Why does my While loop Exit?

Question

My comments illustrate my line of reasoning but clearly I've got something wrong. My code just jumps straight to "Your total debt is..."

# Dictionary of Bills
expenses = {'mortgage':[], 'personal':[], 'power':[], 'insurance':[], 'water':[], 'food':[], 'savings':[], 'fuel':[], 'phone':[], 'internet':[], 'credit':[], 'emergencies':[]}
totalDebt = 0
switch = "A"
while switch == switch.isalpha(): # Condition is true, switch is a letter 
for each in expenses: # Iterates through each bill 
 debt = input("%s: "%each) # User input 
 if debt.isdigit(): # checks to make sure they only enter numbers 
 debt = int(debt) # Converts debt to its integer value 
 totalDebt = totalDebt + debt # adds debt to keep a running total. 
 else: # User entered something other than a number 
 print("Only enter digits!") 
print("Your total Debt is: $%i" %totalDebt)
input("Press Enter to continue: ")
print("What is this fortnights Income?")

Answer 1

Your condition doesn't make any sense here:

while switch == switch.isalpha(): # Condition is true, switch is a letter 

switch.isalpha() returns either True or False. switch itself will not be equal to either of those two values, so the whole expression is always going to be False. Remove the equality test:

while switch.isalpha(): # Condition is true, switch is a letter 

Note that your code never actually changes switch, so now your loop is going to continue forever.

• Boogz: It's so obvious now! I knew switch won't change (yet) it was driving me up the wall that it wouldn't work so I hadn't added the change switch clause.
• Boogz: Why does ending the while loop end the for loop that it is nested within?for each in expenses: # Itterates through each bill while switch.isalpha(): # Condition is true, switch is a letter debt = input("%s: "%each) # User input if debt.isdigit(): # checks to make sure they only enter numbers debt = int(debt) # Converts debt to its integer value totalDebt = totalDebt + debt # adds debt to keep a running total. switch = "0" # Condition is False, switch is a number
• Martijn Pieters: @Boogz: You need to set switch back to a letter in the next iteration. switch doesn't magically change bak to 'A' when for loops to the next expense.
• Martijn Pieters: @Boogz: in this context, you probably want to read Asking the user for input until they give a valid response

Answer 2

The While is False

>>> switch
'A'
>>> switch.isalpha()
True
>>> switch == switch.isalpha()
False

You must use switch.isalpha() allown