Core Python Programming筆記,Note

>>> logfile=open('/tmp/mylog.txt','a')

>>> print >> logfile, 'fatail error: invalid arguments'

>>> logfile.close()

>>>

user=raw_input("please input your name:")

Numbers:

int

long

bool(True,False)

float

complex(6.23+1.5j)

tuple

1.元組,數組(是個線性結構,可以用整數索引)

Lists [] and Tuples (): 

hold any arbitrary number of arbitrary Python objects, the items are ordered

and accessed via index offsets, similar to arrays, except that lists and tuples can store 

different types of objects.

Tuples can be thought of for now as "read-only" lists.

Subsets can be taken with the slice operator ([] and [:]) in the same manner as strings.

Dictionaries

Dictionaries (or "dicts for short) are Python's mapping type and work like associative arrays

or hashes found in perl.

>>> aDict = {'host':'earth'}

>>> aDict

{'host': 'earth'}

>>> aDict['port']=8080

>>> aDict

{'host': 'earth', 'port': 8080}

>>> aDict.keys()

['host', 'port']

>>> for key in aDict:

...     print key, aDict[key]

...

host earth

port 8080

if expression1:

if_suite

elif expression2:

elif_suite

else:

else_suite

>>> while cnt<3:

...     print 'loop %d'%(cnt)

...     cnt+=1

...

loop 0

loop 1

loop 2

>>> for item in range(10):

...     print item

>>> for item in ['e-mail','net-surfing','homework']:

...     print item

...

e-mail

net-surfing

homework

List Comprehensions:

>>> squared = [x**2 for x in range(4)]

>>> squared

[0, 1, 4, 9]

>>> for i in [x**2 for x in range(6)]:

...     print i

...

0

1

4

9

16

25

Useful Built-In Functions for New Python Programmers

dir([obj]),help([obj]),int(obj),len(obj),open(fn,mode),range([start,]stop[,step]),

rraw_input(str),str(obj),type(obj)

Typical Python file structure

#!/usr/bin/env python(1)Startup line (Unix)"this is a test module"(2)Module documentationimport sysimport os(3)Module importsdebug = True(4)(Global) Variable declarationsclass FooClass (object):"Foo class"pass(5)Class declarations (if any)def test():"test function"foo = FooClass()if debug:print 'run test()'(6)Funcation declarations(if any)if __name__ == '__main__':test();

　　

P 115 / 1155