#!user/bin/env python
#-*- coding:utf-8 -*-
# code001
print('hello world') (only one quotation mark, but not two on the upper)
# code002
print('''
this is a multi-line string
and this is the first line.
"what's your name?," I asked
He said "Bond, James Bond."
''')
# code003 formatting method
age = 25
name = 'Yuyukun'
print('{0} was {1} years old when he read this book'.format(name,age))
print('why is {0} playing with this python, he loves it?'.format(name))
# code004 concatenate strings, which are derived from code003
age = 25
name = 'Yuyukun'
string1 = name + ' is ' + str(age) + ' years old '
print(string1)
# code005 there is nothing in the brace, i can get a same result with code003
age = 25
name = 'Yuyukun'
print('{} was {} years old when he read this book'.format(name,age))
print('{} playing with this python, he loves it.'.format(name))
# code006 formatting methon(in details)
print('{0:.3f}'.format(1.0/3)) #keep 3 decimal places
print('{0:_^11}'.format('hello')) #11bits and some bits are replaced by letters
print('{name} wrote {book}'.format(name='Lebron', book='shooting star'))
# code007
# 'end' is to avoid line breakprint('a', end='')print('b', end='')
# code008 add a blank in single quotes
print('a', end=' ')
print('b', end=' ')
print('c', end=' ')
# code009 joint mark and line break
# print('this is the first line\nthis is the second line') #'\n':restart a new line
print("this is the first sentence. \
this is the second sentence.") #'\' help people continue inputting data rather than restart a new line
print('r"Newlines are indicated by \n"')
# code010 using varialbe value and invariable value
i = 5
print(i)
i+=1
print(i)
s = '''this is a multi-line string.\
this isthe second line''' #when '\' is located at the end, it represents not line break, but go on.
v = '''this is a multi-line string.\this is the second line''' #when '\' is located at the middle, it is same with a 'Tab'
print(s) #there is a line break in default for the function of 'print()'
print(v)
# code011 normally, there is no semicolon in a sentence in python, cos it has been omitted
i = 5
print(i)
i = 5; print(i);
i = 5; print(i);
i = 5;print(i)
#a same value is output by these methods/
#code012 control flow(if-elif-(elif如果有)-else)
num = 23
guess = int(input('Enter an integer : '))
if guess == num:
print('Congratulations, you guessed it.')
print('(but you do not win any prizes!)')
elif guess > num:
print('No, it is a little lower than that')
else:
print('No, it is a little higher than that')
print('Done')
# code013 control flow(while-else)
# num = 23
# running = True
while running:
guess = int(input('Enter an integer : '))
if guess == num:
print('Congratulations, you guessed it.')
running = False
elif guess < num:
print('No, it is a little higher than that.')
else:
print('No, it is a little lower than that.')
else:
print('The while loop is over.')
print('Done')
# code014 control flow(for-else)
for i in range(1, 5):
print(i)
else:
print('The for loop is over')
# code015 control flow(break)
while True:
s = input('Enter something >>>')
if s == 'quit':
break
print('Length of the string is', len(s))
print('Done')
# code016 control flow(continue)
while True:
s = input('Enter something : ')
if s =='quit':
break
if len(s)<3:
print('the length is too small')
continue
print('Input is of sufficient length')
# code017 Functions(invoking function)
def say_hello():
print('hello world')
say_hello()
say_hello()
# code018 Functions(parameters and arguments)
def print_max(a,b):
if a > b:
print(a, 'is maximum')
elif a == b:
print(a, 'is equal to b')
else:
print(b, 'is maximum')
print_max(3,4)
x=5
y=7
print_max(x,y)
# code019 Functions(parameters and arguments)
x = 50
def func(x):
print('x is', x)
x = 2
print('changed local x to', x)
func(x)
print('x is still', x)
# code020 global parameters
x = 50
def func():
global x
print('x is', x)
x = 2
print('changed global x to', x)
func()
print('value of x to', x)
#code021 function default
def say(message, times=1):
print(message * times)
say('hello')
say('hello', 5)
# code022 function keywords
def func(a, b=5, c=10):
print('a is', a, 'and b is', b, 'and c is', c)
func(3, 7)
func(25, c=24)
func(c=50, a=100)
# code023 function varargs, tuple
def total(a=5, *numbers, **phonebook):
print('a',a)
for single_item in numbers:
print('single_item',single_item) #tuple
for first_part, second_part in phonebook.items():
print(first_part,second_part) #dic
print(total(10,1,2,3,Jack=1123,John=2231,Inge=1560))
# code024 function of return
def maximum(x, y):
if x > y:
return x
if x==y:
return 'the numbers are equal'
else:
return y
print(maximum(3, 3))
# code025 docstrings
# 该文档字符串所约定的是一串多行字符串，其中第一行以某一大写字母开始，以句号结束。
# 第二行为空行，后跟的第三行开始是任何详细的解释说明
#编写的所有重要的函数配以文档字符串
def print_max(x, y):
'''打印这两个数的最大数。
这两个数都应该是整数。'''
x = int(x)
y = int(y)
if x > y:
print(x, 'is maximum')
else:
print(y, 'is miximum')
print_max(3, 5)
print(print_max.__doc__)
result:
# 5 is miximum
# 打印这两个数的最大数。
# 这两个数都应该是整数。
# code026 docstrings
def print_max(x, y):
help(print_max)
'''打印这两个数的最大数。
这两个数都应该是整数。'''
x = int(x)
y = int(y)
if x > y:
print(x, 'is maximum')
else:
print(y, 'is miximum')
print_max(3, 5)
print(print_max.__doc__)
# code027 modules and import operation
import sys
print('The command line arguments are:')
for i in sys.argv: #sys.argv[0], sys.argv[1]... if there are some other arguments
print(i) #print these arguments
print('\n\nThe PYTHONPATH is', sys.path, '\n') #list all directories in which sys.path is located.
# code028 obtain the path of the current precedure
import os;
print(os.getcwd())
# code029 from...import...
from math import sqrt
print("Square root of 16 is", sqrt(16))
if __name__ == '__main__':
print('This program is being run by itself')
else:
print('I am being imported from another module')
# code030 import
import mymodule
mymodule.say_hi()
print('Version', mymodule.__version__)
# lower sentences are stored in the mymodule.py(C:/Users/Administrator.PC-20160817HMOW/PycharmProjects/a byte of python/a byte of python.py)
def say_hi():
print('Hi, this is mymodule speaking')
__version__ = '1'
import mymodule
mymodule.say_hi()
print('My version is ', mymodule.myversion)
# function, module is to call different procedures.
# packages are to organize the structure of procedures
# code031 ds_using_list
shoplist = ['apple', 'mango', 'carrot', 'banana']
print('I have', len(shoplist), 'items to purchase.')
print('these items are:', end=' ')
for item in shoplist:
print(item, end=' ')
print('\nI also have to buy rice.')
shoplist.append('rice')
print('my shopping list is now', shoplist)
print('i will sort my list now')
shoplist.sort()
print('sorted shopping list is', shoplist[0])
olditem = shoplist[0]
del shoplist[0]
print('i bought the', olditem)
print('i bought list is now',shoplist)
# code032 tuple is also a alignment
zoo = ('python', 'elephant', 'penguin')
print('Number of animals in the zoo is', len(zoo))
new_zoo = 'monkey', 'camel', zoo
print('Number of cages in the new_zoo is', len(new_zoo))
print('All animals in new_zoo are', new_zoo)
print('animals brought from old zoo are', zoo)
print('last animal brought from old zoo is', new_zoo[2][2])
print('number of animals in the new zoo is', len(new_zoo)-1+len(new_zoo[2]))
# code033 dict
ab = {
'Swaroop': 'swaroop@swaroopch.com',
'Larry': 'larry@wall.org',
'Matsumoto': 'matz@ruby-lang.org',
'Spammer': 'spammer@hotmail.com',
'Guido' : 'guido@python.org'
}
print("Swaroop's address is", ab['Swaroop'])
del ab['Spammer']
print('\nThere are {} contacts in the address.book\n'.format(len(ab)))
for name, address in ab.items():
print('Contact {} at {}'.format(name, address))
ab['Guido'] = 'guido@python.org'
if 'Guidio' in ab:
print("\nGuido's address is", ab['Guido'])
# code034 sequence
shoplist = ['apple', 'mango', 'carrot', 'banana']
name = 'swaroop'
print('item 0 is', shoplist[0])
print('item 1 is', shoplist[1])
print('item 2 is', shoplist[2])
print('item 3 is', shoplist[3])
print('item -1 is', shoplist[-1])
print('item -2 is', shoplist[-2])
print('Character 0 is', name[0])
print('item 1 to 3 is', shoplist[1:3])
print('item 2 to end is', shoplist[2:])
print('item 1 to -1 is', shoplist[1:-1])
print('item start to end is', shoplist[:])
print('item 1 to 3 is', name[1:3])
print('item 2 to end is', name[2:])
print('item 1 to -1', name[1:-1])
print('characters start to end is', name[:])
# code035 reference comparision between copyscript and slice
print('simple assignment')
shoplist = ['apple', 'mango', 'carrot', 'banana']
mylist = shoplist
del shoplist[0]
print('shoplist is', shoplist)
print('mylist is', mylist)
del mylist[0]
print('shoplist is', shoplist)
print('mylist is', mylist)
print('copy by making a full slice')
mylist = shoplist[:]
del mylist[0]
print('shoplist is', shoplist)
print('mylist is', mylist)
# code035 other strings
name = 'swaroop'
if name.startswith('swa'):
print('yes, the string starts with "swa"')
if 'a' in name:
print('yes, it contains the string "a"')
if name.find('war') == 1:
print('yes, it contains the string "war"')
delimiter = '_*_'
space = ' '
mylist = ['brazil', 'russia', 'india', 'china']
print(delimiter.join(mylist))
print(space.join(mylist))
print(mylist)
# code036 solve problems create a zipfile
import os
import time
source = ['/Users/swa/notes']
target_dir = '/Users/swa/backup'
target = target_dir + os.sep + \
time.strftime('%Y%m%d%H%M%S') + 'zip'
if not os.path.exists(target_dir):
os.mkdir(target_dir)
zip_command = 'zip -r {0} {1}'.format(target,
' '.join(source))
print('zip command is:')
print(zip_command)
print('Running:')
if os.system(zip_command) == 0:
print('Successful backup to', target)
else:
print('Backup Failed')
# code037 class_1
class Person:
pass
p = Person()
print(p)
# code038 class_self
class Person:
def say_hi(self):
print('hello, how are you?')
p = Person()
p.say_hi()
# code039 __init__ implucitly to involk function
class Person:
def __init__(self, name):
self.name = name
def say_hi(self):
print('hello, my name is', self.name)
p = Person('swaroop')
p.say_hi()
# code 040 obejvar
class Robot:
"""表示有一个带有名字的机器人"""
population = 0
def __init__(self, name):
self.name = name
print("(Initializing {})".format(self.name))
Robot.population +=1
def die(self):
print("{} is being destroyed!".format(self.name))
Robot.population -= 1 #Robot.population 类变量
if Robot.population == 0:
print("{} was the last one.".format(self.name))
else:
print("there are still {:d} robots working.".format(Robot.population))
def say_hi(self):
print("Greetings, my masters call me {}".format(self.name))
@classmethod
def how_many(cls):
"""打印出当前的人口数量"""
print("we have {:d} robots.".format(cls.population)) #cls.population 类方法
droid1 = Robot("R2-D2")
droid1.say_hi()
droid1.how_many()
droid2 = Robot("C-3P0")
droid2.say_hi()
droid2.how_many()
print("\nRobots can do some work here.\n")
print("Robots have finished their work. So let's destroy them.")
droid1.die()
droid2.die()
Robot.how_many()
# code 041 subclass
class SchoolMember:
'''代表任何学校里的成员'''
def __init__(self, name, age):
self.name = name
self.age = age
print('(Initialized SchoolMember: {})'.format(self.name))
def tell(self):
print('Name:"{}" Age:"{}"'.format(self.name, self.age), end=" ") #end=" " 不换行并且空一格
class Teacher(SchoolMember):
'''代表一位老师'''
def __init__(self, name, age, salary):
SchoolMember.__init__(self, name, age)
self.salary = salary
print('(Initialized Teacher: {})'.format(self.name))
def tell(self):
SchoolMember.tell(self)
print('Salary: "{:d}"'.format(self.salary))
class Student(SchoolMember):
'''代表一位学生'''
def __init__(self, name, age, marks):
SchoolMember.__init__(self, name, age)
self.marks = marks
print(('Initialized Student: {}').format(self.name))
def tell(self):
SchoolMember.tell(self)
print('Marks: "{:d}"'.format(self.marks))
t = Teacher('Mrs. Shrividya', 40, 30000)
s = Student('Swaroop', 25, 75)
# 打印一行空白行
print()
members = [t,s]
for member in members:
member.tell()
# code 042 input
def reverse(text):
return text[::-1] #逆向输出所有字符
def is_palindrome(text):
return text == reverse(text) #判断是否是palindrome字符
something = input("Enter text: ")
if is_palindrome(something):
print("Yes, it is a palindrome")
else:
print("No, it is not a palindrome")
# code 043 input_exercise
def reverse(text):
return text[::-1] #逆向输出所有字符
def is_palindrome(text):
return text == reverse(text) #判断是否是palindrome字符
something = input("Enter text: ")
if is_palindrome(something):
print("Yes, it is a palindrome")
else:
print("No, it is not a palindrome")
# code044 using_file
poem = '''\
Programming is fun
when the work is done
if you wanna make your work also fun:
use python!
'''
#打开文件以编辑
f = open('poem.txt','w')
#向文件中编写文本
f.write(poem)
#关闭文件
f.close()
#如果没有特别指定，嘉定启用默认的阅读（‘r’ead模式）
f = open('poem.txt')
while True:
line = f.readline()
#零长度指示EOF
if len(line) == 0:
break
#每行('line')的末尾
#都有换行符
#因它是从一个文件中进行读取的
print(line, end='')
#关闭文件
f.close()
help(open)
# code 045 pickle.py
import pickle
#我们存储相关对象的文件的名称
shoplistfile = 'shoplist.data'
#需要购买的物品清单
shoplist = ['apple', 'mango', 'carrot']
#准备写入文件
f = open(shoplistfile, 'wb')
#转移对象至文件
pickle.dump(shoplist, f)
f.close()
#清除shoplist 变量
del shoplist
#重新打开存储文件
f = open(shoplistfile, 'rb')
#从文件中载入对象
storedlist = pickle.load(f)
print(storedlist)
# code046 unicode
import io
f = io.open("abc.txt", "wt", encoding="utf-8") #io.open()指明目前正在使用utf-8
f.write(u"Imagine non-English language here")
f.close()
text = io.open("abc.txt", encoding="utf-8").read()
print(text)
import io
f = io.open("abc.txt", "wt", encoding="utf-8")
f.write(u"Imagine non-English language here")
f.close()
text = io.open("abc.txt", encoding="utf-8").read()
print(text)
import io
f = io.open("abc.txt", "wt", encoding=utf-8)
f.write(u"Imagine non-English language here")
f.close()
text = io.open("abc.txt",encoding="utf-8").read()
print(text)
s = ''
while 1:
t = input("go on(g) or quit(q)\n")
if t != 'q':
name = input('')
pwd = input('')
email = input('')
if len(name) > 20:
name = name[0:20]
if len(pwd) > 20:
pwd = pwd[0:20]
if len(email) > 20:
email = email[0:20]
if t == 'q':
print(s.expandtabs(20), end='')
break
temp = "{0}\t{1}\t{2}\n"
v = temp.format(name,pwd,email)
s = s + v
print(s.expandtabs(20),end='')
# code047 exceptions_handle
try:
text = input('Enter something -->')
except EOFError:
print('Why did y do an EOF on me？')
except KeyboardInterrupt:
print('Y cancelled the operation.')
else:
print('y entered {}'.format(text))
# code048 exceptions_raise.py
class shortInputException(Exception):
'''一个由用户定义的异常类'''
def __init__(self, length, atleast):
Exception.__init__(self)
self.length = length
self.atleast = atleast
try:
text = input('Enter something --> ')
if len(text) < 3:
raise ShortInputException(len(text), 3)
except EOFError:
print('Why did y do an EOF on me?')
except ShortInputException as ex:
print(('ShortInputException: The input was ' + '{0} long, expected at least {1}')
.format(ex.length, ex.atleast))
else:
print('No exception was raised.')
# code 049 exceptions_finally
import sys
import time
f = None
try:
f = open("poem.txt")
while True:
line = f.readline()
if len(line) == 0:
break
print(line, end='')
sys.stdout.flush()
print("Press ctrl+c now")
time.sleep(2)
except IOError:
print("Could not find file poem.txt")
except KeyboardInterrupt:
print("!! You cancelled the reading from the file")
finally:
if f:
f.close()
print("(Cleaning up: Closed the file)")
# code050 exceptions_using_with
# with 语句会在代码块开始之前调用 thefile.__enter__ 函数，并且总会在代码块执行完毕之后调
# 用 thefile.__exit__
with open("poem.txt") as f:
for line in f:
print(line, end='')
