PYTHON basic

1. 关于has , is.

class Person(object):

    def __init__(self, name):
        ## has name
        self.name = name

        ## Person has-a pet of some kind
        self.pet = None

 
class Employee(Person):

    def __init__(self, name, salary):
         
        super(Employee, self).__init__(name)
        ## emplyee has salary
        self.salary = salary

 2.描述代码发生了什么

   class song has a __init__ that takes self and lyrics parameters.

                      has function named  sing_me_a_song that takes self parameters.

    Set bulls_on_parade to an instance of class Song.

   From bulls_on_parade, get the sing_me_a_song function.

class Song(object):

    def __init__(self, lyrics):
        self.lyrics = lyrics

    def sing_me_a_song(self):
        for line in self.lyrics:
            print(line)

bulls_on_parade = Song(["They rally around tha family",
"With pockets full of shells"])

bulls_on_parade.sing_me_a_song()

 3. 继续描述代码发生了什么

ten_things = "Apples Oranges Crows Telephone Light Sugar"  
# set a string to ten_things.

stuff = ten_things.split(' ')
# Call split with argument ' ' on ten_things, set it to stuff

' '.join(stuff)
# string has a attribute 'join', argument.

stuff.append(next_one)
# Call append with argument next_one on stuff

 

4. python 练习， string

str1 = 'abcefghxyzThis,is,the,target,string xyzlkdjf'
idx1 = str1.find('xyz') # get the position of 'xyz'
idx2 = str1.find( 'xyz' , idx1+1) # get the next 'xyz'
str1 = str1[idx1+3:idx2].replace(',','|' ) # replace ',' with '|'
str1 = str1.strip() # strip trailing spaces.