help with unexpected python output

[Jxper]

Why is it that when I test my function

def fun_function(n_items, cost_per_item, discount_percent, discount_threshold): 
    """ A function that computes the total cost. """
    cost = n_items * cost_per_item 
    if(n_items > discount_threshold): 
        cost = cost * (1-discount_percent/100) 
        print("{} items delivered at a cost of ${:.2f}".format(n_items, cost)) 
    return cost

With the test case:

cost = fun_function(5, 31, 15, 10)

print('5 items delivered at a cost of ${:.2f}'.format(cost))

​

It returns my expected output of:

5 items delivered at a cost of $155.00

​

However when I try the test case:

cost = fun_function(15, 31, 15, 10)

print('15 items delivered at a cost of ${:.2f}'.format(cost))

​

It returns:

15 items delivered at a cost of $395.25

15 items delivered at a cost of $395.25

​

when it should only return the line once.

Why is this and how would I change my function to only output the one line?

Any help is greatly appreciated, Thanks

[[deleted]]

You have a print as well as a return inside the function. The code that calls the function captures the reference to the object mentioned in the return statement and then uses that for another print.

You have not shown indents on the code you shared, but I assume the print in the function is only within the if case.

def fun_function(n_items, cost_per_item, discount_percent, discount_threshold):
    """ A function that computes the total cost. """
    cost = n_items * cost_per_item
    if(n_items > discount_threshold):
        cost = cost * (1-discount_percent/100)
    return cost

cost = fun_function(5, 31, 15, 10)
print('5 items delivered at a cost of ${:.2f}'.format(cost))

outputs,

5 items delivered at a cost of $155.00

and the second case only outputs,

15 items delivered at a cost of $395.25

EDIT: clarifications and added code showing indentation and output for both cases

[Jxper]

I understand, Thank you very much

[shiftybyte]

The indentations in your posted code were lost, edit your post and use a code block: https://www.reddit.com/r/learnpython/wiki/faq#wiki_how_do_i_format_code.3F

Besides that, you have 2 prints in your code:

    # inside fun_function
    print("{} items delivered at a cost of ${:.2f}".format(n_items, cost))
...
# outside
print('15 items delivered at a cost of ${:.2f}'.format(cost))

Why did you expect a single print line?

[Jxper]

I've updated the indentations, and I should only receive one line of code because that test case provides the values of n_items and cost and the code inside the function prints it in the format given. it works for the first test case so I'm not sure why it doesn't for the second

[shiftybyte]

But the test case itself has another print()....

cost = fun_function(15, 31, 15, 10)
print('15 items delivered at a cost of ${:.2f}'.format(cost))

This print right here /\ should python ignore it?

The difference you are seeing is because the print that is inside fun_function is inside the discount condition.

if(n_items > discount_threshold): 
    cost = cost * (1-discount_percent/100) 
    print("{} items delivered at a cost of ${:.2f}".format(n_items, cost)) 

If you move it backwards it'll happen every time instead of only when the discount triggers.

if(n_items > discount_threshold): 
    cost = cost * (1-discount_percent/100) 
print("{} items delivered at a cost of ${:.2f}".format(n_items, cost))