python已知有列表_python列表(list)

#str #类,字符串#name = "raitorei" #创建一个对象

#list #类,列表##############list类中提供的方法(灰魔法)###################对象.方法(..) ,li对象调用append方法#li = [1,2,3,4]#1在原来值最后追加#li.append(5)#li.append([11,22])#li.append("raito")#print(li)

#2.清空列表#li.clear()#print(li)

#3.拷贝,浅拷贝#v = li.copy()#print(v)

#4.计算元素出现的次数#v = li.count(2)#print(v)

#5.扩展愿列表#li = [1,2,3,4,5]#li.append([4645,"fdafafd"])#[1, 2, 3, 4, 5, [4645, 'fdafafd']]#li.extend([4645,"fdafafd"])#[1, 2, 3, 4, 5, 4645, 'fdafafd']#li.extend("风动旛动") #[1, 2, 3, 4, 5, '风', '动', '旛', '动']#print(li)

#6.根据值获取改值索引位置,左边有限#li = [1,2,3,4,5,2]#v = li.index(2)#print(v)

#7.在指定位置插入元素#li = [1,2,3,4,5]#li.insert(0,99)#print(li)

#8.删除某个值并获取当前的值(默认最后一个,可以指定索引)#li = [1,2,3,4,5]#v = li.pop()#v = li.pop(1)#print(li)#print(v)

#9.删除列表中指定的值，左边优先#li = [1,2,3,4,5]#li.remove(2)#print(li)#ps: pop,remove,del,li[0],del li[7:9],clear

#10.讲列表翻转#li = [1,2,3,4,5]#li.reverse()#print(li)

#11.排序#li = [1,2,3,4,5]## li.sort()#li.sort(reverse=True)#print(li)

###############深灰魔法#####################1.列表格式：中括号括起来,英文逗号分割每个元素,#列表中的元素可以使数字，字符串，列表，布尔值#集合内部可以防止任何东西#li = [1,2,"tsukirei",["轰",["Carole","Tuesday"],"绿谷"],"凌江"]#2.索引取值#print(li[2])#3.切片取值,切片结果也是列表#print(li[2:5])#4.for循环取值#for i in li:#print(i)#li = [1,2,"tsukirei",["轰",["Carole","Tuesday"],"绿谷"],"凌江"]#5.索引修改#li[1] = 120#print(li)#li[1] = [1,2,3,4]#print(li)#6.切片修改#li[0:1] = [10,20]#print(li)#7.删除#del li[1]#print(li)#8.是否存在某值#li = [1,2,"tsukirei",["轰",["Carole","Tuesday"],"绿谷"],"凌江"]#v = 1 in li#print(v)#9.索引嵌套取值#li = [1,2,9,"tsukirei",["轰",["Carole",[12,13],"Tuesday"],"绿谷"],"凌江"]#print(li[4][1][1][0])#10.转换(字符串可以转列表,数字不能直接转列表)#s = "qavapkhvakfjdkdf"#li = list(s)#print(li)#s = 123#li = list(str(s))#print(li)#11.列表转字符串#li = [1,2,3,"123","raito"]#r = str(li)#print(r) #[1, 2, 3, '123', 'raito']#如果有数字和字符串只能自己循环#s = ""#for i in li:#s += str(i)#print(s)#如果只有字符串,可以用下面的方法#li = ["123","raito"]#v = "".join(li)#print(v)

#补充：字符串创建不可以修改#li = [1,2,3,4]#print(li[0])#li[0] = 546#print(li)s= "raitorei"

print(s[0])

s[0]= "e" #报错

print(s)