Considerations for using division in Python _python

This article illustrates the considerations of division in Python, which is a very important skill, and has good reference value for Python programming. The specific analysis is as follows:

Now look at the following example:

def avg (*rest): Return (A/A (rest)) 
  /(1 + len (rest)) 
# Sample Use 
avg (1, 2)    # 1.5 
avg (1 , 2, 3, 4) # 2.5 

The source program is just to demonstrate the use of variable-length parameters, but in the Python 2.7.1 interpreter, I get a different result than the annotation.

>>> def avg (*rest): 
...   return (i + sum (rest))/(1 + len (rest)) 
...  
>>> avg (1, 2) 
1 
>>> avg (1, 2, 3, 4) 
2 

It is obvious that the data after the decimal point has been truncated, I remember two integer division, "//" should be the rounding, I remember wrong?

>>> def avg (*rest): 
...   Return (A. (rest))//(1 + len (rest)) # change '/' to '//' 
...  
>>> avg (1, 2) 
1 
>>> avg (1, 2, 3, 4) 
2 

"/" changed to "//", the result is the same, "//" is indeed to take this point I am not mistaken, but why "/" The result is truncated?

The same program I tested in 3.4.1 's interpreter and got the desired result:

>>> def avg (*rest): 
...   return (i + sum (rest))/(1 + len (rest)) 
...  
>>> avg (1, 2) 
1.5 
>>> avg (1, 2, 3, 4) 
2.5 
>>> def avg (i, *rest): 
... Return (A. (rest))   //(1 + len (rest)) # change '/' to '//' 
...  
>>> avg (1, 2) 
1 
>>> avg (1, 2, 3, 4) 
2 

You can see in 3.4.1 's interpreter that the result of "/" keeps the decimal bit, and "//" is the result of rounding

After the search, I found the question on StackOverflow: How do you force division in Python as a floating-point number? Note that this is for the 2.x version, there is no such problem in 3.x
The first two solutions to the answer are very good:

Method 1:

>>> from __future__ Import Division 
>>> A = 4 
>>> b = 6 
>>> c = a/b
   >>> C 
0.66666666666666663 

Method 2:

Similar to the practice in C language:

c = a/float (b)

I believe the example described in this article will help you with your Python programming.