s1 = "123"
print(type(s1)，s1)
b = int(s1)#不加base默认转换为十进制
print(type(b),b)
b += 1000

s1 = "0011"
s2 = "a"
print(type(s1),s1)
b = int(s1,base=2)#二进制
c = int(s2,base=16)#十六进制
print(type(b),b)
print(type(c),c)

age = 7
# 7 111
# 3 11
# 1 01
# 当前数字的二进制至少用n位表示
r = age.bit_length()
print(r)# 3

#!/usr/bin/env python
# -*- coding:utf-8 -*-

test = 'helLo'
v = test.capitalize() # 首字母大写
print(v) # Hello
v1 = test.casefold() # 所有变小写，更牛逼
print(v1) # hello
v2 = test.lower() # 所有变小写
print(v2) # hello

# 设置宽度，并将内容居中
# 20 代指总长度
# * 空白未知填充，一个字符，可有可无
v3 = test.center(20,'*')
print(v3) # *******helLo********

# 去字符串中寻找子序列出现的次数
v4 = test.count('l',4)
print(v4) # 0
# 以什么什么结尾或开始,返回bool
v5 = test.endswith('lo')
v6 = test.startswith('h')
print(v5)
print(v6)

# 从开始往后找，找到第一个之后，获取其位置
test1 = 'hellohello'
v7 = test1.find('oh', 4, 6) # 大于等于4，小于6
print(v7) # 4

# 格式化，将字符串中的占位符替换为指定的值
test2 = 'i am {name}, age {a}'
print(test2) # 'i am {name}, age {a}'
v8 = test2.format(name='Alex',a=18)
print(v8) # i am Alex, age 18

test3 = 'i am {0}, age {1}'
print(test3) # 'i am {0}, age {1}'
v9 = test3.format('Alex',18)
print(v9) # i am Alex, age 18

v10 = test2.format_map({"name":'Alex',"a":18})
print(v10) # i am Alex, age 18

v11 = test3.index("am")
print(v11)

# 判断字符串是否只包含数字和字母
v12 = test2.isalnum()
print(v12) # False