Python 学习笔记10 循环语句 For in
For in 循环主要适用于遍历一个对象中的所有元素。我们可以使用它遍历列表,元组和字典等等。
其主要的流程如下:(图片来源于: https://www.yiibai.com/python/python_for_loop.html)
使用For遍历一个列表:
peoples = ['Ralf', 'Clark', 'Leon', 'Terry'] for people in peoples: print(people) ''' 输出: Ralf Clark Leon Terry '''
使用For in 遍历一个字典:
ralf = {'name': 'Ralf', 'sex': 'male', 'height': '188'} for key, value in ralf.items(): print(key + ":" + value) ''' 输出: name:Ralf sex:male height:188 '''
在For 循环中,我们可以使用 break, 在遇到特殊条件时,中断循环操作:
peoples = ['Ralf', 'Clark', 'Leon', 'Terry', 'Mary'] for people in peoples: if people == 'Terry': break print(people) ''' 输出: Ralf Clark Leon '''
使用continue在for中继后继续下一轮的循环。
peoples = ['Ralf', 'Clark', 'Leon', 'Terry', 'Mary'] for people in peoples: if people == 'Terry': continue print(people) ''' 输出: Ralf Clark Leon Mary '''
For 循环中也可以使用else结构,当循环结束时执行特定语句,但是break中断时,else里面数据不会被执行:
peoples = ['Ralf', 'Clark', 'Leon', 'Terry', 'Mary'] for people in peoples: print(people) else: print('Loop is end') ''' 输出: Ralf Clark Leon Terry Mary Loop is end ''' peoples = ['Ralf', 'Clark', 'Leon', 'Terry', 'Mary'] for people in peoples: if people == 'Terry': break print(people) else: print('Loop is end') ''' 输出: Ralf Clark Leon '''