difficulty with a simple binary adder

Question

I am trying to add 2 binary numbers together using python but i can not figure out how to make a very simple program to do it. This is what i got so far but it is not working:

b=input("what number would you like to add ")
convert1= lambda b: str(int(b, 2))

a=input("what number would you like to add to it ")
convert= lambda a: str(int(a, 2))

c=(b+a)
print (c)
convert=lambda c: str(int(c, 2))
print ("Your binary numbers added together is" + convert(c))

What i mean by not working is if say i try adding 1001 and 1001 it will say the answer is 10011001. Which is wrong.

Can someone please explain why this is not working and any other simple ways of doing this.

What do you mean by "not working"? Could you post your traceback? Is the expected output different from the actual output? — Bach
– Bach, Commented Feb 21, 2014 at 14:10
"What i mean by not working is if say i try adding 1001 and 1001 it will say the answer is 10011001" - that's what happens when adding strings. — Bach
– Bach, Commented Feb 21, 2014 at 14:14
Well can someone please tell me how to correct it? and yes python — Ahmad Naeem
– Ahmad Naeem, Commented Feb 21, 2014 at 14:15

arshajii · Accepted Answer · 2014-02-21 14:23:41Z

2

There is no such thing as "adding in binary" -- when you add two integers, their base is irrelevant. An integer's base is only a convenience when representing it textually. Therefore, what you really want is to add the two integers regularly and then convert that result to binary (and perhaps display the two inputs in binary as well). For instance:

>>> a = 5  # input 1
>>> b = 3  # input 2
>>> 
>>> bin(a)
'0b101'
>>> bin(b)
'0b11'
>>> 
>>> bin(a + b)
'0b1000'

As is, your a and b are strings, so c=(b+a) also produces a string by concatenating a and b.

If you want to read your inputs as binary strings, then you can simply convert them to integers before performing the addition:

>>> a = '101'
>>> b = '011'
>>> 
>>> bin(int(a,2) + int(b,2))
'0b1000'

edited Feb 21, 2014 at 14:23

answered Feb 21, 2014 at 14:18

arshajii

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1 Comment

icedtrees Over a year ago

I believe the poster wants the inputs to be in binary format as well, though. So a would be "1001" string and b would be "1001" string

shad0w_wa1k3r · Accepted Answer · 2014-02-21 14:25:10Z

0

You are trying to add 2 strings! Hence the resultant concatenation.

Edit: Seems that you want the input to be in binary too.

num1 = input("what number would you like to add ")
a = int(num1, 2)

num2 = input("what number would you like to add to it ")
b = int(num2, 2)

ans = bin(a+b)
print("Your addition of numbers, in binary is " + ans)

The above would give sum of 10 & 1 as '0b11'. But, if you want to only print '11', you would have to use

ans = bin(a+b)[2:]

edited Feb 21, 2014 at 14:25

answered Feb 21, 2014 at 14:19

shad0w_wa1k3r

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2 Comments

Ahmad Naeem Over a year ago

question: Are the users support to input a binary or denary number

shad0w_wa1k3r Over a year ago

@AhmadNaeem updated now. If the user inputs a denary/decimal number, use int(num), else for binary, use int(num, 2).

alvas · Accepted Answer · 2014-02-21 14:26:12Z

0

Just use bin(int()), see http://docs.python.org/2/library/functions.html#bin:

x = raw_input("what number would you like to add ")
print x,'is',bin(int(x)),'in binary'
y=raw_input("what number would you like to add to it ")
print y, 'is',bin(int(y)),'in binary'
print
print 'their sum in binary is',bin(int(x+y))

[out]:

$ python test.py
what number would you like to add 123
123 is 0b1111011 in binary
what number would you like to add to it 456
456 is 0b111001000 in binary

their sum in binary is 0b11110001001000000

answered Feb 21, 2014 at 14:26

alvas

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Comments

durron597 · Accepted Answer · 2015-08-14 23:53:22Z

0

It looks like you are adding two strings together; "1001" + "1001" does equal "10011001".

edited Aug 14, 2015 at 23:53

durron597

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answered Feb 21, 2014 at 14:17

Sanjii

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