Python函数返回错误

Question

I am writing a python function which uses two arrays of equal size [n,1]. Before performing any calculations, I'd like to check to ensure the lengths are the same, and if not, return an error. What is the best practice?

def do_some_stuff(array1, array2): 
# Before doing stuff, check to ensure both arrays have the same length

if len(array1) != len(array2):
#  Break and return with error

I'm confused, because I want to break and return an error code (say -1). Seems that break will return without any value, and return will continue to execute the function? Or does Return break out of any remaining code?

Answer 1

What is the best practice?

In python code, error conditions are usually indicated with exceptions. You could use raise ValueError("Arrays must have the same size") .

Using exception rather than return values to indicate errors has the added advantage that the exception would bubble up until it reaches a except statement. So you can defer the error handling up to a place where it makes sense. Also exceptions have an associated descriptive message instead of a magic number.

The break statement , as in many other languages, is used to interrupt the flow in loops, like ones created with while or for .

Answer 2

You don't need the break

def do_some_stuff(array1, array2): 
    # Before doing stuff, check to ensure both arrays have the same length

   if len(array1) != len(array2):
       return -1

Just return the error code. In this way the rest of the code of the function will not be executed.