Problem with function

[Incoming]

Ok, so i've been trying to learn how to use def function. I tried to make a simple archery game based on chance.

import random
loop=1
HP=100
def shot(z):
  if z<50:
   return 50
   print ("Direct Hit")
  elif z >= 50:
   print ("Missed")
while loop==1:
 h=random.random()*100
 n=shot(h)
 choice=raw_input("Pick a shot type(shot, headshot)")
 if choice == "shot":
  HP=100-n
 if HP<=0:
  print ('You win')
  loop=0
 print (HP)
 print (h)

If the shot misses, then this happens

Traceback (most recent call last):
File "/home/usr/Desktop/archery.py", line 15, in <module>
HP=100-n
TypeError: unsupported operand type(s) for -: 'int' and 'NoneType'

I have no idea what I did wrong. Any help would be much appreciated.

[bvdet]

shot() returns None when "z" >= 50, therefore the error. You must return a number. Example:

>>> def x():
... 	print "X"
... 	
>>> 100-x()
X
Traceback (most recent call last):
  File "<interactive input>", line 1, in ?
TypeError: unsupported operand type(s) for -: 'int' and 'NoneType'
>>> def x():
... 	print "X"
... 	return 50
... 
>>> 100-x()
X
50
>>>

[dwblas]

If you are trying to update a score then it would be done like this.

def shot(z, score):
    if z < 50:
        score += 50
        print ("Direct Hit")

    ## z >= 50 is redundant as that is the only possibility
    else:
        print ("Missed")

    return score

score = 0
loop = 1
while loop==1:
    h=random.random()*100
    score=shot(h, score)
## etc.