info = {}  #创建一个空字典
sign = True  #标志位置为True
while sign:
    name = input("Please input your name: ")
    favorite_color = input("Please input your favorite color: ")
    
    user_info[name] = favorite_color  #在字典中添加键值对
    
    y_or_n = input("Enter 'n' to end, and other keys to continue.") #询问用户是否继续
    if y_or_n == 'n':
        sign = False  #标志位置为False并退出循环
        
print('user_info = '+str(user_info))  #打印字典

print("Information summary:")  #信息汇总输出
for name, favorite_color in user_info.items():  #遍历字典
    print(name + "'s favorite color is "  + favorite_color + '.')