Python’s with statement provides a very convenient way of dealing with the situation where you have to do a setup and teardown to make something happen. A very good example for this is the situation where you want to gain a handler to a file, read da
这一节,我们将学习Python的控制流语句,主要包括if.for.while.break.continue 和pass语句 1. If语句 if语句也许是我们最熟悉的语句.其使用方法如下: x=input("please input an integer:") if x<0: print 'x<0' elif x==0: print 'x=0' elif x>0: print 'x>0' else: print ' x is not an number' 运行
Python’s with statement provides a very convenient way of dealing with the situation where you have to do a setup and teardown to make something happen. A very good example for this is the situation where you want to gain a handler to a file, read da
Python中循环可以使用for语句来实现 list = ['Tom','Lucy','Mary'] for name in list: print(name) 则将会依次输出Tom Lucy Mary 另外Python还支持continue和break关键字,用法与C#相同. 比较有特点的是Python的for语句中支持else关键字 例子: max = 15 for i in range(10): if(i==max): break print(i) else: print('正常/非bre
Python for 循环语句 Python for循环可以遍历任何序列的项目,如一个列表或者一个字符串. 语法: for循环的语法格式如下: for iterating_var in sequence: statements(s) 流程图: 实例: #!/usr/bin/python# -*- coding: UTF-8 -*- for letter in 'Python': # 第一个实例 print '当前字母 :', letter fruits = ['banana',
我们看一个with处理文件操作的实例: with open('/etc/passwd') as f: for line in f: print(line) 这段代码的作用:打开一个文件,如果一切正常,把文件对象赋值给f,然后用迭代器遍历文件中每一行,当完成时,关闭文件: 而无论在这段代码的任何地方,如果发生异常,此时文件仍会被关闭. with看起来如此简单,但是其背后还有一些工作要做,因为你不能对Python的任意对象使用with语句,它仅能工作于支持上下文管理协议(context manage