Else error

[callumagus]

Python Version 2.0
Windows Vista (I know, I know...)

Im very new to python and have only been doing it for two weeks.


print 'Type in lowercase!';
String_Var = raw_input ('Add, Divide, Multiply or Subtract? ');

if 'add' in String_Var:
AddVar1 = raw_input ('Number 1: ');
AddVar2 = raw_input ('Number 2: ');
Add_Var = AddVar1 + AddVar2;
print AddVar1, '+', AddVar2, '=', Add_Var;
else:

if 'subtract' in String_Var:
SubVar1 = raw_input ('Number 1: ');
SubVar2 = raw_input ('Number 2: ');
Sub_Var = SubVar1 - SubVar2;
print SubVar1, '+', SubVar2, '=', Sub_Var;
else:

if 'multiply' in String_Var:
MultiplyVar1 = raw_input ('Number 1: ');
MultiplyVar2 = raw_input ('Number 2: ');
Multpiply_Var = MultiplyVar1 + MultiplyVar2;
print MultiplyVar1, '+', MultiplyVar2, '=', Multiply_Var;
else:

if 'divide' in String_Var:
DivVar1 = raw_input ('Number 1: ');
DivVar2 = raw_input ('Number 2: ');
Div_Var = DivVar1 + DivVar2;
print DivVar1, '+', DivVar2, '=', Div_Var;
else:

print 'Syntax Error.'

I created this code, but it keeps coming up with 'else' syntax error!

[jlm699]

[code=python]print 'Type in lowercase!'
String_Var = raw_input ('Add, Divide, Multiply or Subtract? ')

if 'add' in String_Var:
AddVar1 = raw_input ('Number 1: ')
AddVar2 = raw_input ('Number 2: ')
Add_Var = AddVar1 + AddVar2
print AddVar1, '+', AddVar2, '=', Add_Var
elif 'subtract' in String_Var:
SubVar1 = raw_input ('Number 1: ')
SubVar2 = raw_input ('Number 2: ')
Sub_Var = SubVar1 - SubVar2
print SubVar1, '+', SubVar2, '=', Sub_Var
elif 'multiply' in String_Var:
MultiplyVar1 = raw_input ('Number 1: ')
MultiplyVar2 = raw_input ('Number 2: ')
Multpiply_Var = MultiplyVar1 + MultiplyVar2
print MultiplyVar1, '+', MultiplyVar2, '=', Multiply_Var
elif 'divide' in String_Var:
DivVar1 = raw_input ('Number 1: ')
DivVar2 = raw_input ('Number 2: ')
Div_Var = DivVar1 + DivVar2
print DivVar1, '+', DivVar2, '=', Div_Var
else:
print 'Syntax Error.'[/CODE]

Python doesn't use semicolons or {} brackets for syntax... it's all about the indentation!

[callumagus]

Thank you, the else problem is solved now. What is the command for 'divide'?

[jlm699]

[code=python]while True:
String_Var = raw_input ('Add, Divide, Multiply, Subtract, or Quit? ').lower()

if 'add' in String_Var:
AddVar1 = float(raw_input ('Number 1: '))
AddVar2 = float(raw_input ('Number 2: '))
Add_Var = AddVar1 + AddVar2
print AddVar1, '+', AddVar2, '=', Add_Var
elif 'sub' in String_Var:
SubVar1 = float(raw_input ('Number 1: '))
SubVar2 = float(raw_input ('Number 2: '))
Sub_Var = SubVar1 - SubVar2
print SubVar1, '-', SubVar2, '=', Sub_Var
elif 'mul' in String_Var:
MultiplyVar1 = float(raw_input ('Number 1: '))
MultiplyVar2 = float(raw_input ('Number 2: '))
Multiply_Var = MultiplyVar1 * MultiplyVar2
print MultiplyVar1, '*', MultiplyVar2, '=', Multiply_Var
elif 'div' in String_Var:
DivVar1 = float(raw_input ('Number 1: '))
DivVar2 = float(raw_input ('Number 2: '))
Div_Var = DivVar1 / DivVar2
print DivVar1, '/', DivVar2, '=', Div_Var
elif 'q' in String_Var:
break
else:
print 'Syntax Error.'[/code]

This one's fixed for actual use of numbers... which I didn't notice before.
When you use raw_input it takes the user's input as a string. You need to type cast into either float() or int() in order to perform mathematical operations.

[callumagus]

[code=python]while True:
String_Var = raw_input ('Add, Divide, Multiply, Subtract, or Quit? ').lower()

if 'add' in String_Var:
AddVar1 = float(raw_input ('Number 1: '))
AddVar2 = float(raw_input ('Number 2: '))
Add_Var = AddVar1 + AddVar2
print AddVar1, '+', AddVar2, '=', Add_Var
elif 'sub' in String_Var:
SubVar1 = float(raw_input ('Number 1: '))
SubVar2 = float(raw_input ('Number 2: '))
Sub_Var = SubVar1 - SubVar2
print SubVar1, '-', SubVar2, '=', Sub_Var
elif 'mul' in String_Var:
MultiplyVar1 = float(raw_input ('Number 1: '))
MultiplyVar2 = float(raw_input ('Number 2: '))
Multiply_Var = MultiplyVar1 * MultiplyVar2
print MultiplyVar1, '*', MultiplyVar2, '=', Multiply_Var
elif 'div' in String_Var:
DivVar1 = float(raw_input ('Number 1: '))
DivVar2 = float(raw_input ('Number 2: '))
Div_Var = DivVar1 / DivVar2
print DivVar1, '/', DivVar2, '=', Div_Var
elif 'q' in String_Var:
break
else:
print 'Syntax Error.'[/code]

This one's fixed for actual use of numbers... which I didn't notice before.
When you use raw_input it takes the user's input as a string. You need to type cast into either float() or int() in order to perform mathematical operations.

ok thanks for your help; ive tested the program and it works perfectly now.

[jlm699]

Here's a little more exploration with python for ya:
[CODE=python]
if 'add' in String_Var:
try:
AddVar1 = float(raw_input ('Number 1: '))
AddVar2 = float(raw_input ('Number 2: '))
except:
print 'Invalid input, numbers only please.'
continue
Add_Var = AddVar1 + AddVar2
print AddVar1, '+', AddVar2, '=', Add_Var
[/code]
Play around with this and try entering a string into the number input.

[callumagus]

Here's a little more exploration with python for ya:
[CODE=python]
if 'add' in String_Var:
try:
AddVar1 = float(raw_input ('Number 1: '))
AddVar2 = float(raw_input ('Number 2: '))
except:
print 'Invalid input, numbers only please.'
continue
Add_Var = AddVar1 + AddVar2
print AddVar1, '+', AddVar2, '=', Add_Var
[/code]
Play around with this and try entering a string into the number input.

thanks. so, that will return an aerror message unless they enter a number?

[jlm699]

Yes... when using a try: except: block, you can acheive many things.
Since this is a generic except: it will catch any and all "exceptions ". Sometimes it is good to have a specific exception listed, such as in this case:
[code=python]
except ValueError:
[/code]ValueError is what is thrown when trying toconvert anything non-numerical via int() or float(). You can have multiple except statements, each with a different exception to catch different possible user-errors all followed by a blank "catch-all" except block to catch anything else that might happen. A good way to figure out what kind of error will be generated is to go into the shell, and perform something that you know will throw an exception, such as int('wtf'). ;)
There are also variations on the structure to look into (try, except, else, finally can all be incorporated). Which can provide a variety of error-checking and code balancing.

[callumagus]

The finished product!

import math

while True:
    String_Var = raw_input ('Add, Divide, Multiply, Subtract, Square, Square Root, Index Notation,  or Quit? ').lower()
 
    if 'add' in String_Var:
        try:
            Var1 = float(raw_input ('Number 1: '))
            Var2 = float(raw_input ('Number 2: '))
        except:
            print 'Invalid input, numbers only please.'
            continue
        Var = Var1 + Var2
        print Var1, '+', Var2, '=', Var

    elif 'sub' in String_Var:
        try:
            Var1 = float(raw_input ('Number 1: '))
            Var2 = float(raw_input ('Number 2: '))
        except:
            print 'Invalid input, numbers only please.'
            continue
        Var = Var1 - Var2
        print Var1, '-', Var2, '=', Var

    elif 'div' in String_Var:
        try:
            Var1 = float(raw_input ('Number 1: '))
            Var2 = float(raw_input ('Number 2: '))
        except:
            print 'Invalid input, numbers only please.'
            continue
        Var = Var1 / Var2
        print Var1, '/', Var2, '=', Var

    elif 'mul' in String_Var:
        try:
            Var1 = float(raw_input ('Number 1: '))
            Var2 = float(raw_input ('Number 2: '))
        except:
            print 'Invalid input, numbers only please.'
            continue
        Var = Var1 * Var2
        print Var1, '*', Var2, '=', Var

    elif 'sq' in String_Var:
        try:
            Var1 = float(raw_input ('Number: '))
        except:
            print 'Invalid input, numbers only please.'
            continue
        Var = Var1 * Var1
        print Var1, 'squared =', Var

    elif 'index' in String_Var:
        try:
            Var1 = float(raw_input ('Number: '))
            Var2 = float(raw_input ('To the power of: '))
        except:
            print 'Invalid input, numbers only please.'
            continue
        Var = math.pow(Var1,Var2)
        print Var1, 'to the power of', Var2, '=', Var

    elif 'root' in String_Var:
        try:
            Var1 = float(raw_input ('Number: '))
        except:
            print 'Invalid input, numbers only please.'
            continue
        Var = sqrt (Var1)
        print 'the square root of', Var1, 'is', Var, '.'

        


    elif 'q' in String_Var:
        break

    else:
        print 'Syntax Error.'