python-day2

2. 文件形
#/usr/bin/u/ubv/a python

3. 编码
#/usr/bin/u/ubv/a python
# -*- coding:utf-8 -*-
补充：

字节，位
unicode utf8 gbk
utf8: 3
gbk : 2

4. print("sdf")

5. inp = input('>>>')

PS:
>>> hello
inp = "hello"

>>> 10
inp = "10"

# 如果将字符串转换成数字 new_inp = int(inp)

inp * 10 =?????

6. 变量名

要求：
不能数字开头
不能使用关键字
建议不要用python内置的。。。。

7. 条件语句
1. 基本
2. 嵌套
3. if elif else ...

8. while循环
while 条件：
....

print('...')

补充：
a. while else
b. continue break
continue ,终止当前循环，开始下一次循环
break ,终止所有循环

用户登陆（三次机会重试）
count = 0
while count < 3:
user = input('>>>')
pwd = input('>>>')
if user == 'alex' and pwd == '123':
print('欢迎登陆')
print('..........')
break
else:
print('用户名或者密码错误')
count = count + 1

今日内容：

python开发IDE： pycharm、eclipse

# 专业版
# 不要汉化

1、运算符
结果是值
算数运算
a = 10 * 10
赋值运算
a = a + 1 a+=1

结果是布尔值
比较运算
a = 1 > 5
逻辑运算
a = 1>6 or 1==1
成员运算
a = "蚊" in "郑建文"

2、基本数据类型

数字 int ，所有的功能，都放在int里
a1 = 123
a1 = 456

- int
将字符串转换为数字
a = "123"
print(type(a),a)

b = int(a)
print(type(b),b)

num = "0011"
v = int(num, base=16)
print(v)
- bit_lenght
# 当前数字的二进制，至少用n位表示
r = age.bit_length()

字符串 str
###########################################

# 1 首字母大写
# test = "aLex"
# v = test.capitalize()
# print(v)

# 2 所有变小写，casefold更牛逼，很多未知的对相应变小写
# v1 = test.casefold()
# print(v1)
# v2 = test.lower()
# print(v2)

# 3 设置宽度，并将内容居中
# 20 代指总长度
# * 空白未知填充，一个字符，可有可无
# v = test.center(20,"中")
# print(v)

# test = "alex"
# v = test.ljust(20,"*")
# print(v)

# test = "alex"
# v = test.rjust(20,"*")
# print(v)

# test = "alex"
# v = test.zfill(20)
# print(v)

# 4 去字符串中寻找，寻找子序列的出现次数
# test = "aLexalexr"
# v = test.count('ex')
# print(v)

# test = "aLexalexr"
# v = test.count('ex',5,6)
# print(v)

# 欠
# encode
# decode

# 5
# 以什么什么结尾
# 以什么什么开始
# test = "alex"
# v = test.endswith('ex')
# v = test.startswith('ex')
# print(v)

# 6 expandtabs,断句20，
# test = "username email password laiying ying@q.com 123 laiying ying@q.com 123 laiying ying@q.com 123"
# v = test.expandtabs(20)
# print(v)

# 7 从开始往后找，找到第一个之后，获取其未知
# > 或 >=
# test = "alexalex"
# 未找到 -1
# v = test.find('ex')
# print(v)

# 8 index找不到，报错忽略
# test = "alexalex"
# v = test.index('8')
# print(v)

# 9 格式化，将一个字符串中的占位符替换为指定的值
# test = 'i am {name}, age {a}'
# print(test)
# v = test.format(name='alex',a=19)
# print(v)

# test = 'i am {0}, age {1}'
# print(test)
# v = test.format('alex',19)
# print(v)

# 10 格式化，传入的值 {"name": 'alex', "a": 19}
# test = 'i am {name}, age {a}'
# v1 = test.format(name='df',a=10)
# v2 = test.format_map({"name": 'alex', "a": 19})

# 11 字符串中是否只包含字母和数字
# test = "123"
# v = test.isalnum()
# print(v)
# str

# 12 是否是字母，汉子
# test = "as2df"
# v = test.isalpha()
# print(v)

# 13 当前输入是否是数字
# test = "二" # 1，②
# v1 = test.isdecimal()
# v2 = test.isdigit()
# v3 = test.isnumeric()
# print(v1,v2,v3)

# 14 是否存在不可显示的字符
# 制表符
# 换行
# test = "oiuas dfkj"
# v = test.isprintable()
# print(v)

# 15 判断是否全部是空格
# test = ""
# v = test.isspace()
# print(v)

# 16 判断是否是标题
# test = "Return True if all cased characters in S are uppercase and there is"
# v1 = test.istitle()
# print(v1)
# v2 = test.title()
# print(v2)
# v3 = v2.istitle()
# print(v3)

# 17 ***** 将字符串中的每一个元素按照指定分隔符进行拼接
# test = "你是风儿我是沙"
# print(test)
# # t = ' '
# v = "_".join(test)
# print(v)

# 18 判断是否全部是大小写和转换为大小写
# test = "Alex"
# v1 = test.islower()
# v2 = test.lower()
# print(v1, v2)

# v1 = test.isupper()
# v2 = test.upper()
# print(v1,v2)
# 19
# 移除指定字符串
# 有限最多匹配
# test = "xa"
# # v = test.lstrip('xa')
# v = test.rstrip('9lexxexa')
# # v = test.strip('xa')
# print(v)

# test.lstrip()
# test.rstrip()
# test.strip()
# 去除左右空白
# v = test.lstrip()
# v = test.rstrip()
# v = test.strip()
# print(v)
# print(test)
# 去除
# v = test.lstrip()
# v = test.rstrip()
# v = test.strip()
# print(v)

# 20 对应关系替换
# test = "aeiou"
# test1 = "12345"

# v = "asidufkasd;fiuadkf;adfkjalsdjf"
# m = str.maketrans("aeiou", "12345")
# new_v = v.translate(m)
# print(new_v)

# 21 分割为三部分
# test = "testasdsddfg"
# v = test.partition('s')
# print(v)
# v = test.rpartition('s')
# print(v)

# 22 分割为指定个数
# v = test.split('s',2)
# print(v)
# test.rsplit()

# 23 分割，只能根据，true，false：是否保留换行
# test = "asdfadfasdf asdfasdf adfasdf"
# v = test.splitlines(False)
# print(v)

# 24 以xxx开头，以xx结尾
# test = "backend 1.1.1.1"
# v = test.startswith('a')
# print(v)
# test.endswith('a)

# 25 大小写转换
# test = "aLex"
# v = test.swapcase()
# print(v)

# 26 字母，数字，下划线：标识符 def class
# a = "def"
# v = a.isidentifier()
# print(v)

# 27 将指定字符串替换为指定字符串
# test = "alexalexalex"
# v = test.replace("ex",'bbb')
# print(v)
# v = test.replace("ex",'bbb',2)
# print(v)
###################### 7个基本魔法 ######################
# join # '_'.join("asdfasdf")
# split
# find
# strip
# upper
# lower
# replace
###################### 4个灰魔法 ######################
# test = "aaaaaaasfaaaraf s"

# 一、for循环
# for 变量名 in 字符串:
# 变量名
# break
# continue

# index = 0
# while index < len(test):
# v = test[index]
# print(v)
#
# index += 1
# print('=======')

# for zjw in test:
# print(zjw)

# test = "fafafafagaa"
# for item in test:
# print(item)
# break

# for item in test:
# continue
# print(item)

# 二、索引，下标，获取字符串中的某一个字符
# v = test[3]
# print(v)

# 三、切片
# v = test[0:-1] # 0=< <1
# print(v)

# 四、获取长度
# Python3： len获取当前字符串中由几个字符组成
# v = len(test)
# print(v)

# 注意：
# len("asdf")
# for循环
# 索引
# 切片

# 五、获取连续或不连续的数字，
# Python2中直接创建在内容中
# python3中只有for循环时，才一个一个创建
# r1 = range(10)
# r2 = range(1,10)
# r3 = range(1,10,2)
# 帮助创建连续的数字,通过设置步长来指定不连续
# v = range(0, 100, 5)
#
# for item in v:
# print(item)

##### 练习题：根据用户输入的值，输出每一个字符以及当前字符所在的索引位置 #####
# test = input(">>>")
# for item in test:
# print(item)

# 将文字对应的索引打印出来：
# test = input(">>>")
# print(test) # test = qwe test[0] test[1]
# l = len(test) # l = 3
# print(l)
#
# r = range(0,l) # 0,3
# for item in r:
# print(item, test[item]) # 0 q,1 w,2 e

# test = input(">>>")
# for item in range(0, len(test)):
# print(item, test[item])

###################### 1个深灰魔法 ######################
# 字符串一旦创建，不可修改
# 一旦修改或者拼接，都会造成重新生成字符串

# name = "zhengjianwen"
# age = "18"
#
# info = name + age
# print(info)

1.expandtabs断句实现效果：

test="username	email	password
nidegui	qq.com	123
nidegui	qq.com	123
nidegui	qq.com	123
"
v=test.expandtabs(6)
print(v)

　　截图：

2. isalpha 判断是否是字符串

test="nidegui2"
v=test.isalpha()
print(v)

　　截图：

3.判断是否数字

isdecimal

isdigit，但是特殊的字符，如@ ；isdigit可以解析，

test="123"
v1=test.isdecimal()
v2=test.isdigit()
print(v1,v2)

　　结果：