python相关代码面试题

# 输出每个字母出现的次数
s1 = ' aaaabbbbcccddddaa '
s2 = ''
for i in range(len(s1)):
    if s1[i] in s2:
        continue
    count = 0
    for j in range(i,len(s1)):
        if s1[i] == s1[j]:
            count += 1
    s2 += s1[i] + str(count)
print(s2)

def additem(listP):
    listP  + = [1]
mylist = [1,2,3,4]
additem(mylist)
k = len(mylist)
print(mylist) # [1,2,3,4,1]
print(k) #5

#=========================================================#
counter = 0
def doThings():
    global counter
    for i in (1,2,3):
        counter += 1
doThings()
print(counter)# 6

print('==========+++++++++++++===========')

class Person:
    def __init__(self,id):
        self.id = id
    
jack = Person(1)
jack.__dict__['age']=22
oo = jack.age + len(jack.__dict__)
print(jack.__dict__)# {'id':1,'age':22}
print(oo)# 22+2

# 魔法函数 __doc__属性
def foo():
    "This is cool simple function that return 1"
    return 1

print(foo.__doc__[-8:-2])

#===================================================#
class A:
    def __init__(self,a,b,c):
        self.x = a+b+c

a = A(1,2,3)
b = getattr(a,'x')
print(b) # 6
setattr(a,'x',b+1)
print(a.x)# 7