Python learning --- chapter 1, python learning --- Section

Python learning --- chapter 1, python learning --- Section

Run the first program hello_world.py

#_*_coding:utf-8_*_print("Hello world!")

Output result:

Hello world!

Variable

#_*_coding:utf-8_*_name = "beyoungt"

 

#_*_coding:utf-8_*_name = "beyoungt"print(name)name = “abby"print(name)

Output result:

beyoungtabby

You can change the value of a variable in a program at any time. python always records the latest value of the variable.

String:

In python, all enclosed in quotation marks are strings. It can be either a single quotation mark or a double quotation mark.

"This is a string."'This is also a string.'

How to modify the case sensitivity of a string:

name = "beyoungt"print(name.title())  

Output:

Beyoungt

Title (): change the first letter of each word to uppercase.

Upper (): converts all strings to uppercase.

Lower (): change all strings to lowercase.

String concatenation:

first_name = "tian"last_name = "beyoungt"full_name = first_name + " " + last_nameprint("Hello," + full_name.title+" ! " )

Output:

Hello，Tian Beyoungt!

 

Formatted output of the string:

Name = "beyoungt" print ("my name is % s" % name) # output: my name is beyoungt

% S: String % d: integer % f: Floating Point

name = input("name:")age = int(input("age:") ) #integerjob = input("job:")salary  = input("salary:")info = '''-------- info of  %s  -----Name:%sAge:%dJob:%sSalary:%s''' % (name,name,age,job,salary)info2 = '''-------- info of {_name}  -----Name:{_name}Age:{_age}Job:{_job}Salary:{_salary}'''.format(_name=name,           _age=age,           _job=job,           _salary=salary)info3 =  '''-------- info of {0} -----Name:{0}Age:{1}Job:{2}Salary:{3}'''.format(name,age,job,salary)print(info3)

Add a tab: \ t

Add line break: \ n

Print ("ages: \ n \ tPython \ nC \ n \ tJavaScript") Output: Ages: PythonC JavaScript

Delete blank:

Favorite_language = "python" favorite_language.rstrip () # Delete blank spaces at the end of favorite_language.lstrip () # Delete blank spaces at the beginning of favorite_language.strip () # Delete blank spaces

 

Module:

#！usr/bin/env python#-*- coding:utf-8-*-# Author burnywenimport getpass_username = 'burnywen'_password = '123456'username = input("username:")#password = getpass.getpass("password:")  #fails to work well in pycharm;password = input("password:")if _username == username and _password == password:    print("Welcome user {name} login...".format(name=username))else:    print("Invalid username or password!")

The getpass module hides the password.

Loop:

#！usr/bin/env python#-*- coding:utf-8-*-# Author burnywencount = 0while True:    print("count:",count)    count +=1    if count == 100:        break

#！usr/bin/env python#-*- coding:utf-8-*-# Author burnywenfor i in range(0,10):    if i <3:        print("loop ",i)    else :        continue    print("oh....")

 

#！usr/bin/env python#-*- coding:utf-8-*-# Author burnywenfor i in range(10):    print('----------',i)    for j in range(10):        print(j)        if j >5:            break

Guess games and improvements:

#！usr/bin/env python

#-*- coding:utf-8-*-

# Author burnywen 

age_of_burnywen = 23for i in range(3):    guess_age = int(input("guess age:") )    if guess_age == age_of_burnywen :        print("congratulations, you are right. ")        break    elif guess_age > age_of_burnywen:        print("think smaller...")    else:        print("think bigger...")else:    print("you have tried too many times.")

 

#！usr/bin/env python#-*- coding:utf-8-*-# Author burnywen

age_of_burnywen = 23count = 0while count <3:    guess_age = int(input("guess age:") )    if guess_age == age_of_burnywen :        print("congratulations, you are ringht. ")        break    elif guess_age > age_of_burnywen:        print("think smaller...")    else:        print("think bigger!")    count +=1else:    print("you have tried too many times.")

 

#！usr/bin/env python#-*- coding:utf-8-*-# Author burnywenage_of_buruywen =23count = 0while count <3:    guess_age = int(input("guess age:") )    if guess_age == age_of_burnywen :        print("congratulations, you are right. ")        break    elif guess_age > age_of_burnywen:        print("think smaller...")    else:        print("think bigger!")    count +=1    if count == 3:        countine_confirm = input("do you want to keep guessing..?")        if countine_confirm != 'n':              count =0else:    print("you have tried too many times.")