[Python知识库]Python教程笔记----6小时完全入门

学习所看的视频来源于B站，授课老师：Mosh Hamedani老师

视频网址：python教程2019版 6小时完全入门 并且达到能开发网站的能力 目前最好的python教程 （含中文翻译）_哔哩哔哩_bilibili

执行Python代码

打开pycharm编辑器

新建一个Python?file

命名文件

编程

print("Mosh Hamedani")
print('o----')
print(' ||||')

运行：编辑完后Ctrl+'s'保存，然后右击鼠标run这个文件

变量：整数、浮点、字符串、布尔值

第一个程序

name=input('what is your name? ')
print('Hi '+name)

?第二个程序

字符串不能和整数、浮点数直接运算

birth_year=input('birth year: ')
age = 2019 - birth_year
print(age)

转换变量类型

整数? ? ? int（）

浮点型? float（）

布尔值? bool（）

1.

birth_year=input('birth year: ')
age = 2019 - int(birth_year)
print(age)

birth year: 2001
18

2.

weight_kg=input('weight(kg): ')
weight_lbs=int(weight_kg)/0.45
print(weight_lbs)

weight(kg): 46
102.22222222222221

3.引号

单引号、双引号

course1="python's course for beginners"
course2='python for "beginners'
print(course1)
print(course2)

python's course for beginners
python for "beginners

三引号

course='''
Hi John,

here is our first email to you.

thank you,
the support team
'''
print(course)

Hi John,

here is our first email to you.

thank you,
the support team

4.取值

course='python for beginners'
print(course[0])#正取值
print(course[-1])#逆取值
print(course[0:3])
print(course[0:8:2])#隔空取值
print(course[8:0:-1])#逆向隔空取值
print(course[:])#拷贝
print(course[0:])
print(course[0:len(course)])

p
s
pyt
pto 
of nohty
python for beginners
python for beginners
python for beginners

5.?

first="john"
last="smith"
massage=first+' ['+last+'] is a corder'
msg=f'{first} [{last}] is a corder'
print(massage)
print(msg)

john [smith] is a corder
john [smith] is a corder

6.大小写

course="Python for Beginners"
print(course.upper())
print(course.lower())
print(course.title())

PYTHON FOR BEGINNERS
python for beginners
Python For Beginners

find()

course="Python for Beginners"
print(course.find('P'))  #0
print(course.find('o'))  #4
print(course.find('0'))  #-1
print(course.find('Beginners'))  #11

replace()

print(course.replace('Beginners','Absolute Beginners'))  #Python for Absolute Beginners

#字符串中是否包含‘Python’?

print('Python'in course)  #True

基础运算

print(10+3)  #13
print(10-3)  #7
print(10*3)  #30
print(10**3)  #1000
print(10/3)  #3.3333333333333335
print(10//3)  #3
print(10%3)  #1

数学函数

四舍五入 round()? ? ? ? ? ? ? 绝对值abs()? ? ? ? ? ? ? ? ? ?.ceil()? ? ? ? ? ? ? ? ? ? .floor()

print(round(2.9))  #3
print(round(2.4))  #2
print(abs(-2.9))  #2.9
import math              #导入数字模块
print(math.ceil(2.9))  #3
print(math.floor(2.9))  #2

语句

实现下面文本要求

代码：

is_hot=False
is_cold=False
if is_hot:
    print('today is hot day')
    print('drink plenty of water')
elif is_cold:
    print('today is cold day')
    print('wear warm clothes')
else:
    print('today is lovely day')
print('Enjoy your day')

?练习

solution

price=1000000
has_good_credit = True
if has_good_credit:
    down_payment=price*0.1
else :
    down_payment=price*0.2
print(f"down payment is:{down_payment}")

down payment is:100000.0

逻辑运算符? (and? or? not)

练习

solution

has_high_income=True
has_good_credit=True
if has_high_income and has_good_credit:
    print("Eligible for loan")

?比较运算符（>? <? >=? <=? ==? !=）

练习1

?solution

temperature=30
if temperature > 30:
    print("it's a hot day")
elif temperature < 10:
    print("it's a cold day")
else:
    print("it's a neither hot or cold day")

练习2

?solution

name=input('name: ')
i=len(name)
if i<3:
    print('name must be at least 3 characters')
elif i>50:
    print('name can be a maximum of 50 characters')
else:
    print('name looks good!')

?

?体重单位 磅 和 千克 的转化器

solution

weight=int(input("weight: "))
unit=input("(L)bs or (K)g: ")
if unit.upper()=="L":
    i=weight*0.45
    print(f"You are {i} kilos")
elif unit.upper()=="K":
    i=weight/0.45
    print(f"You are {i} pounds")
else :
    print('please input l or k')

效果

?while?循环

简单的例子

i=1
while i<=5:
    print('*'*i)
    i+=1
print('Done')

*
**
***
****
*****
Done

?猜谜游戏

secret_number=9
guess_count=0
guess_limit=3
while guess_count<guess_limit:
    guess=int(input('guess: '))
    guess_count+=1
    if guess==secret_number:
        print('you won!')
        break
else:
    print('sorry,you failed!')

结果?

?练习

command= ""
started=False
while True:
    command=input("> ").lower()
    if command == "help":
        print('''
start - to start the car
stop - to stop the car
quit - to exit
        ''')
    elif command== 'start':
        if started:
            print('car is already started!')
        else:
            started=True
            print('Car started...')
    elif command == 'stop':
        if not started:
            print('car is already stopped')
        else:
            started=False
            print('Car stopped...')
    elif command == 'quit':
        break
    else:
        print("I don't understand that ...")

> HELP

start - to start the car
stop - to stop the car
quit - to exit
        
> start
Car started...
> start
car is already started!
> stop
Car stopped...
> stop
car is already stopped
> mac
I don't understand that ...
> quit

Process finished with exit code 0

for?循环

for item in 'Python':
    print(item)
for item in [1,2,3]:
    print(item)
for item in ['john','mosh','smith']:
    print(item)
for item in range(10):
    print(item)
for item in range(1,10,2):
    print(item)

P
y
t
h
o
n
1
2
3
john
mosh
smith
0
1
2
3
4
5
6
7
8
9
1
3
5
7
9

Process finished with exit code 0

练习

（还没看完视频，下午再接着写 。o 0）