python第一天第二天
#1.python中的输出语句 ==>用print()函数进行输出# print('hello world')
# str1 = 'hello world'
# print(str1)
# 2.python的格式化输出
# %s
# name = 'xian03'
# print('xian03 is number one')
# print('%s is number one'%name)
#%c
# name = 'x'
# num = '1'
# print('name is number one')
# print('%c is number one'%name)
# print('%c is number one'%num)
#%d
#%i
# num = 12
# print('number is %d'%num)
# print('number is %i'%num)
#%o
# num = 12
# print('number is %o'%num)
#%x
# num = 12
# print('number is %x'%num)
# #%f
# num = 12
# print('number is %f'%num)
# #%%
# num = 12
# print('number is %d%%'%num)
#python中的注释
# print('xian03 is "number" one')
# print("xian03 is 'number' one")
# print("xian03 is '''number''' one")
#正确的变量的写法
# name = 'xiaozhang'
# name1 = 'xiaozhang'
# name_1 = 'xiaozhang'
# user_name = 'admin'
# user_name_1 = 'admin1'
# print(name)
#1name = 'xiaozhang'命名变量，数字不能开头
# __ = 'xiaozhang'不能使用
# _name = 'xiaozhang'有特殊意义，单下划线的变量不能被导入到其他模块中使用
# __name = 'xiaozhang'有特殊意义，只能给到类本身使用
# Name = 'xiaozhang'有特殊意义，一般定义类的时候，采用首字母大写
# NAME = 'xiaozhang'有特殊意义，一般字母全部大写，表示的是常量（不可变的量）
# 3 = 'xiaozhang'数字不能当成一个变量
# if = 'xiaozhang' if是python中的保留关键词，不能用来定义变量
#python中的输入语句
#input()
# phone =input('请输入你的手机号码')
# if phone == '13355556666':
# input('输入号码正确')
# else:
# input('输入号码有误')
#python常见的运算符
# 1.算数运算符
# a = 5
# b = 3
# print(a + b)
# print(a - b)
# print(a * b)
# print(a / b)
# print(a % b)
# print(a // b)
# print(a ** b)
#2.赋值运算符
# a = 5
# b = 3
# a += b
# a -= b
# a *= b
# a /= b
# a %= b
#3.比较运算符
# a = 5
# b = 3
# c = 5
# print(a > b)
# print(a < b)
# print(a == c)
# print(a != c)
# print(a <= c)
# print(a >= c)
#4.逻辑运算符
# a = 5
# b = 3
# c = 5
# print(a > b and a < c)
# print(a > b and a <= c)
# print(a > b or a < c)
# print(a < b or a != c)
# print(not a > b)
# print(not a < b)
#5.python中的成员运算符
# list1 = ['xian01','test','10086',10010]
# print('xian01' in list1)
# print(10010 in list1)
# print('10010' in list1)
# print('xian01' not in list1)
#应用
# list1 = ['xian01','test','10086',10010]
# if 'test' in list1:
# input('测试成功')
# else:
# input('测试失败')
#6.python中的位运算符
# 一.按位与运算符,符号为&
# a = 5
# b = 11
# print(a & b)
'''
存储单位
1TB = 1024GB
1GB = 1024MB
1MB = 1024KB
1KB = 1024BIYE
1BIYE = 8BIT
0 0 0 0 0 0 0 0
128 6432168 4 2 1
a = 5 把十进制中的5转换成二进制为00000101 ==> 二进制中的5
b = 11 把十进制中的11转换成二进制00001011 ==> 二进制中的11
计算
00000101
00001011
--------
00000001
'''
# 按位或运算符
# a = 5
# b = 11
# print(a | b)
'''
00000101
00001011
--------
00001111 ==>8 + 4 + 2 + 1
'''
# a = 5
# b = 11
# print(a | b)
#按位异或运算符
# a = 5
# b = 11
# print(a ^ b)
'''
00000101
00001011
--------
00001110
'''
#按位取反运算符
# a = 5
# b = 11
# print(~a)
#左移动运算符
# a = 5
# b = 11
# print(a << 2)
# '''
# 00000101
# 00010100
# '''
# #右移动运算符
# a = 5
# b = 11
# print(b >> 2)
# '''
# 00001011
# 00000010
# '''
#练习
a = 8
b = 24
print(b >> 2)
'''
0 0 0 0 0 0 0 0
128 6432168 4 2 1
十进制8 ==>00001000
十进制24 ==>00011000
计算a & b
00001000
00011000
--------
00001000 ==>8
计算a | b
00001000
00011000
--------
00011000 ==>24
计算a ^ b
00001000
00011000
--------
00010000 ==>16
计算a << 2
00001000
00100000 ==>32
计算b >> 2
00011000
00000110 ==>6
'''#1.python中的索引
# str1 = 'duoceshi'
# #正向索引
# print(str1)
# print(str1)
# print(str1)
# print(str1)
# #负向索引
# print(str1[-1])
# print(str1[-5])
# print(str1[-9])
# #2.python中的切片
# str1 = 'duoceshi'
# #当步长为正数的时候
# print(str1)
# print(str1)
# print(str1)
# print(str1[-6:-2])
# print(str1)
# print(str1[:5])
# print(str1)
# print(str1[:])
# #当步长为负数的时候
# print(str1)
# print(str1[-2:-6:-1])
# print(str1)
# print(str1[:-4:-1])
# print(str1[-2::-1])
# print(str1[::-1])
# #跳切
# print(str1)
# print(str1[-1:-7:-2])
# #怎么去序列所有的值，怎么对序列进行翻转
# print(str1[:])
# print(str1[::-1])
# #面试题
# #给你一个字符串，怎么取字符串最后的两个元素
# print(str1)
# print(str1[-2:])
#python中的字符串
#字符串定义str1 = '' 数据类型用str
#字符串的函数
#1.capitalize()函数，可以把字符串的首字母大写
# str1 = 'xiao zhang'
# # print(str1.capitalize())
# # 2.title()函数，可以把字符串中的首字母大写
# print(str1.title())
# # 3.count()函数，统计某个字符在字符串中出现的次数
# print(str1.count('a'))
# 4.join(),把字符串的字符按照自定义的链接符号连接在一起
# str1 = 'xiao zhang'
# print('_'.join(str1))
# 5.split()透过某个字符进行分割字符串，最终得到的结果为列表list
# str1 = 'xiao zhang'
# print(str1.split(' '))
# print(type(str1))
# print(type(str1.split(' ')))
# list1 = str1.split(' ')
# print(list1)
# 通过索引取值
# print(list1)
# print(list1)
# print(list1)
# split()应用场景
#把字符串str1 = 'user_name'输出成UserName
# str1 = "user_name"
# list1 = str1.title().split('_')
# print(list1+list1)
# print(''.join(list1))
# 6.strip()函数，删除开头和结尾的字符，以什么字符开头和结尾
# str1 = 'duoceshidu'
# print(str1.strip('du'))
# print(str1.strip('d'))
# print(str1.strip('ud'))
# print(str1.strip('u'))
# 7.lstrip()函数，删除字符串的开头
# str1 = 'duoceshidu'
# print(str1.lstrip('du'))
# print(str1.lstrip('d'))
# print(str1.lstrip('u'))
# print(str1.lstrip('ud'))
# 8.rlstrip()函数，删除字符串的结尾
# str1 = 'duoceshidu'
# print(str1.rstrip('du'))
# print(str1.rstrip('u'))
# print(str1.rstrip('d'))
# print(str1.rstrip('ud'))
页:
[1]