《Python基础教程》 读书笔记 第五章（下）循环语句

x=1
while x<=100:
    print x
    x+=1 

name=""
while not name:
    name=raw_input(‘please enter your name:‘)
print ‘hello,%s!‘%name

words=[‘a‘,‘b‘,‘c‘,‘d‘]
for word in words:
    print word

d={‘x‘:1,‘y‘:2,‘z‘:3}
for key in d:
    print key,‘corresponds to‘,d[key]

names=[‘anne‘,‘beth‘,‘george‘,‘damon‘]
ages=[12,45,32,102]
for i  in range(len(names)):
    print names[1],‘is‘,ages[i],‘years old‘

>>> zip(names,ages)
[(‘anne‘, 12), (‘beth‘, 45), (‘george‘, 32), (‘damon‘, 102)]

>>> for name,age in zip(names,ages):

    print name,‘is‘,age,‘years old‘

anne is 12 years old

beth is 45 years old

george is 32 years old

damon is 102 years old

index=0

for string in strings:

    if ‘xxx‘ in strings:

    strings[index]=‘[censored‘

index+=1

>>> sorted([4,3,5,8,1])

[1, 3, 4, 5, 8]

>>> sorted(‘hell,world!‘)

[‘!‘, ‘,‘, ‘d‘, ‘e‘, ‘h‘, ‘l‘, ‘l‘, ‘l‘, ‘o‘, ‘r‘, ‘w‘]

>>> list(reversed(‘hello,world‘))

[‘d‘, ‘l‘, ‘r‘, ‘o‘, ‘w‘, ‘,‘, ‘o‘, ‘l‘, ‘l‘, ‘e‘, ‘h‘]

>>> ‘‘.join(reversed(‘hello,world!‘))

‘!dlrow,olleh‘

from math import sqrt

for n in range(99,0,-1):

    root=sqrt(n)

    if root ==int(root):

        print n

        break

while True:

    word=raw_input(‘please enter a word:‘)

    if not word:break

    print ‘the word was ‘+word

from math import sqrt

for n in range(99,81,-1):

    root=sqrt(n)

    if root==int(root):

        print n

        break

    else:

        print "didn‘t find it"

>>> [x*x for x in range(10)]

[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]

>>> [(x,y)for x in range(3) for y in range(3)]

[(0, 0), (0, 1), (0, 2), (1, 0), (1, 1), (1, 2), (2, 0), (2, 1), (2, 2)

if name==‘ralph‘:
    print ‘welcome!‘
elif name==‘enid‘:
    pass
elif name==‘bill‘:
    print ‘access‘

>>> scoundrel={‘age‘:42,‘first name‘:‘robin‘,‘last name‘:‘of locksley‘}
>>> robin=scoundrel
>>> scoundrel
{‘last name‘: ‘of locksley‘, ‘first name‘: ‘robin‘, ‘age‘: 42}
>>> robin
{‘last name‘: ‘of locksley‘, ‘first name‘: ‘robin‘, ‘age‘: 42}
>>> coundrel=None
>>> robin
{‘last name‘: ‘of locksley‘, ‘first name‘: ‘robin‘, ‘age‘: 42}
>>> robin=None

>>> x=["hello","world"]
>>> y=x
>>> y[1]="python"
>>> x
[‘hello‘, ‘python‘]
>>> del x
>>> y
[‘hello‘, ‘python‘]
>>> x
Traceback (most recent call last):
  File "<input>", line 1, in <module>
NameError: name ‘x‘ is not defined

>>> exec "print ‘hello,world!‘"
hello,world!

>>> from math import sqrt
>>> exec "sqrt=1"
>>> sqrt(4)
Traceback (most recent call last):
  File "<input>", line 1, in <module>
TypeError: ‘int‘ object is not callable

>>> from math import sqrt
>>> scope={}
>>> exec "sqrt=1" in scope
>>> sqrt(4)
2.0
>>> scope[‘sqrt‘]
1

>>> len(scope)
2
>>> scope.keys()
[‘__builtins__‘, ‘sqrt‘]

>>> eval(raw_input("enter an arthmetric expression:"))
enter an arthmetric expression: 6+18*2
42