廖雪锋笔记3:类型转换

数字字符串转整型，浮点型,字符串要求全为数字

(int)("222")

(float)("2222")

布尔型:转为整形

  int(True)-->1

  int(False)--->0

整形,浮点型转字符串

str(1),str(11.2)

>>> a=range(5)
>>> list(a)
[0, 1, 2, 3, 4]
>>> a
range(0, 5)

>>> list(range(5))
[0, 1, 2, 3, 4]

>>> type(a)
<class 'range'>

>>> type([2])
<class 'list'>

L = ('Bart', 'Lisa', 'Adam')
for x in L:
    print(x)

L = ['Bart', 'Lisa', 'Adam']
for x in L:
    print(x)

字典:hash

  k= {key1：value1,key2:value2,key3:value3 }

  c=k[key1]

 key in dic

dic.get(key)

dic.pop(key)

集合:

k={a,b,c}

k=set([a,b,c])

>>> a={2,3,5}
>>> type(a)
<class 'set'>

add() remove()  |  &

>>> bool(1)
True
>>> bool('')
False