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
'''

 

posted @ 2019-04-18 21:08  追风狂想  阅读(707)  评论(0编辑  收藏  举报