python基础_数据类型

1、 整形  int

　　python3里面，数字用int

# int 将字符串转换成数字
a = "123"
b = int(a) +1
print(b)

# type()查看字符类型
print(type(a),a)
print(type(b),b)

# base 进制转换
num = "a"
v = int(num,base=16)
print(v)

# 当前数字的二进制至少用n位来表示
age = 3
r =age.bit_length()
print(r)

age = 2
r =age.bit_length()
print(r)

>>>124

>>><class 'str'> 123
>>><class 'int'> 124

>>>10

>>>2

>>>2

2、字符串 str

# capitalize()首字母大写,其他字母小写
test = "aLex"
v = test.capitalize()
print(v)

# 所有的字符变小写，casefold()功能更强大
v1 = test.casefold()
print(v1)
v2 = test.lower()
print(v2)

>>>Alex

>>>alex
>>>alex

# center（20 ，"*"） 20代指长度，* 空白未知填充
test = "aLex"
v = test.center(20,"*")
print(v)

# count("ab",4,6)计算字符存在的次数,4 代表起始位置，6 代表结束位置
test = "aaabbbcdlab"
v = test.count("ab",4,6)
print(v)

>>>********aLex********

>>>0

# endswith()以什么结尾  startswith()以什么开始
test = "alex"
v = test.endswith("a")
v1 = test.startswith("ex")
print(v,v1)

# 从前往后找，找到第一个后，获取其位置
# find('ex',6,9) 6是从第6个字符开始找，到第9个结束,从0开始数 开区间包小不包大
test = 'alexallexll'
v = test.find('ex')
v1 = test.find('ex',6,9)
print(v)
print(v1)

>>>False False

>>>2

>>>7

 

# 格式化，将一个字符串中的占位符替换指定的值
test = 'i am {name}, age {a}'
print(test)
v = test.format(name = "alex",a =10)
print(v)
test1 = 'i am {0}, age {1}'
v1 = test1.format("alex",10)
print(v1)

# 格式化 传入的值以字典形式
v3 = test.format_map({"name":"alex","a":19})
print(v3)

>>>i am {name}, age {a}
>>>i am alex, age 10
>>>i am alex, age 10

>>>i am alex, age 10

3、布尔值 bool

 

4、列表 list

 

5、元组 tuple

 

6、字典 dict