python学习---第一小节

运行首个程序hello_world.py

#_*_coding:utf-8_*_

print("Hello world!")

输出结果：

Hello world!

变量

#_*_coding:utf-8_*_

name = "beyoungt"

#_*_coding:utf-8_*_

name = "beyoungt"
print(name)

name = “abby"
print(name)

输出结果：

beyoungt
abby

在程序中可随时修改变量的值，python将始终记录变量的最新值。

字符串:

python中，用引号括起来的都是字符串。可以是单引号也可以是双引号。

"This is a string."
‘This is also a string.‘

使用方法修改字符串大小写：

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

输出：

Beyoungt

title():将每个单词首字母改为大写。

upper():将字符串全部改为大写。

lower():将字符串全部改为小写。

字符串的拼接：

first_name = "tian"
last_name = "beyoungt"
full_name = first_name + " " + last_name

print("Hello," + full_name.title+" ! " )

输出：

Hello，Tian Beyoungt!

字符串的格式化输出:

name = “beyoungt"
print("my name is %s" %name)

#输出：my name is beyoungt

%s:字符串    %d:整数    %f:浮点数

name = input("name:")
age = int(input("age:") ) #integer
job = input("job:")
salary  = input("salary:")

info = ‘‘‘
-------- info of  %s  -----
Name:%s
Age:%d
Job:%s
Salary:%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)

添加制表符: \t

添加换行符: \n

print("Languages:\n\tPython\nC\n\tJavaScript")

输出：
Languages:
    Python
C
    JavaScript

删除空白:

favorite_language = "  python  "
favorite_language.rstrip()    #删除末尾空白
favorite_language.lstrip()    #删除开头空白
favorite_language.strip()     #删除两端空白

模块:

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

getpass模块使密码隐藏。

循环：

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

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

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

guess小游戏及改进:

#！usr/bin/env python

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

# Author burnywen 

age_of_burnywen = 23
for 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 = 23

count = 0
while 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 +=1
else:
    print("you have tried too many times.")

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

age_of_buruywen =23

count = 0
while 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 =0
else:
    print("you have tried too many times.")