PYTHON第二天笔记
(PYTHON全栈开发)第二天笔记
一、复习第一天内容
1.计算机基本运作
2.为何python
3.变量
4.条件语句
5.循环
6.输入
python2: name = raw_input('请输入用户名:')
python3: name = input('请输入用户名:')
注意⚠️:raw_input输入的内容永远是字符串类型!!!
而input返回的是value。
7.第一天练习题讲解
(1)打印1-99之间的所有奇数
#-*- encoding:utf-8 -*- start = 1 while start < 100: result = start % 2 if result == 1: print(start) start = start +1
(2)打印1-99之间所有被3整除数
#-*- encoding:utf-8 -*- start = 3 while start <= 99: if start % 3 == 0: print(start) start = start +1
(3)打印1-99之间所有数总和
#-*- encoding:utf-8 -*- sum = 0 start = 1 while start < 100: sum = sum + start start = start +1 print(sum)
(4)打印1-99之间所有奇数总和
# -*- encoding:utf-8 -*- sum = 0 start = 1 while start < 100: if start % 2 == 1: sum = sum + start start = start +1 print(sum)
(5)打印1-2+3-4+5...+99总和
# -*- encoding:utf-8 -*- sum = 0 start = 1 while start < 100: if start % 2 == 1: sum = sum + start elif start % 2 == 0: sum = sum - start start = start +1 print(sum)
二、安装pycharm及使用设置
1.默认安装
2.激活http://blog.csdn.net/u013066730/article/details/56966966
http://www.imsxm.com/jetbrains-license-server.html
三、字符串格式化
n1 = input('请输入:') age = input('快输入:') raw_in = "您输入的内容为%s,年龄%s" %(n1,age)
//如果为单个变量,则可去掉括号写为"内容为%s" %n1
print(raw_in)
四、编码和二进制(基础)
ascii码: unicode: utf-8: gbk
ascii: 美国编制最早编码,8位表示一字符
unicode: 全球使用,包含所有国家文字(万国码),弊端:占用太大
utf-8: 代替unicode,全球通用(兼容中文,汉字占3字节)
gbk:中国编码,汉字占2字节
单位换算:
1位 = 1bit
8bit = 1字节 = 1byte
1024字节 = 1kb
1024kb = 1mb
1024mb = 1gb
五、运算符补充
1.除法/中:py2(from __future__ import division)文件头引入后和py3相同。
如不引用,py2:9/2==4,py3:9/2==4.5
2.算数运算:
**:幂-返回x的y次方
//:取整除-返回商的整数部分
3.比较运算:
!=:不等于,符号两方不相等
<>:不等于,符号两方不相等
4.赋值运算:
+=:a = a + 1 <=> a += 1
-=:a = a - 1 <=> a -= 1
5.逻辑运算:
and:布尔“与”,只有两端真为真
or:布尔“或”,两端一真一假为真,两真为真,两假为假
not:布尔“非”,非真为假,非假为真
6.成员运算:
in:在指定序列找到为True,找不到False
not in:在指定序列找不到为True,找到为False