Python学习笔记-基础语法1、int()函数：，我来为大家讲解一下关于2022年5月19日学习笔记-基础语法?跟着小编一起来看一看吧!
2022年5月19日学习笔记-基础语法
Python学习笔记-基础语法
第七章 用户输入和while循环- 一、input()函数
- 二、while循环
- 三、使用while循环来处理列表和字典
1、int()函数：
- input()函数输出为字符串，使用int()将之转换为数值
age = input("请输入你的年龄：")
print(age >= 19)
输出结果为：
请输入你的年龄：11
Traceback (most recent call last):
File "D:\Python_Work\Python学习\Python编程-从入门到实践\练习.py", line 2, in <module>
print(age >= 19)
TypeError: '>=' not supported between instances of 'str' and 'int'
2、求模求商
|
方法 |
描述 |
|
% |
求模，取余数。可取2模以判断奇偶 |
|
// |
求商 |
>>> 10 // 2
5
>>> 10 % 2
0
prompt = "\nTell me something, and I will repeat it back to you: "
prompt = "\nEnter 'quit' to end the program. " "\n"
message = ''
while message != 'quit':
message = input(prompt)
if message != 'quit':
print(message)
输出结果为：
Tell me something, and I will repeat it back to you:
Enter 'quit' to end the program.
你好帅啊
你好帅啊
Tell me something, and I will repeat it back to you:
Enter 'quit' to end the program.
quit
1、使用标志高效运行while循环
prompt = "\nTell me something, and I will repeat it back to you: "
prompt = "\nEnter 'quit' to end the program. " "\n"
active = True #标志
while active:
message = input(prompt)
if message == 'quit':
active = False
else:
print(message)
输出结果：
Tell me something, and I will repeat it back to you:
Enter 'quit' to end the program.
你好帅啊
你好帅啊
Tell me something, and I will repeat it back to you:
Enter 'quit' to end the program.
quit
2、使用break退出循环
prompt = "\nTell me something, and I will repeat it back to you: "
prompt = "\nEnter 'quit' to end the program. " "\n"
while True:
city = input(prompt)
if city == 'quit':
break
输出结果为：
Tell me something, and I will repeat it back to you:
Enter 'quit' to end the program.
你好帅啊
Tell me something, and I will repeat it back to you:
Enter 'quit' to end the program.
quit
- 在任何Python循环中都可以使用break语句
- 可使用break语句来退出遍历列表或字典的for循环
3、在循环中使用continue
- continue：回到循环开头，根据条件测试结果决定是否继续执行循环
- 它不像break语句那样不再执行余下的代码并推出整个循环
current_number = 0
while current_number < 10:
current_number = 1
if current_number %2 == 0:
continue #如果符合条件测试，continue让他回到while重新执行，直到不符合条件测试，打印current_number
print(current_number)
输出结果为：
1
3
5
7
9
- for循环中不应修改列表，否则将导致Python难以跟踪其中的元素
- 要在遍历列表的同时对其进行修改，可使用while循环
1、在列表之间移动元素
unconfirmed_users = ['alice','brian','candace']
confirmed_users = []
while unconfirmed_users: #列表空则为False
current_user = unconfirmed_users.pop()
print("Verifying user: " current_user.title())
confirmed_users.append(current_user)
print("\nThe following users have been confirmed: ")
for confirmed_user in confirmed_users:
print(confirmed_user)
输出结果为：
Verifying user: Candace
Verifying user: Brian
Verifying user: Alice
The following users have been confirmed:
candace
brian
alice
2、删除包含特定值得所有列表元素
pets = ['dog','cat','dog','goldfish','cat','rabbit','cat']
print(pets)
while 'cat' in pets:
pets.remove('cat')
print(pets)
输出结果为：
['dog', 'cat', 'dog', 'goldfish', 'cat', 'rabbit', 'cat']
['dog', 'dog', 'goldfish', 'rabbit']
3、使用用户输入来填充字典
responses = {}
polling_active = True
while polling_active:
name = input("\nWhat is your name?\n ")
response = input("Which mountain would you like to climb someday? \n")
responses[name] = response
repeat = input("Would you like to let another person respond? (yes/no) \n")
if repeat == 'no':
polling_active = False
print("\n--- Poll Results ---")
for name, response in responses.items():
print("\n" name.title() " would like to climb " response ".\n")
输出结果为：
What is your name?
小明
Which mountain would you like to climb someday?
黄山
Would you like to let another person respond? (yes/no)
yes
What is your name?
小刚
Which mountain would you like to climb someday?
泰山
Would you like to let another person respond? (yes/no)
no
--- Poll Results ---
小明 would like to climb 黄山.
小刚 would like to climb 泰山.
