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I tired implementing a history list for developing a calculator in Python earlier. I can't overcome the indentation error it displays right here."

Python

past_calc.append(last_calculation)
 else:
  print("Unrecognized operation")

"

What I have tried:

Python

past_calc=[]
def add(a,b):
  return a+b
  
def subtract(a,b):
  return a-b
  
def multiply (a,b):
  return a*b

def divide(a,b):
  try:
    return a/b
  except Exception as e:
    print(e)
def power(a,b):
  return a**b
  
def remainder(a,b):
  return a%b
  
def history():
    if len(past_calc)==0:
        print("No past calculations to show")
    else:
        for x in range(0,len(past_calc)): 
            print(past_calc[x])
  
def select_op(choice):
  if (choice == '#'):
    return -1
  elif (choice == '$'):
    return 0
  elif(choice=='?'):
      history()
  elif (choice in ('+','-','*','/','^','%')):
    while (True):
      num1s = str(input("Enter first number: "))
      print(num1s)
      if num1s.endswith('$'):
        return 0
      if num1s.endswith('#'):
        return -1
        
      try:
        num1 = float(num1s)
        break
      except:
        print("Not a valid number,please enter again")
        continue
    
    while (True):
      num2s = str(input("Enter second number: "))
      print(num2s)
      if num2s.endswith('$'):
        return 0
      if num2s.endswith('#'):
        return -1
      try:  
        num2 = float(num2s)
        break
      except:
        print("Not a valid number,please enter again")
        continue
    
    result = 0.0
    last_calculation = ""
    if choice == '+':
      result = add(num1, num2)
    elif choice == '-':
      result = subtract(num1, num2)
    elif choice == '*':
      result = multiply(num1, num2)
    elif choice == '/':
      result =  divide(num1, num2)
    elif choice == '^':
      result = power(num1, num2)
    elif choice == '%':
      result = remainder(num1, num2)
    else:
      print("Something Went Wrong")
      
    last_calculation =  "{0} {1} {2} = {3}".format(num1, choice, num2, result) 
    print(last_calculation )
    
past_calc.append(last_calculation)
 else:
  print("Unrecognized operation")
    
while True:
  print("Select operation.")
  print("1.Add      : + ")
  print("2.Subtract : - ")
  print("3.Multiply : * ")
  print("4.Divide   : / ")
  print("5.Power    : ^ ")
  print("6.Remainder: % ")
  print("7.Terminate: # ")
  print("8.Reset    : $ ")
  print("8.History  : ? ")
  
  # take input from the user
  choice = input("Enter choice(+,-,*,/,^,%,#,$,?): ")
  print(choice)
  if(select_op(choice) == -1):
    #program ends here
    print("Done. Terminating")
    exit()

Posted 19-Aug-23 4:19am

F Atheeya

Updated 14-Sep-23 8:28am

Deeksha Shenoy

v2

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OriginalGriff · Accepted Answer · 2023-08-19T05:18:00

Solution 1

Indentation in Python is significant: it controls what is and isn't in a block of code.
All the contiguous code indented by the same amount (or more) is part of teh same code block:

Python

while foo == bar:
    Part of loop
    if (foo + bar == foobar:
        Still part of loop
Not part of loop -0 executed once the loop exits.

So look at your code carefully:

Python

past_calc.append(last_calculation)
 else:
  print("Unrecognized operation")

The first line "pulls the block" right back to the beginning of the line, so there is no if for the else to match up with.

Posted 19-Aug-23 5:18am

OriginalGriff

Comments

F Atheeya 19-Aug-23 11:30am

how can i fix it as for this code ?

OriginalGriff 19-Aug-23 11:55am

Only you can answer that - I have no idea what that else is supposed to be connected to! You wrote the code, you understand it - and only you have any idea what you intended when you wrote it! :laugh:

F Atheeya 19-Aug-23 13:12pm

haha thnx for the solution ..i got it right

OriginalGriff 19-Aug-23 13:39pm

You're welcome!

Richard MacCutchan · Accepted Answer · 2023-08-19T06:03:00

You have the following and the last three lines have the wrong indentation:

Python

    last_calculation =  "{0} {1} {2} = {3}".format(num1, choice, num2, result) 
    print(last_calculation )
    
past_calc.append(last_calculation)
 else:
  print("Unrecognized operation")

They need to be changed to:

Python

....last_calculation =  "{0} {1} {2} = {3}".format(num1, choice, num2, result) 
....print(last_calculation )
....past_calc.append(last_calculation)
..else:
....print("Unrecognized operation")

NOTE: I have used dots to represent spaces, as the formatter is destroying my indentations.