Python Beginner Help (Calculator)
 

Hello Everyone,

I just joined here hoping to increase my knowledge at python. I have been beginning to learn this language as of yesterday. I have decided that if I really want to increase my knowledge I should start on a project. Well here is my first project, a simple calculator. But for whatever reason when I run the program I'm getting some strange errors... Whatever help and advice you guys could give me would be most appreciated!

#Calculator Test1



print "Calculator:"

print "1)+" 

print "2)-" 

print "3)*" 

print "4)/" 

print " "

print "Select Choice:"

op = input(">")

print " "



#Add

if op == "1":

    print "a + b"

    add1 = input("a:")

    add2 = input("b:")

    print "a + b =", add1+add2



#Sub

if op == "2":

    print "a - b"

    sub1 = input("a:")

    sub2 = input("b:")

    print "a - b =", sub1-sub2



#Multi

if op == "3":

    print "a * b"

    mul1 = input("a:")

    mul2 = input("b:")

    print "a * b =", mul1*mul2



#Div

if op == "4":

    print "a / b"

    div1 = input("a:")

    div2 = input("b:")

    print "a / b =", div1/div2

Thanks,
Inkcoder

Re: Python Beginner Help (Calculator)
 

THe line:

op = input(">")

Takes the input AND evaluates it. That means inputing "1" results in eval("1") which is int("1').
Putting in something like "a" results in the interpreter looking for a name "a" and not finding it.

For the beginning I recommend to use:

op=raw_input(">")

Re: Python Beginner Help (Calculator)
 

First, welcome to the forum!

What 'slate' is really telling you is that input() is for numbers and raw_input() is for strings. Using input() has certain risks since you can also enter a command and it will excute it.

Anyway, if you want to use
op = input(">")
then op will not be a string
and you have to use this if statement
if op == 1:

In the matter of fact, input() allows you to create this very simple calculator, since it evaluates mathematical expressions directly:

print "At the >> prompt enter x op y"

print "where x and y are numbers and op is"

print "-  +  /  *  **  //  for instance 12 * 9"

result = input(">> ")

print "result =", result