1.python不用声明变量的类型，运行时python自己进行判断

2.尽量不要用“+”去拼接字符串，运行时会每遇到一个“+”就开辟一块内存空间，使用如下方式进行字符串的拼接。

msg='''
information of user %s
-----------------------
name:   %s
age :   %d
job :   %s
-----------end---------
'''%(name,name,age,job)

print(msg)

3.列表的语法和练习

python中叫列表，在其它语言中叫数组。

#命名列表
name=["mark","jack","Tang long"]
age=9
#列表中可以放任何类型 ，也可以放变量
name=["mark","jack","Tang long",22,age,56,22,47,88,9,5,6,7]
#列表取值
print("name-----",name)
print("name[1]-----",name[1])
print("name[-1]-----",name[-1])
print("name[0:6]-----",name[0:6])
print("name[:6]-----",name[:6])
print("name[:6][2:4]---",name[:6][2:4])
print("name[:6][2:4][0]---",name[:6][2:4][0])
print("name[:6][2:4][0][1]---",name[:6][2:4][0][1])
print("name[-5:-1]-----",name[-5:-1])
print("name[-5:]-----",name[-5:])

# 修改
name[1]="Wangminghu"
print("name====",name)
#插入,一次只能插一个
name.insert(2,"MingGou")
print("name====",name)
#追加
name.append("Alex")
print("name====",name)
#删除
name.remove("MingGou")
print("name====",name)

#运行结果
name----- ['mark', 'jack', 'Tang long', 22, 9, 56, 22, 47, 88, 9, 5, 6, 7]
name[1]----- jack
name[-1]----- 7
name[0:6]----- ['mark', 'jack', 'Tang long', 22, 9, 56]
name[:6]----- ['mark', 'jack', 'Tang long', 22, 9, 56]
name[:6][2:4]--- ['Tang long', 22]
name[:6][2:4][0]--- Tang long
name[:6][2:4][0][1]--- a
name[-5:-1]----- [88, 9, 5, 6]
name[-5:]----- [88, 9, 5, 6, 7]
name==== ['mark', 'Wangminghu', 'Tang long', 22, 9, 56, 22, 47, 88, 9, 5, 6, 7]
name==== ['mark', 'Wangminghu', 'MingGou', 'Tang long', 22, 9, 56, 22, 47, 88, 9, 5, 6, 7]
name==== ['mark', 'Wangminghu', 'MingGou', 'Tang long', 22, 9, 56, 22, 47, 88, 9, 5, 6, 7, 'Alex']
name==== ['mark', 'Wangminghu', 'Tang long', 22, 9, 56, 22, 47, 88, 9, 5, 6, 7, 'Alex']

 列表练习，打印结果前的数字为代码的行号：

name=["Alex","jack","Rain","Eric","Monica","Fiona"]
print('2 name====',name)
#插入
name.insert(-1,'MingHU')
print('5 name===',name)
name.insert(4,'MingLong')
print('7 name===',name)
#取值
name2=name[2:7]
print('10 name2===',name2)
#删除
name.remove('Fiona')
print('13 name===',name)
#连续删除用python的全局函数del删除内存的数据
del name[4:6]
print('16 name===',name)
#del name 删除这个变量
print('18 name===',name)
name[4]="wangminglong(leader)"
print('20 name===',name)
#每隔一个取一个,最后一个数字为步长
print('22 name===',name[0::2])#或者print('name===',name[::2])
name=["Alex","jack","Rain",9,47,5,6,8,4,"Eric","Monica",9,6,9,4,5,"Fiona"]
name3=['zhangsan','lisi','zhaoliu']
#判断name中是否有9
print(9 in name)
if(9 in name):
    num_of_ele=name.count(9)#对9进行计数
    position_of_ele = name.index(9)#查找9的位置
    name[position_of_ele]=999
    print('31 [%s] 9 are/is in nam