print function doesn't execute outside a while cycle

Question

i have this function that works as intended except for the fact that the last print instruction outside the while cycle (print("why don't you print?")) never get executed and i don't understand why. after the break, the code execution should move forward.

def eval_cycle():
    done = 'done'
    last_expression = ' '
    while True:
        dato = eval(input('Insert an expression: '))
        if dato == done:
            print("Last expression is: ", last_expression)
            return dato
            break
        last_expression = dato
        print(dato)
    print("why don't you print?")

return returns immediately, before break can execute.

chepner
– chepner

2023-01-09 18:30:33 +00:00
Commented Jan 9, 2023 at 18:30 — chepner
– chepner, Commented Jan 9, 2023 at 18:30
oh right, i'm so stupid :(

jane12
– jane12

2023-01-09 18:40:50 +00:00
Commented Jan 9, 2023 at 18:40 — jane12
– jane12, Commented Jan 9, 2023 at 18:40

Chris · Accepted Answer · 2023-01-09 18:37:05Z

1

When you return it immediately returns control flow out of the function.

Nothing in the function after that is executed.

As a sidenote, you may want to read the expression in as a string and then execute it. That way you can store it in last_expression rather than just the result of evaling the expression.

answered Jan 9, 2023 at 18:37

Chris

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3 Comments

jane12 Over a year ago

you right, i didn't though about it. i'm stupid :( anyway what do you mean "you may want to read the expression in as a string"?

Chris Over a year ago

You read the expression in as a string and then immediately eval it. As a result, you no longer have access to that input string: just the result of evaling it.

jane12 Over a year ago

do you mean something like this? last_expression = 'nothing' while True: expression = input('Insert an expression: ') if expression == 'done': print('Last expression is: ', last_expression) return last_expression print(eval(expression)) last_expression = eval(expression)

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