Learn the basics of Python 1

 

Python knowledge based on Python3.5

output Hello World

print（“HelloWorld”）

The python execution file does not pay attention to the suffix name but only the content, (.py is used to distinguish)

Variables and Data Types

Data types are roughly divided into three categories (dictionary list tuple and so on later), int (integer), string (string), boolean

int：

On a 32-bit machine, the number of integers is 32 bits, and the value range is -2**31~2**31-1, that is, -2147483648~2147483647

On a 64-bit system, the number of integers is 64 bits, and the value range is -2**63～2**63-1, that is, -9223372036854775808～9223372036854775807

str: the contents of single or double quotes, or multiple quotes (for multi-line strings)

Strings can be simply added and multiplied

 

 boolean:

TRUE and FALSE are mainly used to judge right or wrong (whether a statement is true)

name = "that kid" #Python does not need to define the data type name data type is string

age = 23 #age's data type is int

coding

Use utf-8 encoding

Notes

General use#

# name = "that boy" comment a single line

 

PEP8 check:

Comment on a single line: # +1 space + comment content

Comments following the code: 2 spaces+#+1 space+comment content

One blank line before the function, two blank lines before the class

Some words have always been underlined, you can right-click "Spelling" Typo: Save "XXX" to dictionary

 

""" """ or ''' '''Three double quotes or three single quotes Comment on multiple lines

‘’’

name = "that kid"

age = 23

‘’’

In addition to being able to comment multiple lines, you can also print multiple lines

but = 

‘’’

name = "that kid"

age = 23

‘’’

What print(mas) outputs is

enter

name = input（“name：”）

age = input（“age：”）

Note: The data type of input input is string by default, if you need to change it to integer

age = int(input("age:")) # data type is coerced to integer

Combining variables with strings

name = input ("name:") 
age = int(input("age:")) 
job = input("job:") 
infor = '''info of %s 
name:%s 
age:%d 
job:% s 
'''%(name,name,age,job) #This % is to associate the previous string with the variable in the brackets 
# A %s is a placeholder corresponding to the value in the brackets, s represents a string (character String), it can also be %d (specified as int type), the corresponding variable should also be int, and the variable of %s can be int.

age%d emphasizes that the input of age must be a number corresponding to the previous data type

infor2 = '''info of {0}
name:{0}
age:{1}
job:{2}
'''.format(name,age,job)

infor3 = '''info of {Name}
name:{Name}
age:{Age}
job:{Job}
'''.format(Name=name,Age=age,Job=job)

operator:

arithmetic operations

The following hypothetical variables: a=10, b=20

comparison operation

The following hypothetical variables: a=10, b=20

assignment operator

The following hypothetical variables: a=10, b=20

logic operation

call the standard library

#import getpass

#!/usr/bin/env python
import getpass
name = input("name:")
password = getpass.getpass("password:")
print(name,password)

if statement

#!/usr/bin/env python
import getpass
_name = "naxiaozi"
_password = "123"
name = input("name:")
password = getpass.getpass("password:")
if name == _name and _password == password:
    print("welcome")
else:
    print("name or password is wrong")

if: 
else: 
if: 
elif: 
Note: Python uses indentation to reflect the relationship between statements. 
If the condition is satisfied, the statement should be indented. The else is side by side with if, so there is no need to indent. 
while 
while True: 
while condition:

Exercise 1: Age Guessing Game (10 minutes)

Require:

1. The user is allowed to try at most 3 times. If the user fails to guess correctly after 3 attempts, he will exit directly. If he guesses correctly, print the congratulatory message and exit.

#!/usr/bin/env python

count = 0
old_of_boy = 23
while count < 3:
    count +=1
    guss_old = int(input("guss old:"))
    if old_of_boy == guss_old :
        print("yes,you get it")
        break
    elif old_of_boy > guss_old:
        print("think bigger")
    elif old_of_boy < guss_old:
        print("think smaller")

else :
    print("you have tried too many time ")
while的else只在中间不执行break才执行。

break to end the current loop 

continue to end the current loop and proceed to the next loop

for loop 
for i in range(10): #rang from 1 to 10 plus one each time, range (1:10:2) from 1 to 10 plus 2 each time 
print("loop:",i)

 

Exercise 2: Age Guessing Game Upgrade (10 minutes)

Require:

1. Allow users to try up to 3 times
2. After every 3 attempts, if the user has not guessed correctly, ask the user if he wants to continue playing. If the answer is Y or y, continue to let him guess 3 times, and so on. If the answer is N or n, exit the program
3. How to guess right, just quit

#!/usr/bin/env python
count = 0
old_of_boy = 23
while count < 3:
    count +=1
    guss_old = int(input("guss old:"))
    if old_of_boy == guss_old :
        print("yes,you get it")
        break
    elif old_of_boy > guss_old:
        print("think bigger")
    elif old_of_boy < guss_old:
        print("think smaller")
    if count == 3:
        print("是否还想猜：")
        k = input("想就输入‘是’，否则输入‘否’")
        if k == '是':
            count = 0
        elif k == 'N'or k == 'n':
            exit()
else :
    print("you have tried too many time ")