python基础语法

字符串

变量命名规则

变量名只能包含字母、 数字和下划线。 变量名可以字母或下划线打头， 但不能以数字打头， 例如， 可将变量命名为message_1， 但不能将其命名为1_message。
变量名不能包含空格， 但可使用下划线来分隔其中的单词。 例如， 变量名greeting_message可行， 但变量名greeting message会引发错误。
不要将Python关键字和函数名用作变量名， 即不要使用Python保留用于特殊用途的单词， 如print （请参见附录A.4） 。
变量名应既简短又具有描述性。 例如， name比n好， student_name比s_n好， name_length比length_of_persons_name好。
慎用小写字母l和大写字母O， 因为它们可能被人错看成数字1和0

修改字符串大小写

name="ada lovelace"
print(name.upper())
print(name.title())
print(name.lower())

字符串拼接

修改字符串大小写

使用+号拼接即可
name="hello"
name2="world"
print(name+name2)

rstrip删除末尾空白

language = 'python '
print(language)
print(language.rstrip())

lstrip删除开头空白

language = 'python '
print(language)
print(language.lstrip())

strip删除两端空白

language = ' python '
print(language)
print(language.strip())

数字转字符串 str()

age=23
print("age="+str(age))

列表

list = ['trek','cannondale','redline','special']
print(list)

访问元素

print(list[0])

添加元素

list.append("add");
print(list[-1])

插入数据

list.append(1,"insert")
print(list[1])

删除元素

del list[0]
print(list[0])

pop删除并返回栈顶数据

print(list.pop())

根据值删除

print(list.remove("insert"))

sort排序(字母排序)

cars = ['bmw','toyota','ben']
cars.sort();
print(cars)

sort排序(反字母排序)

cars = ['bmw','toyota','ben']
cars.sort(reverse=True);
print(cars)

sorted排序（不改变列表原来的顺序）

print(cars.sorted());
print(cars);

reverse 列表反转

cars = ['bmw','toyota','ben']
cars.reverse();
print(cars)

len 列表长度

print(cars.len())

列表遍历

magicians = ['alice', 'david', 'carolina']
for magician in magicians:
print(magician)

range() 生成范围内数值列表

for value in range(1,5):
    print(value)

numbers = list(range(1,5))
for value in numbers:
    print(value)

min,max,sum

min(list)
max(list)
sum(list)

列表切片

players = ['charles', 'martina', 'michael', 'florence', 'eli']
print(players[0:3])
print(players[:3])
print(players[2:])

复制列表

players = ['charles', 'martina', 'michael', 'florence', 'eli']
copyPlayers = players[:]

元组

元组中值固定不能修改，初始化时使用括号

dimensions = (200, 50)
print(dimensions[0])
print(dimensions[1])

元组遍历

dimensions = (200, 50)
for dimension in dimensions:
print(dimension)

输入

message = input("please write your name")
print(message);

输入整数

age = int("how old")
print(age)

求模

两数相除返回余数

>>>4%3
1
>>>5%3
2

while循环

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

prompt = "\nTell me something, and I will repeat it back to you:"
prompt += "\nEnter 'quit' to end the program. "
active = True
 while active:
	message = input(prompt)
 if message == 'quit':
	active = False
 else:
print(message)

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() + "!")

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

列表遍历

# 首先， 创建一个待验证用户列表
# 和一个用于存储已验证用户的空列表
unconfirmed_users = ['alice', 'brian', 'candace']
confirmed_users = []
# 验证每个用户， 直到没有未验证用户为止
# 将每个经过验证的列表都移到已验证用户列表中
while unconfirmed_users:
	current_user = unconfirmed_users.pop()
	print("Verifying user: " + current_user.title())
	confirmed_users.append(current_user)
# 显示所有已验证的用户
	print("\nThe following users have been confirmed:")
for confirmed_user in confirmed_users:
	print(confirmed_user.title())

函数

def greet_user(username):
"""显示简单的问候语"""
print("Hello, " + username.title() + "!")
greet_user('jesse')

def describe_pet(pet_name, animal_type='dog'):
"""显示宠物的信息"""
print("\nI have a " + animal_type + ".")
print("My " + animal_type + "'s name is " + pet_name.title() + ".")
describe_pet(pet_name='willie'

def get_formatted_name(first_name, last_name):
"""返回整洁的姓名"""
	full_name = first_name + ' ' + last_name
	return full_name.title()
musician = get_formatted_name('jimi', 'hendrix')
print(musician)

传入任意数量参数的函数

def make_pizza(*toppings):
"""打印顾客点的所有配料"""
print(toppings)
make_pizza('pepperoni')
make_pizza('mushrooms', 'green peppers', 'extra cheese')

类

创建类

class Dog():
"""一次模拟小狗的简单尝试"""
def __init__(self, name, age):
"""初始化属性name和age"""
	self.name = name
	self.age = age
def sit(self):
"""模拟小狗被命令时蹲下"""
	print(self.name.title() + " is now sitting.")
def roll_over(self):
"""模拟小狗被命令时打滚"""
	print(self.name.title() + " rolled over!")

使用子类

class Car():
"""一次模拟汽车的简单尝试"""
def __init__(self, make, model, year):
	self.make = make
	self.model = model
	self.year = year
	self.odometer_reading = 0
def get_descriptive_name(self):
	long_name = str(self.year) + ' ' + self.make + ' ' + 			 self.modelreturn long_name.title()
def read_odometer(self):
	print("This car has " + str(self.odometer_reading) + " miles on it.")
def update_odometer(self, mileage):
	if mileage >= self.odometer_reading:
		self.odometer_reading = mileage
	else:
		print("You can't roll back an odometer!")
def increment_odometer(self, miles):
	self.odometer_reading += miles
class ElectricCar(Car):
"""电动汽车的独特之处"""
def __init__(self, make, model, year):
"""初始化父类的属性"""
	super().__init__(make, model, year)
	my_tesla = ElectricCar('tesla', 'model s', 2016)
	print(my_tesla.get_descriptive_name())

导入类

class Battery():
"""一次模拟电动汽车电瓶的简单尝试"""
def __init__(self, battery_size=60):
	"""初始化电瓶的属性"""
	self.battery_size = battery_size
def describe_battery(self):
	"""打印一条描述电瓶容量的消息"""
	print("This car has a " + str(self.battery_size) + "-kWh battery.")
def get_range(self):
	"""打印一条描述电瓶续航里程的消息"""
	if self.battery_size == 70:
	range = 240
	elif self.battery_size == 85:
	range = 270
	message = "This car can go approximately " + str(range)
	message += " miles on a full charge."
	print(message)
class ElectricCar(Car):
"""模拟电动汽车的独特之处"""
def __init__(self, make, model, year):
	"""
	初始化父类的属性， 再初始化电动汽车特有的属性
	"""
	super().__init__(make, model, year)
	self.battery = Battery()