Error Handling Variables in a calculator program, Error handling numbers are fine
<p>My problem is, as you can see by the title, error handling. Specifically with variables and symbols, those always seem to cause a NameError and shut down the program.</p>

<p>My, well experimented with calculator from a tutorial online, calculator program:</p>

<pre><code>#Calculator Program
#this variable tells the loop whether it should loop or not.
# 1 means loop. anything else means don't loop.
loop = 1
#this variable holds the user's choice in the menu:
choice = 0
while loop == 1:

    #print what options you have

    print "Welcome to calculator.py"
    print "your options are:"
    print " "

    print "1) Addition"
    print "2) Subtraction"
    print "3) Multiplication"
    print "4) Division"
    print "5) Quit calculator.py"
    print " "

    choice = input("Choose your option: ")
    if choice == 1:
        add1 = input("Add this: ")
        add2 = input ("to this: ")
        print add1, "+", add2, "=", add1 + add2
    elif choice == 2:
        sub2 = input("Subtract this: ")
        sub1 = input("from this: ")
        print sub1, "-", sub2, "=", sub1 - sub2
    elif choice == 3:
        mul1 = input("Multiply this: ")
        mul2 = input("with this: ")
        print mul1, "*", mul2, "=", mul1 * mul2
    elif choice == 4:
        div1 = input("Divide this: ")
        div2 = input("by this: ")
        print div1, "/", div2, "=", div1 / div2
    elif choice == a:
        print "Not a valid input, please reconsider."        
    elif choice == 5:
        loop = 0

    else:
        print "Not a valid input, please reconsider."
        print " "

print "Thank you for using calculator.py!"
</code></pre>

<p>The "else" and couple other things are my own.</p>

<p>any feedback would be helpful and future tips for these type of situations would be fantastic. For needing help on this brain stumper you can see i am a beginner.</p>
