Having difficulty understanding how function works

Question

I've written a function in python to see If i know what I'm doing but unfortunately I'm not. I thought my defined arg variable will hold a number and multiply each of the numbers which *args variable holds and print it all at a time. But, it is giving me the first result only.

This is what I've written:

def res_info(arg,*args):
   for var in args:
    return var*arg

print(res_info(2,70,60,50))

Having:

Expected:

140
120
100

I don't understand why I'm not getting all the results. Thanks for taking a look into it.

return will always end(?) the function; the function call stops at 70*2 — Wiggy A., Oct 22 '17 at 07:29
`return` will end the function at the first iteration, so you'll end up with 140 as result. — Chiheb Nexus, Oct 22 '17 at 07:30

Kaushik NP · Accepted Answer · 2017-10-22T07:41:59.073

3

You are on the right path. The problem you had was due to your use of the return statement. Use yield instead.

>>> def res_info(arg,*args): 
        for var in args: 
            yield var*arg 

>>> list(res_info(2,70,60,50))
=> [140, 120, 100]

So, what was happening was, even though your logic was correct, since there was a return statement in the loop, your loop hence was never fully executed and your program scope would come out on the first iteration of the loop itself (ie, when var = 70).

Using yield, solved the problem as it returns a Generator object after all calculations, and hence does not exit the loop like return does.

edited Oct 22 '17 at 07:41

answered Oct 22 '17 at 07:26

Kaushik NP

6,733
9
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Thanks for the clarity along with `yield` function. – SIM Oct 22 '17 at 08:10
@shayan : sure. Glad to help. – Kaushik NP Oct 22 '17 at 08:11

score 2 · Answer 2 · answered Oct 22 '17 at 07:51

2

def res_info(arg,*args):
    result = []
    for var in args:
        result.append(var*arg)
    return result

print(res_info(2,70,60,50))

answered Oct 22 '17 at 07:51

Avijit Dasgupta

2,055
3
22
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Thanks Avijit Dasgupta, for your answer. It produces what I expected. +1 for this. – SIM Oct 22 '17 at 08:13
@shayan This isn't list comprehension – Abid Hasan Oct 22 '17 at 08:14

Having difficulty understanding how function works

2 Answers2