一.基本数据类型
(1)numbers 数字
- 整型 int
a = 1
print (type(a))
- 长整型 long
- python3.x 中无此类型
>>> 2 ** 100 1267650600228229401496703205376L
- 布尔型 boor
- True
- False
print (1 > 2) print (1 < 2)
- 浮点型 float
a = 1.0
print (type(a))
- 复数 complex
- 6.23+1.5j -1.23-987j
(2)字符串 str
name1 = 'zhengying' print (type(name1))
(3)元组(tuple)
- 定义:
- 变量后面接的是 ()
- 括号内为空时,则是一个空元组
- 括号内只有一个元素时,则不为元组,由括号内元素类型定义
- 要想实现括号内只有一个元素的元组,则需要在该元素后面加入逗号","
- 特点:
- 不能对元组进行修改/删除/插入元素操作
stu = () stu1 = (1) stu2 = ("hello") stu3 = (1.01) stu4 = ("zhangsan","lisi","wangwu")
(4)列表(list)
- 定义:
- 变量后面接的是 []
- 无论 [] 内为空或者只有单个/多个值时,都为列表
- 特点:
- 支持对列表进行修改/删除/插入元素操作
stu = [] stu1 = [1] stu2 = ["zhangsan","lisi","wangwu"] print (stu,stu1,stu2)
(5)字典(dict)
- 字典是python中唯一的映射类型,采用键值对(key-value)的形式存储数据
- 定义:
- 变量后面接的是 {}
- {} 内为空值时,则为空字典
- 字典括号内为键值对格式 如 {"key1":"value1","key2":"value2"}
- 特点: 键唯一,可哈希,不可修改(不可变类型)
- 无序
- 不可变类型有:整型,字符串,元组
- 可变类型有:列表,字典
dic = {"name1":"zhangsan","age":{"age1":"18","age2":20}, "name2":"lisi","name3":"wangwu"}
stu = {"name":"zhangsan","age":28,"sex":"boy"} print (stu) print (type(stu))
(6)可变集合(set)
- 定义:
- 变量后面接的是 {},但是括号内不是键值对格式
- 自动去重
- 无序的
a = {1,2,3} print (a) print (type(a))
二.数据类型的转换
1.int 转 str
a = 123 print (str(a)) print (type(str(a)))
2.str 转 int
a = "123" print (int(a)) print (type(int(a)))
3.str 转 list
a = "123" print (list(a)) print (type(list(a)))
4.str 转 tuple
a = "123" print (tuple(a)) print (type(tuple(a)))
5.list 转 tuple
a = [1,2,3] print (tuple(a)) print (type(tuple(a)))
6.tuple 转 list
a = (1,2,3) print (list(a)) print (type(list(a)))
7.list 转 set
a = [1,2,3] print (set(a)) print (type(set(a)))
8.tuple 转 set
a = (1,2,3) print (set(a)) print (type(set(a)))
9.set 转 list
a = {1,2,3} print (list(a)) print (type(list(a)))
10.set 转 tuple
a = {1,2,3} print (tuple(a)) print (type(tuple(a)))