冯唐--python学习日记(5)

例程：

>>> import random
>>> import sys
>>> SecretNumber= random.randint(1,100)
>>> print "i'm thinking of a number between 1 to 100"
i'm thinking of a number between 1 to 100
>>> while(1):
 print "Guess my number."
 NumberGuess = int(sys.stdin.readline())
 if (NumberGuess == SecretNumber):
  print "Correct! Choosing a new number..."
  SecretNumber = random.randint(1,100)
 elif (NumberGuess > SecretNumber):
  print "lower."
 else:
  print "Eigher."

Guess my number.
9
Eigher.
Guess my number.
5
Eigher.
Guess my number.
99
lower.
Guess my number.
56
Eigher.
Guess my number.
77
Eigher.
Guess my number.
88
Eigher.
Guess my number.
95
lower.
Guess my number.
90
Correct! Choosing a new number...
Guess my number.
90
Eigher.
Guess my number.
95
lower.
Guess my number.
95
lower.
Guess my number.
93
lower.
Guess my number.
91
Correct! Choosing a new number...
Guess my number.
92
lower.
Guess my number.
80
Eigher.
Guess my number.
86
lower.
Guess my number.
5
Eigher.
Guess my number.
85
Correct! Choosing a new number...
Guess my number.

一、if语句

if (condition):

       expression

else:

       expression

二、while语句

while (expression):

          if (condition):

                     expression

          elif:

                     expression

          ...

          else:

                    expression

 三、for循环

for in :

      (loop body)

 例

>>> import string
>>> def Encode(MessageString):
 EncodeList = []
 for Char in MessageString:
  EncodeList.append("%x" % ord(Char))
 return EncodeList

>>> def Decode(SecretMessage):
 DecodedList = []
 for hexvalue in SecretMessage:
  DecodedList.append(chr(int(hexvalue,16)))
 return string.join(DecodedList,"")

>>> if (__name__=="__main__"):
 SecretMessage = Encode("remember to drink your Ovaltine!")
 print SecretMessage
 print Decode(SecretMessage)

['72', '65', '6d', '65', '6d', '62', '65', '72', '20', '74', '6f', '20', '64', '72', '69', '6e', '6b', '20', '79', '6f', '75', '72', '20', '4f', '76', '61', '6c', '74', '69', '6e', '65', '21']
remember to drink your Ovaltine!
>>>

中断和继续

continue和break

例打印0～99之间的偶数，循环一次，删除没有处理的序列的第一个数据，打印第二个元素。

>>> MyRange = range(100)
>>> for x in MyRange:
 print x
 del MyRange[0]

错误处理机制

try块和finally块

try块捕捉错误

finally是放置必须执行的代码块

四、利用断言进行调试