python点滴

1、print语句： 
print 'hello world!' 
print "hello world!" 
print 'hello %s!'%('world') 
2、流程控制： 
if: 
a = 1;b = 2 
if (a == b): 
  print 'a = b' 
elif (a > b): 
  print 'a > b' 
elif (a < b): 
  print 'a < b' 
else: 
  print '$%$#$%' 
for each : 
array = [1,2,3,4] 
total = 0 
for i in array: 
  total +=i 
print total 
while: 
while 1 > 2 
  pass 
3、数据类型： 
链表：array=[1,2,3,4] print array  result:[1,2,3,4] 
散列： 
print set ([1,2,3,4,4]) result:set([1,2,3,4]) 
set1 = set([1,2,3,4,5]) set2 = set([1,2,3,4,6]) 
print set1-set2 result:set([5]) 
print set1&set2 result:set([1,2,3,4]) 
print set1|set2 result:set([1,2,3,4,5,6]) 
字典： 
dict = {} 
dict['zs'] = 12 
dict['ls'] = 25 
dict['ww'] = 36 
for key in dict.keys(): 
  print '%s%s'%(key,dict[key])  result:ww36 ls25 zs12 
4、文件读写： 
f = file("d:\work\a.txt","r") 
print f.read() 
f.close() #文件流需关闭 
with open ("d:\work\a.txt","r") as f: 
   print f.read() 
with open ("d:\work\b.txt","w") as f: 
   f.write("i am ok!")