python int str

1. int 类型转换

a = "123"
b = int(a)
b = b+10
print(type(a),a)
print(type(b),b)

2. int(num,base=2), base不写的时候默认为10

a = "0011"
b = int(a,base=2)
print(b)

　　答案为 3.

3. -.bit_length() 当前数字为2进制时，至少要用多少位来表示

a = 8
b = a.bit_length()
print(b)

　answer：4

4. str 居住 center()

a = "kkkk"
b = a.center(20,"&")
print(b)
#"&"中只能填一个

&&&&&&&&kkkk&&&&&&&&

5. str 之count()计数

count(self, sub, start=None, end=None)

a = "kkkkrrrrrrrrrxxxxxxxxx"
b = a.count('r',5,14)
print(b)

8

6. find(self, sub, start=0, end=_sys.maxsize) 比index()好用

a = "djalskfjs;kd k"
b = a.find("ja",0,20)
print(b)

1

7. format(self, *args, **kwargs ) 两种方式效果一样

a = 'jkldak{ff},ioeu{gg}'
b = a.format(ff='JOAN',gg='HUMAN')
print(b)

a = 'jkldak{0},ioeu{1}'
b = a.format('JOAN','HUMAN')
print(b)

jkldakJOAN,ioeuHUMAN

8. format_map(self, mapping)

format_map(self, mapping): # real signature unknown; restored from __doc__

9. def isalnum(self, *args, **kwargs): # real signature unknown

  Return True if the string is an alpha-numeric string, False otherwise.