How do I edit a global variable within a function-CodePudding

I'm new to python and I'm trying to make a small text based game I've listed the amount of health the player has and when I try to edit the variable within a function it doesn't change the global variable and when I try to use the global command to define it as a global variable it says the parameter is already a global variable and return also doesn't work?

import random
health = 100
dHealth = 1000

def attack(dHealth):
    attack = random.randint(5,50)
    dHealth = dHealth - attack
    print("You dealth", attack,"damage, the dragon has", dHealth,"health left!")
   
 
attack(dHealth)
print(dHealth)

I wanted the variable to go from 1000 to a number between 995 to 950

CodePudding user response：

The best solution would be not to use it as a global variable. attack should take a value and return the updated value.

import random
health = 100
dHealth = 1000

def attack(monster, health):
    attack = random.randint(5,50)
    health = health - attack
    print("You dealt", attack,"damage, the ", monster, " has", health,"health left!")
    return health
   
 
dHealth = attack("dragon", dHealth)
print(dHealth)

Since attack is, theoretically, no longer specific to the dragon's health, it takes an additional parameter to name the monster being attacked for the call to print.

CodePudding user response：

So you need to specify inside the function that it is the global variable you are trying to change. The code looks something like this:

import random
health = 100
dHealth = 1000

def attack(): # If you pass dHealth here, it only changes the local instance and not 
              # the global one
    global dHealth
    attack = random.randint(5,50)
    dHealth = dHealth - attack
    print("You dealth", attack,"damage, the dragon has", dHealth,"health left!")
   
 
attack()
print(dHealth)

But there is another way, and that is to return a value with the function and assign it to dHealth
Code:

import random
health = 100
dHealth = 1000

def attack(dHealth):
    attack = random.randint(5,50)
    dHealth = dHealth - attack
    print("You dealth", attack,"damage, the dragon has", dHealth,"health left!")
    return dHealth
   
 
dHealth = attack(dHealth) # Here, the returned value of dHealth after 
                          # reduction is assigned to the global variable
                          # so no need to use global variables
print(dHealth)