Python入门教程-13 for-in

1. 循环

for-in是Python中表示循环的其中一种方法。

2. 基本语法

示例：

>>> values = ['first', 'second', 'third']>>> for value in values:...     print value...firstsecondthird>>>

for循环对于列表中的数据类型是不关注的，比如list存放的是tuple这种类型：

Python 3.4.4 (v3.4.4:737efcadf5a6, Dec 20 2015, 19:28:18) [MSC v.1600 32 bit (Intel)] on win32Type "help", "copyright", "credits" or "license" for more information.>>> values = [('Tom', 23), ('John', 18), ('Ann', 20)]>>> for value in values:...     name, age = value...     info = "name=%s, age=%d" % (name, age)...     print(info) # in Python 3.4...name=Tom, age=23name=John, age=18name=Ann, age=20>>>

3. break和continue

python的循环体中也可以使用break和continue语句，功能和语法和C/C++一样。

>>> items = range(1, 20, 2)>>> items[1, 3, 5, 7, 9, 11, 13, 15, 17, 19]>>> for item in items:...     if item % 3 == 0: pass...     print item...     if item >= 17: break...1357911131517>>>