What you need to pay attention to when learning Python

Hello World

Use the print() method to print HelloWorld
name = "Jenkin Li"

print("My name is ", name)

Encoding issues in Python 2.x

Because Python 2.x uses ASCII encoding and does not support Chinese by default. You must declare in the file header what encoding the file uses.
# -- coding:utf-8 --

Python comments

are divided into single-line comments and multi-line comments
# Single-line comments
'''
Multi-line comments
'''

Python text formatted output

1. Use placeholders such as %s, %d

name = input("name: ")
age = input("age: ")
job = input("job: ")
salary = input("salary: ")
info = '''
---------- info of %s ---------
Name: %s
Age: %s
job: %s
salary: %s
''' % (name, name, age, job, salary)

print(info)

PS: If you use %d, you must use int() to convert to numeric type, input Type defaults to string. In contrast to int(), str() converts a numeric type to a string.
In Python, values ​​and strings cannot be connected through the + sign. They must be converted first

2. Use parameters to format the output

info = '''
---------- info of {_name} ---------
Name: {_name}
Age: {_age}
job: {_job}
salary: {_salary}
'''.format(_name = name,
           _age = age,
           _job = job,
           _salary = salary)

3. Use Subscript formatted output

info = '''
---------- info of {0} ---------
Name: {0}
Age: {1}
job: {2}
salary: {3}
'''.format(name, age, job, salary)

Use the getpass module to hide the password entered by the user

import getpass
username = input("username: ")
password = getpass.getpass("password: ")
print(username)
print(password)

It should be noted that the above code cannot be run in IDEs such as PyCharm and must be run in the terminal Run in

Use the type() function to obtain the variable type

type(variable)

while … else statement

count = 0
while count < 3:
    guess_age = int(input("guess age: "))
    if guess_age == age_of_oldboy:
        print("yes, you got it")
        break
    elif guess_age > age_of_oldboy:
        print("Ooops, think smaller...")
    else:
        print("Ooops, think bigger! ")
    count += 1
else :
    print("Ooops, you dont got it")

else statement block must be executed before the while exits normally. When the while statement is broken, the else statement block will not be executed.

for … else … statement

for i in range(10):
    print("i value = ", i)
    # break 后不会运行 else 块 
else:
    print("success ended")

is similar to while … else …. It will only run when the for statement ends normally. It will not run after break

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