I don't know why the variable doesn't add up - python-3.x

Question

This is my code so far and i don't know why the variable doesn't add up when i loop the code.
import random
player1=1
player2=1
print("Welcome To My Board Game")
def dice_roll():
dice1=random.randint(1,6)
dice2=random.randint(1,6)
print("Your first roll is",dice1)
print("Your second roll is",dice2)
total_dice=(dice1+dice2)
print("Your total is",total_dice)
print("You moved",total_dice,"spaces, to space",player1+total_dice )
while True:
print("Player 1 Turn")
choice=input("Do you want to roll the dice press r ")
if choice.lower()=="r":
dice_roll()
This is the output of my code
Welcome To My Board Game
Player 1 Turn
Do you want to roll the dice press r r
Your first roll is 6
Your second roll is 5
Your total is 11
You moved 11 spaces, to space 12
Player 1 Turn
Do you want to roll the dice press r r
Your first roll is 4
Your second roll is 5
Your total is 9
You moved 9 spaces, to space 10
Player 1 Turn
Do you want to roll the dice press r
the move space part should add on from the last part

Answer 1

The problem is, dice1, dice2 and total_dice are "destroyed" when the function returns. Those variables are defined within the scope of the function, so they can't be used outside of the function. There are two ways of accessing the variables inside a function:
Change global variables, then read the globals somewhere else. #yi_xiao's answer shows an example of this.
Pass some data in, and return some data.
In general, you should always prefer returning the values instead of mutating (changing) global variables. Using globals variables makes testing harder, and becomes a problem if you need to access the data from more than one thread at a time.
To fix your code, you should return total_dice from dice_roll, and pass the old total in:
import random
player1=1
player2=1
print("Welcome To My Board Game")
# Pass the old total in as total_dice
def dice_roll(total_dice):
dice1=random.randint(1, 6)
dice2=random.randint(1, 6)
print("Your first roll is", dice1)
print("Your second roll is", dice2)
# Increase the running total sum
total_dice += dice1 + dice2
print("Your total is", total_dice)
print("You moved", total_dice, "spaces, to space", player1 + total_dice)
# Return the sum
return total_dice
# Note, in this simple example, sum is actually global.
# In more realistic cases, this would be inside of a function
# instead of being global
sum = 0
while True:
print("Player 1 Turn")
choice = input("Do you want to roll the dice press r ")
if choice.lower() == "r":
# Pass sum to dice_roll
# Reassing sum to the new sum given to us by dice_roll
sum = dice_roll(sum)
Also note, that currently, your loop won't exit, ever. Even if someone types something other than "r", the loop won't exit, you need to tell it to exit. You can either use break, or change from an infinite loop, to something other than while True.

Answer 2

Use global with your var player1, and change it every time.
def dice_roll():
dice1=random.randint(1,6)
dice2=random.randint(1,6)
print("Your first roll is",dice1)
print("Your second roll is",dice2)
total_dice=(dice1+dice2)
print("Your total is",total_dice)
global player1
player1 += total_dice
print("You moved",total_dice,"spaces, to space",player1)
Reference:
The global statement
Python Scopes and Namespaces
Edit:
Go a step further,you can define a class:
import random
class player:
def __init__(self, init_space=1):
self.space = init_space
def dice_roll(self):
dice1 = random.randint(1,6)
dice2 = random.randint(1,6)
print("Your first roll is",dice1)
print("Your second roll is",dice2)
total_dice = (dice1 + dice2)
print("Your total is",total_dice)
self.space += total_dice
print("You moved",total_dice,"spaces, to space", self.space)
player1 = player()
player2 = player()
print("Welcome To My Board Game")
while True:
print("Player 1 Turn")
choice = input("Do you want to roll the dice press r ")
if choice.lower() == "r":
player1.dice_roll()
When there are more players, use class will make things easier.