Python: start up

python_start_up.py

#!/usr/bin/python

# This is a start up list for python
# It will be used to quickly review the basic syntaxes and operations of python
# Code summerized from "简明 Python 教程" : http://woodpecker.org.cn/abyteofpython_cn/chinese/index.html

# Usually, python command options begin with two -- , e.g.  --version --help

# Python Use True & False for boolean values

# None for null

# Control block

if a == b:
    #do somethings…
elif a > b:
    #do somethings else …
else:
    #end.

while a != b:
    #do something

#functions
def sayHello(message, time = 1):
    # instructions here
    print message * times

#doc
def max(a,b):
    '''Find the maximum of two numbers: function title

    The two numbers must be integer : function description'''
    # do somethings...
    pass

#module: a file that contains all the variables and functions 
import sys
for i in sys.argv:
     print i # print input params

#data structure:
#list: [1, 2, 3, 4, 5]  #can store data with any type
l =  [1, 2, 3, 4, 5]
len(list) # length of list
list.append("last one")  # add item in the end
del list[0] = list.remove(0)  #remove item 0

#tuple : unmutable list, usually used for print
t = ('cat', 'dog', 'wolf')
print t[0]
print "The age for %s is %s" % (name, age)

# dictionary
ab = {}
ab['Guido'] = 'guido@python.org'
for name, address in ab.items():
    print 'Contact %s at %s' % (name, address)

if 'Guido' in ab: # OR ab.has_key('Guido')
    print "\nGuido's address is %s" % ab['guido']

# string functions:
name = 'Swaroop' # This is a string object 
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 = '_*_'
mylist = ['Brazil', 'Russia', 'India', 'China']
print delimiter.join(mylist)

#oop: 
#类的方法必须有一个额外的参数名称self， 调用时候python会自动赋值！！
class Person:    

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

    def sayHi(self):
        print 'Hello, my name is', self.name

p = Person('Swaroop')
p.sayHi()

# inheritance:
class Teacher(SchoolMember):    '''Represents a teacher.'''

    def __init__(self, name, age, salary):

        SchoolMember.__init__(self, name, age)

        self.salary = salary
        print '(Initialized Teacher: %s)' % self.name

# exception handling: try.. except..
import sys
try:
    s = raw_input('Enter something --> ')
except EOFError:
    print '\nWhy did you do an EOF on me?'
    sys.exit() # exit the program

#在函数中接收元组和列表
def powersum(power, *args):     
    '''Return the sum of each argument raised to specified power.'''
    total = 0
    for i in args:
        total += pow(i, power)
    return total

powersum(2, 3, 4) # will return 25


#execute shell command：
os.system(zip_command)


#determine if file exists
if not os.path.exists(file_dir):
    os.mkdir(file_dir) # make directory


# basic file handing:
poem = '''\
Programming is fun
When the work is done
if you wanna make your work also fun:
        use Python!'''

f = file('poem.txt', 'w') # open for 'w'riting
f.write(poem) # write text to file
f.close() # close the file

f = file('poem.txt')
# if no mode is specified, 'r'ead mode is assumed by default
while True:
    line = f.readline()
    if len(line) == 0: # Zero length indicates EOF
        break
    print line,
    # Notice comma to avoid automatic newline added by Python
f.close() # close the file