python学习笔记--for循环
推荐一个学习语言的网站:http://www.codecademy.com
有教程,可以边学边写,蛮不错的。
for循环:
1.for
loops allow us to iterate through all of the elements in a list from the left-most (or zeroth element) to the right-most element. A sample loop would be structured as following:
使用for循环可以遍历一个列表,从最左到最右:
a = ["List of some sort”]
for x in a:
# Do something for every x
2.You can also use a
for
loop on a dictionary to loop through its keys with the following:可以使用for循环通过key值去遍历一个字典
webster = {
"Aardvark" : "A star of a popular children's cartoon show.",
"Baa" : "The sound a goat makes.",
"Carpet": "Goes on the floor.",
"Dab": "A small amount."
} # Add your code below!
for key in webster:
print webster[key]
Note that dictionaries are unordered, meaning that any time you loop through a dictionary, you will go through every key, but you are not guaranteed to get them in any particular order.遍历过程是无序的
3.While looping, you may want to perform different actions depending on the particular item in the list. This can be achieved by combining your loops with control flow (if/else
statements) that might resemble the following:
Make sure to keep track of your indentation or you may get confused!可以使用if/else语句去控制for的内容
a = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13] for number in a:
if number % 2 == 0:
print number
4.Functions can also take lists as inputs and perform various operations on those lists.
x = ['fizz','buzz','fizz'] def fizz_count(x):
count = 0
for word in x:
if word == 'fizz':
count = count + 1
return count
5.String Looping:As we've mentioned, strings are like lists with characters as elements. You can loop through strings the same way you loop through lists!字符遍历
for letter in "Codecademy":
print letter # Empty lines to make the output pretty
print word = "Programming is fun!" for letter in word:
# Only print out the letter i
if letter == "i":
print letter
python学习笔记--for循环的更多相关文章
- 【Python学习笔记】循环和迭代
for和while基本语法 break和continue else的使用 enumerate和zip在循环中的应用 for和while基本语法 Python中的的循环使用for和while语句来实现, ...
- python学习笔记:循环语句——while、for
python中有两种循环,while和for,两种循环的区别是,while循环之前,先判断一次,如果满足条件的话,再循环,for循环的时候必须有一个可迭代的对象,才能循环,比如说得有一个数组.循环里面 ...
- Python 学习笔记9 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/pytho ...
- Python 学习笔记8 循环语句 while
While循环是哟中利用条件语句,不断的执行某一段代码块,达到批量操作输出等一系列的操作,直到条件不满足或者被强制退出为止. 其工作流程如下: (图片来源菜鸟教程:http://www.runoob. ...
- python学习笔记四——循环及冒泡排序
3.3.3 break 和 continue语句 break:跳出整个循环 continue:跳出当前循环继续后面的循环 例: x=int(input("please input the ' ...
- python 学习笔记(循环,print的几种写法,操作符)
一.循环( for, while) while循环是指在给定的条件成立时(true),执行循环体,否则退出循环.for循环是指重复执行语句. break 在需要时终止for /while循环 cont ...
- python学习笔记1 循环、列表、元祖、数据类型
if语法:基于python3语法 if a<b: 冒号结尾 print("yes") 注意语句的缩进需要一致,不然会报语法错误. elif a==b: print(" ...
- python学习笔记 - for循环: 遍历字典, 分别打印key, value, key:value
#遍历字典, 分别打印key, value, key:value emp = {'name':'Tom', 'age':20, 'salary' : 8800.00} for k in emp.key ...
- 【python学习笔记】5.条件、循环和其他语句
[python学习笔记]5.条件.循环和其他语句 print: 用来打印表达式,不管是字符串还是其他类型,都输出以字符串输出:可以通过逗号分隔输出多个表达式 import: 导入模块 impo ...
随机推荐
- Codeforces Round #218 (Div. 2)
500pt, 题目链接:http://codeforces.com/problemset/problem/371/A 分析:k-periodic说明每一段长度为k,整个数组被分成这样长度为k的片段,要 ...
- 【ASP.NET Web API教程】4.1 ASP.NET Web API中的路由
原文:[ASP.NET Web API教程]4.1 ASP.NET Web API中的路由 注:本文是[ASP.NET Web API系列教程]的一部分,如果您是第一次看本博客文章,请先看前面的内容. ...
- 卸载QTP
卸载QTP11.5 1.首先需要卸载QTP11.5,点击exe文件,不点击重启 2.然后删除C:"Program Files"下的Mercury Interactive文件夹.(默 ...
- 为cocos2dx添加ndk库
碰到很多坑: 1:引用库定义成include $(BUILD_SHARED_LIBRARY),结果生成了两个so文件,应该把库声明为BUILD_STATIC_LIBRARY 2:把库的java放到了项 ...
- 如何设置lmt的空间警告阀值
Example—设置Locally Managed Tablespace的空间警告阀值 The following example sets the free-space-remaining thre ...
- 14.4.7 Configuring the Number of Background InnoDB IO Threads 配置 后台InnoDB IO Threads的数量
14.4.7 Configuring the Number of Background InnoDB IO Threads 配置 后台InnoDB IO Threads的数量 InnoDB 使用bac ...
- Hbase集群环境搭建
Hbase数据库依赖 Hadoop和zookeeper,所以,安装Hbase之前,需要先把zookeeper集群搭建好.(当然,Hbase有内建的zookeeper,不过不建议使用).Hbase配置上 ...
- SQL Server 数据的添加修改删除和查询
数据的添加: 首先建立一个数据库,点击新建查询,然后用代码建立一个表,表里写上列名和数据类型,约束可加可不加 然后使用insert语句往表里添加数据 insert [into] 表名 (列名1,列名2 ...
- HTML5调用摄像头实现拍照功能(兼容各大主流浏览器)
本人亲測,兼容各大主流浏览器,HTML5太强大了,须要的留下邮箱哦 假设想要立即收到,则可到我的资源下载 http://download.csdn.net/detail/laijieyao/81699 ...
- API - 微云
API - 微云 1.接口说明 2.数据上传协议说明 1. 接口说明 文件上传申请,成功会返回实际上传的地址. 根据申请上传返回的地址,组织数据上传. 1.1 URL OAuth2.0协议: http ...