Python学习笔记

 1 shoplist = [‘apple‘, ‘mango‘, ‘carrot‘, ‘banana‘]  # 声明
 2 
 3 len(shoplist)
 4 
 5 for item in shoplist:
 6     print item
 7 
 8 shoplist.append(‘rice‘)
 9 
10 shoplist.sort()
11 
12 olditem = shoplist[0] 
13 del shoplist[0]  #del的是shoplist[0],不是olditem（下一句还要用）
14 print ‘I bought the‘, olditem

1 #!/usr/bin/python
2 # Filename: print_tuple.py
3 
4 age = 22
5 name = ‘Swaroop‘
6 
7 print ‘%s is %d years old‘ % (name, age)
8 print ‘Why is %s playing with that python?‘ % name

 1 #!/usr/bin/python
 2 # Filename: using_dict.py
 3 
 4 # ‘ab‘ is short for ‘a‘ddress‘b‘ook
 5 
 6 ab = {       ‘Swaroop‘   : ‘swaroopch@byteofpython.info‘,
 7              ‘Larry‘     : ‘larry@wall.org‘,
 8              ‘Matsumoto‘ : ‘matz@ruby-lang.org‘,
 9              ‘Spammer‘   : ‘spammer@hotmail.com‘
10      }
11 
12 print "Swaroop‘s address is %s" % ab[‘Swaroop‘]
13 
14 # Adding a key/value pair
15 ab[‘Guido‘] = ‘guido@python.org‘
16 
17 # Deleting a key/value pair
18 del ab[‘Spammer‘]
19 
20 print ‘\nThere are %d contacts in the address-book\n‘ % len(ab)
21 for name, address in ab.items():
22     print ‘Contact %s at %s‘ % (name, address)
23 
24 if ‘Guido‘ in ab: # OR ab.has_key(‘Guido‘)
25     print "\nGuido‘s address is %s" % ab[‘Guido‘]

1 shoplist = [‘apple‘, ‘mango‘, ‘carrot‘, ‘banana‘]
2 
3 # Indexing or ‘Subscription‘ operation
4 print ‘Item 0 is‘, shoplist[0] 
5 print ‘Item -1 is‘, shoplist[-1]
6 #输出
7 #Item 0 is apple
8 #Item -1 is banana

 1 # Slicing on a list，接上面
 2 print ‘Item 1 to 3 is‘, shoplist[1:3] 
 3 print ‘Item 2 to end is‘, shoplist[2:]
 4 print ‘Item 1 to -1 is‘, shoplist[1:-1]
 5 print ‘Item start to end is‘, shoplist[:]
 6 #输出
 7 #Item 1 to 3 is [‘mango‘, ‘carrot‘]
 8 #Item 2 to end is [‘carrot‘, ‘banana‘]
 9 #Item 1 to -1 is [‘mango‘, ‘carrot‘]
10 #Item start to end is [‘apple‘, ‘mango‘, ‘carrot‘, ‘banana‘]
11 
12 # Slicing on a string
13 name = ‘swaroop‘
14 print ‘characters 1 to 3 is‘, name[1:3]
15 #输出
16 #characters 1 to 3 is wa

 1 #!/usr/bin/python
 2 # Filename: reference.py
 3 
 4 print ‘Simple Assignment‘
 5 shoplist = [‘apple‘, ‘mango‘, ‘carrot‘, ‘banana‘]
 6 mylist = shoplist # mylist is just another name pointing to the same object!
 7 
 8 del shoplist[0]
 9 
10 print ‘shoplist is‘, shoplist
11 print ‘mylist is‘, mylist
12 # notice that both shoplist and mylist both print the same list without
13 # the ‘apple‘ confirming that they point to the same object
14 #输出
15 #Simple Assignment
16 #shoplist is [‘mango‘, ‘carrot‘, ‘banana‘]
17 #mylist is [‘mango‘, ‘carrot‘, ‘banana‘]
18 
19 
20 print ‘Copy by making a full slice‘
21 mylist = shoplist[:] # make a copy by doing a full slice
22 del mylist[0] # remove first item
23 
24 print ‘shoplist is‘, shoplist
25 print ‘mylist is‘, mylist
26 # notice that now the two lists are different
27 #输出
28 #Copy by making a full slice
29 #shoplist is [‘mango‘, ‘carrot‘, ‘banana‘]
30 #mylist is [‘carrot‘, ‘banana‘]

 1 name = ‘Swaroop‘ # This is a string object 
 2 
 3 if name.startswith(‘Swa‘):
 4     print ‘Yes, the string starts with "Swa"‘
 5 
 6 if ‘a‘ in name:
 7     print ‘Yes, it contains the string "a"‘
 8 
 9 if name.find(‘war‘) != -1:
10     print ‘Yes, it contains the string "war"‘
11 
12 delimiter = ‘_*_‘
13 mylist = [‘Brazil‘, ‘Russia‘, ‘India‘, ‘China‘]
14 print delimiter.join(mylist)  #输出Brazil_*_Russia_*_India_*_China

 1 #!/usr/bin/python
 2 # Filename: class_init.py
 3 
 4 class Person:
 5     def __init__(self, name):
 6         self.name = name
 7     def sayHi(self):
 8         print ‘Hello, my name is‘, self.name
 9 
10 p = Person(‘Swaroop‘)  # 注意这里
11 p.sayHi()

 1 #!/usr/bin/python
 2 # Filename: objvar.py
 3 
 4 class Person:
 5     ‘‘‘Represents a person.‘‘‘
 6     population = 0
 7 
 8     def __init__(self, name):
 9         ‘‘‘Initializes the person‘s data.‘‘‘
10         self.name = name
11         print ‘(Initializing %s)‘ % self.name
12 
13         # When this person is created, he/she
14         # adds to the population
15         Person.population += 1
16 
17     def __del__(self):
18         ‘‘‘I am dying.‘‘‘
19         print ‘%s says bye.‘ % self.name
20 
21         Person.population -= 1
22 
23         if Person.population == 0:
24             print ‘I am the last one.‘
25         else:
26             print ‘There are still %d people left.‘ % Person.population
27 
28     def sayHi(self):
29         ‘‘‘Greeting by the person.
30 
31         Really, that‘s all it does.‘‘‘
32         print ‘Hi, my name is %s.‘ % self.name
33 
34     def howMany(self):
35         ‘‘‘Prints the current population.‘‘‘
36         if Person.population == 1:
37             print ‘I am the only person here.‘
38         else:
39             print ‘We have %d persons here.‘ % Person.population
40 
41 swaroop = Person(‘Swaroop‘)
42 swaroop.sayHi()
43 swaroop.howMany()
44 
45 kalam = Person(‘Abdul Kalam‘)
46 kalam.sayHi()
47 kalam.howMany()
48 
49 swaroop.sayHi()
50 swaroop.howMany()

 1 $ python objvar.py
 2 (Initializing Swaroop)
 3 Hi, my name is Swaroop.
 4 I am the only person here.
 5 (Initializing Abdul Kalam)
 6 Hi, my name is Abdul Kalam.
 7 We have 2 persons here.
 8 Hi, my name is Swaroop.
 9 We have 2 persons here.
10 Abdul Kalam says bye.
11 There are still 1 people left.
12 Swaroop says bye.
13 I am the last one.

 1 #!/usr/bin/python
 2 # Filename: inherit.py
 3 
 4 class SchoolMember:
 5     ‘‘‘Represents any school member.‘‘‘
 6     def __init__(self, name, age):
 7         self.name = name
 8         self.age = age
 9         print ‘(Initialized SchoolMember: %s)‘ % self.name
10 
11     def tell(self):
12         ‘‘‘Tell my details.‘‘‘
13         print ‘Name:"%s" Age:"%s"‘ % (self.name, self.age),
14 
15 class Teacher(SchoolMember):
16     ‘‘‘Represents a teacher.‘‘‘
17     def __init__(self, name, age, salary):
18         SchoolMember.__init__(self, name, age)
19         self.salary = salary
20         print ‘(Initialized Teacher: %s)‘ % self.name
21 
22     def tell(self):
23         SchoolMember.tell(self)
24         print ‘Salary: "%d"‘ % self.salary
25 
26 t = Teacher(‘Mrs. Shrividya‘, 40, 30000)

 1 f = file(‘poem.txt‘, ‘w‘) # open for ‘w‘riting
 2 f.write(poem) # write text to file
 3 f.close() # close the file
 4 
 5 f = file(‘poem.txt‘)
 6 # if no mode is specified, ‘r‘ead mode is assumed by default
 7 while True:
 8     line = f.readline()
 9     if len(line) == 0: # Zero length indicates EOF
10         break
11     print line,
12     # Notice comma to avoid automatic newline added by Python
13 f.close() # close the file