Share several questions about python and several questions about python.

Share several questions about python and several questions about python.

This article mainly introduces several python interview questions recently encountered during the interview. I will share these questions for your reference. I will not talk about them here. Let's take a look at the detailed introduction:

I. Generate the Fibonacci series and take the first 10 items

def func(m): n,a,b = 0,1,1 while n < m: yield a a,b = b,a+b n += 1for one in func(10): print one

This can be said to be a common SIMPLE algorithm question. The key point is to understand the functions of a, B = B, a + B, and yield.

2. Expand a list. The elements in the list may also contain the list.

def myextend(alist): tmp = [] for one in alist:  if isinstance(one,list):   tmp.extend(myextend(one))  else:   tmp.append(one) return tmpt = [1,2,5,[3,[],5,2,[57]],90]print tprint myextend(t)

Evaluate the knowledge of recursive calling.

3. Write the following code.

def test(x,l=[]): for o in range(x):  l.append(o) print ltest(3)test(1,[3,2,1])test(3)

Enter the following information:

[0,1,2][3,2,1,0][0,1,2,0,1,2]

Variable types are used as parameters when passing parameters are not displayed. Each function call is shared. If parameters (such as the second type) are passed, they do not affect each other.

4. It is known that a list contains duplicate data, which maintains the sequence of the first appearance of elements in the list and removes duplicates. The complexity is O (n ).

def fun(alist): result = [] temp = set() for o in alist:  if o not in temp:   result.append(o)   temp.add(o) return result

Evaluate the complexity of common operations such as list and set.

5. If the following functions are known, write out the output and write the correct statement:

z = [lambda x:x*i for i in range(3)]x = [o(2) for o in z]print x

Output: [, 4]

Here we mainly examine the knowledge points in python when the closure and return values are functions. Since lambda functions share the I variable, When I is called, I is changed to 2, so the output is 4.

Correction:

def func(): def m(x):  def n(y):   return x * y  return n return [f(one) for one in range(3)]z = func()x = [o(2) for o in z]print x

Output [0, 2, 4]

6. Create a class and output an attribute. If this attribute exists, the output value; otherwise, the string of this attribute name is output.

class Mycls(object): a = 0 def __getattr__(self,name):  print namez = Mycls()print z.a,z.b

The output is 0 and B.

This section mainly describes the reflection mechanism of python and the _ getattr _ method related to classes.

Note:The difference between the _ getattr _ method and the _ getattribute _ method is that the former is called only when the property does not exist, and a value is returned or an exception is thrown. The latter is called every time.

For more information, seegetattr(),hasattr()This built-in function.

Short answer

• Differences between py2 and py3
• Python garbage collection mechanism
• Multi-threaded methods in python, limitations, and other methods for concurrent processing
• Epoll, select, and poll Models

Summary

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