>>> 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.元组,数组(是个线性结构,可以用整数索引)
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
...
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 documentation import sys import os (3)Module imports debug = True (4)(Global) Variable declarations class 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();
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