Keep a running total(budget)

[mcmxl22]

I am trying to write a budget program. I need to figure out how to keep a running total. How do I update the variable bal via a user input? I have tried while and for loops. This is as close as I can get. 

bal = 0.00

def budget():
    menu = ('1 Set Ballance', '2 Add Transaction', '3 Check Ballance')
    for m in menu:
        print '%s' % m

    what = raw_input('What do you want to do?\n> ').isdigit()

    print bal + what 
    
budget()

Output:
1 Set Ballance
2 Add Transaction
3 Check Ballance
What do you want to do?
> 1
1.0

[nilamo]

.isdigit() converts whatever you type into a bool True/False.  So if you type 2, what will always be True.  When adding a bool to a number, it's silently converted to "1", which is why you're seeing 1.0.

Instead of what = raw_input("???").isdigit(), try:

what = raw_input("???")
if what.isdigit():
   if what == "1":
       bal = float(raw_input("new balance: "))
   elif what == "2":
       # etc...

[mcmxl22]

OK, I totally fudged the code so here is an update:

bal = 0.00
def budget():
    menu = ('1 Set Ballance', '2 Add Transaction', '3 Check Ballance')
    for m in menu:
        print '%s' % m
 
    what = raw_input('What do you want to do?\n> ')
 
    if what in {'1'}:
        enter = input('Enter amount.\n> ')
        print enter + bal 
    
budget()

How do I permanently change the value of bal ?

Output:
1 Set Ballance
2 Add Transaction
3 Check Ballance
What do you want to do?
> 1
Enter amount.
> 200
200.0

[nilamo]

A single equal sign assigns values.

enter = float(raw_input('enter amount'))
bal = enter # bal is now permanently set