python 常见的操作
#python 常见的运算操作#1.算数运算符
#a = 9
#b = 8
#print(a + b)
#print(a - b)
#print(a * b)
#print(a / b)
#print(a % b)#取余/取模
#print(a ** b)#取幂
#print(a // b)#向下取整，取得是商值
#2.赋值运算符
# a = 4
# b = 5
# a += b
# a -= b
# a *= b
# a /= b
# a %= b
# a //= b
# a *= b
# print(a)
#3.比较运算符
#a = 3
#b = 4
#c = 4
#print(a > c)
#print(a < b)
#print(b >= c)
#print(a != c)
#print(b == c)
#4.逻辑运算符 and or not
# a = 3
# b = 4
# c = 4
# print(a < b and b == c)
# print(a >b or a == c)
# print(not b == c)
# print(not b != c)
#5.成员运算符
#int类型
# list1=("lyf","iphone","110",120)#列表，是一个存储数据的容器
# # print("lyf" not in list1)
# # print(120 not in list1)
# # print("120" not in list1)
# if 100 in list1:
# print("ok")
# else:
# print("sad")
#python中的位运算符
# a = 8
# b = 24
'''
0 0 00 0 0 0 0 ==>二进制
128 64 32 16 8 4 2 1 ==>十进制中的数值
a = 8 ==>转换成二进制
00001000 ==>二进制中的8
b =24 ==>转换成二进制
00011000 ==>二进制中的24
计算：
00001000
00011000
---------
00001000 ==>得到的结果是十进制中的8
a & b =8
'''
#按位与运算符
#print(a & b )#8
#按位或运算符
#print(a | b)#24
'''
00001000
00011000
---------
00011000 ==>得到的结果是十进制中的24
'''
#按位异或运算符
#print(a ^ b)#16
'''
00001000
00011000
---------
00010000 ==>对应的是十进制中的16
'''
#按位取反运算符
#print(~ a)#-(x+1)=-9
'''
a=8
00001000
-（8+1）= -9
'''
#按位取反运算符
#print(~ b)#-25
'''
b=24
00011000
-(x+1)=-25
'''
#左移动运算符
#print(a << 2)#32
'''
a=8
00001000 ==> 00100000 =32
'''
#右移动运算符
#print(b >>2)#6
'''
b=24
00011000 ==> 00000110 =6
'''
# python--索引
# 索引分为：使用格式str1
# 1.正向索引：从0开始，从左到右取值
# 2.负向索引：从-1开始，从右到左取值
# strl = "123456789"
# #print(strl)#6
# print(strl)#9
# print(strl[-4])#6
#python中的切片
str1 = "1234567"
# print(str1)#123456
# print(str1[:5])#12345
# print(str1)#34567
# print(str1)#空
# print(str1)#5432
# print(str1[:5:-1])#7
# print(str1)#654321
# print(str1[-6:-2])#2345
#python--字符串函数
#capitalize():字符串首字符大写
# str1 = "ni hao"
# print(str1.capitalize())#Ni hao
#title()函数返回标题化的字符串，单词的首字母大写
# str1 = "ni hao"
# print(str1.title())
#count()
# str1 = "ni hao"
# print(str1.count("n"))
# #join()
# str1 = "ni hao"
# print("_".join(str1))
# str1 = "user_name"
# list1 = ["user","_","name"]
# #print(str1.title())
# print(" ".join(list1))
# split()
# str1 = "user_name"
# print(str1.split(" "))
# list1 = str1.split(" ")
# print(list1)
# print(str1.split("0"))
# str1 = "user_name"
# # print(str1.title())
# str2 = str1.title()
# #print(type(str1.title()))
# print(str2.split("_"))
# print("".join(str2.split("_")))
#strip()函数---删除字符串开头与结尾的字符
# str1 = "nihaoya"
# print(str1.strip("ni"))#haoya
# print(str1.strip("a"))#nihaoy
#lstrip(ab)函数---删除字符串开头有ab序列字符
#str1 = "nihaoya"
#print(str1.lstrip("ni"))#haoya
# print(str1.lstrip("i"))#nihaoya
# print(str1.lstrip("ya"))#nihaoya
# print(str1.lstrip("n"))#ihaoya
#rstrip(ab)函数----
# print(str1.rstrip("ya"))#nihao
# print(str1.rstrip("y"))#nihaoya
# print(str1.rstrip("a"))#nihaoy
#startswith():判断字符串是否以什么开始
#endswith()
# print(str1.startswith("ni"))#true
# print(str1.startswith("in"))#False
# print(str1.endswith("ya"))#true
# file_name = input("请输入上传文件名称:")
# if file_name.endswith(".txt"):
# print("文件有效")
# else:
# print("文件无效")
#find()/rfind():
#str1 = "nihaoya"
# print(str1.find("h"))#2
# print(str1.find("y"))#5
#print(str1.rfind("a"))#6
# str1 = "duoceshioud"
# print(str1.find("o",3,))
#replace():replace(substring,newstring,max)
# str1 = "xiaowang"
# print(str1.replace("x","l"))#liaowang
# print(str1.replace("o","a",1))#xiaawang
# lower():转换字符串中所有大写字符为小写
# upper():转换字符串中所有小写字符为大写字母输出
# str1 = "xiaowang"
# print(str1.lower())#xiaowang
# print(str1.upper())#XIAOWANG
#isdigit():判断字符串中是否全为数字
# str1 = "ni12345"
# print(str1.isdigit())#False
# str1 = "2312345"
# print(str1.isdigit())#True
#isalnum():判断字符串当中是否全都为数字，全为字母，或者数字字母组合
# str1 = "12345"
# print(str1.isalnum())#True
# str1 = "1ac45"
# print(str1.isalnum())#True
# str1 = "1a_c45"
# print(str1.isalnum())#False
#istitle();判断字符串中首字母是否为大写，其他是否为小写，不为小写则为否
# str1 = "Xiaowang"
# print(str1.istitle())#True
#isupper()/islower:is开头的就是判断一个字符串是否展示为都是大写或者都是小写
#str1 = "xiaowang"
# print(str1.isupper())#False
# print(str1.islower())#True
#python中的列表
#定义列表
#1.方式一
# list1 = ["lyf","yyqx",101,]
# print(list1)
#2.方式二（使用int函数把字符串转换成列表）
#int(),str(),list()(都是函数）
# str1 = "lyf"
# list1 =list(str1)
# # print(list1)#['l', 'y', 'f']
# print(type(list1))#<class 'list'>
#列表中常用的函数与方法
#1.索引赋值
# list1 = ["lyf","yyqx",101,]
# list1 = "yida"
# print(list1)#['lyf', 'yyqx', 'yida', ]
# 2.切片赋值
# list1 ="nihao"
# print(list1)#['n', 'i', 'h', 'a', 'o', ]
#3.append()函数
# list1 = ["lyf","yyqx",101,]
# list1.append("jaychou")(添加字符串）
# print(list1)#['lyf', 'yyqx', 101, , 'jaychou']
# list1.append(110)#(添加整型）
# print(list1)#['lyf', 'yyqx', 101, , 110]
#4.insert()函数
# list1 = ["lyf","yyqx",]
# list1.insert(0,"yyy")
# print(list1)#['yyy', 'lyf', 'yyqx', ]
# list1.insert(2,123)
# print(list1)#['lyf', 'yyqx', 123, ]
# list1.insert(0,["aa","bb"])
# print(list1)#[['aa', 'bb'], 'lyf', 'yyqx', ]
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