python学习小结1：for循环控制语句

用一个列表来确定for循环的范围

>>> x = [0,1,2,3,4]>>> for i in x:    print i,    0 1 2 3 4

 循环一个字符串

>>> x = 'python'>>> for i in x:    print i,    p y t h o n

 元组for循环

>>> x = [('http','https'),('java','python')]>>> for (a,b) in x:    print (a,b)    ('http', 'https')('java', 'python')

 迭代器

# 文件迭代器，读取文件的最佳实践>>> for line in open('test.txt'):    print line.upper()    HELLO,WORD!# 字典迭代器>>> testDict = {'name':'ethon','aender':'male'}>>> for key in testDict:    print key + ':' + testDict[key]    aender:malename:ethon

 迭代协议：有一些函数可以在支持迭代协议的对象上运行

>>> testList = [9,8,7,6,5]>>> print sorted(testList)[5, 6, 7, 8, 9]>>> print sum(testList)35>>> print any(testList)True>>> print list(open('test.txt'))['Hello,word!']>>> print tuple(open('test.txt'))('Hello,word!',)
# 元组、列表的构造函数以及join都可以对支持迭代协议的对象操作>>> print ('--').join(open('test.txt'))Hello,word!

 使用range函数来产生循环的范围

>>> for i in range(5):    print str(i)+ 'is the current value'    0 is the current value1 is the current value2 is the current value3 is the current value4 is the current value

zip拉链：使用zip函数可以把两个列表合并起来，成为一个元组的列表。

>>> L1 = [1,3,5,7]>>> L2 = [2,4,6,8]>>> print zip(L1,L2)[(1, 2), (3, 4), (5, 6), (7, 8)]>>> for (a,b) in  zip(L1,L2):    print (a,b)    (1, 2)(3, 4)(5, 6)(7, 8)

 可变嵌套循环

ns = int(raw_input("How many lines of starts do you want? "))st = int(raw_input("How many start do you want? "))for line in range(0,ns): # 外循环    for star in range(0,st): # 内循环        print "*",    print

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How many lines of starts do you want? 3
How many start do you want? 5
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