How to edit variable in function, than pass it to another function?

Question

I'am new to python, and i decided to make a simple quiz game. The idea is: Your base health is 100, every wrong answered question is -25 hp. If hp equals 0 you lose.

And here lies the problem. I don't know how to pass the variable from function to a second function (in this case, every question in quiz is a different function)

The problem is that in every function, hp resets to its basic number (100). Sorry if i poorly described my problem but im not very fluent in english.

Already tried to make a function that contains ,,hp = 100", making it global etc. Also tried various stuff with ,,return".

hp = 100

def test1():
    test = input("yes no")
    if test == "yes":
        print("this is hp test")
        print(hp - 25) # should be 100 - 25 = 75
        test2()

    if test == "no":
        print("ok")
        input("dead end")

def test2():
    test2 = input("yes no")
    if test2 == "yes":
        print("this is second hp test")
        print(hp - 25) # should be 75 - 25 = 50 
    if test2 == "no":
        print("ok")
        input("another dead end")

input("start")
test1()

even though it is not a good practice, you can use `global hp` inside each function, and modify its value. — lmiguelvargasf, Sep 19 '19 at 21:06
If you search in your browser for "Python function pass value", you'll find references that can explain this much better than we can manage here. — Prune, Sep 19 '19 at 21:11
It seems to me that you're expecting `print(hp - 25)` to change the value stored in `hp`. To do that, you have to assign a new value to `hp`, something like `hp = hp - 25` — Steve Archer, Sep 19 '19 at 21:28

lmiguelvargasf · Answer 1 · 2019-09-19T21:42:19.963

1

Use global inside each function declartion

hp = 100

def test1():
    global hp # do this in each of your functions
    test = input("yes no")
    if test == "yes":
        print("this is hp test")
        hp -= 25 # which is equivalent to hp = hp - 25
        print(hp) # here just print the updated variable
        test2()

Keep in mind that using global variables is not considered a good practice because it might make your code very hard to debug. You can read more about it here.

edited Sep 19 '19 at 21:42

answered Sep 19 '19 at 21:07

lmiguelvargasf

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will using global cause `print(hp - 25)` to change the value of `hp`? I think that's the issue that the asker is having. – Steve Archer Sep 19 '19 at 21:26
@SteveArcher, no, it won't because you are just printing the variable, you need to add somewhere `hp = hp - 25` if what you want is to decrease that value by 25 or the shortcut `hp -= 25` which is basically the same. – lmiguelvargasf Sep 19 '19 at 21:28
yeah, exactly, so I think advising the use of using global misses the crux of the asker's issue here. They're not having trouble with the scope of `hp`, they're not understanding how variables are assigned values – Steve Archer Sep 19 '19 at 21:30
1

@SteveArcher, I have updated my answer. Now it addresses more appropriately the question. – lmiguelvargasf Sep 19 '19 at 21:43

Yatish Kadam · Answer 2 · 2019-09-19T21:17:25.503

1

I am not really sure what your trying to achieve here. But i would suggest using a class that will allow you to have better control over your variables.

class Game:
  def __init__(self):
      self.hp = 100

  def takeInput(self):
      self.current = input()
      self.computeScore()

  def computeScore(self):
      if self.input ==="Something":
         self.hp -= 25
      if self.checkValidScore():
            self.takeInput()
      else:
         print "game over"

  def checkValidScore(self):
      return self.hp < 0

edited Sep 19 '19 at 21:17

answered Sep 19 '19 at 21:11

Yatish Kadam

454
2
11

1

Notice that this answer uses `-=` to SET the value of the variable. In the question, you're just printing the value of `hp - 25` you're not actually changing the value of `hp` – Steve Archer Sep 19 '19 at 21:25

score 1 · Answer 3 · answered Sep 19 '19 at 21:30

1

The statement print(hp - 25) simply prints the value of hp minus 25. It does not actually modify the value of hp. You probably want:

hp = hp - 25
print(hp)

answered Sep 19 '19 at 21:30

Thyrus017

43
2
11

matheburg · Answer 4 · 2019-09-19T21:34:29.530

Not sure what you want to achieve. If it keeps that simple you could also go in the following direction...

def test1(hp):
    test = input("yes no")
    stop_msg = None
    if test == "yes":
        print("not ok")
        hp -= 25
    elif test == "no":
        print("ok")
        stop_msg = "dead end"
    else:
        raise Exception("Expected input to be 'yes' or 'no'.")
    return hp, stop_msg


def test2(hp):
    test = input("yes no")
    stop_msg = None
    if test == "yes":
        print("'yes' sucks")
        hp -= 25
    elif test == "no":
        print("ok")
        stop_msg = "another dead end"
    else:
        raise Exception("Expected input to be 'yes' or 'no'.")
    return hp, stop_msg


def run_game(hp=100):
    print("start...")
    tests = [test1, test2]
    for test in tests:
        hp, stop_msg = test(hp)
        print("hp: {}".format(hp))
        if stop_msg:
            print(stop_msg)
            return


if __name__ == "__main__":
    run_game()

Remarks:

If you want to implement a more complex decision tree, you could use any simple tree representation.
If you have always the same structure within testX functions, introduce one function with parameters for questions, answer, etc.

How to edit variable in function, than pass it to another function?

4 Answers4