Answer by Kyle Siopiolosz for Python int to binary string?

Along a similar line to Yusuf Yazici's answer

def intToBin(n):    if(n < 0):        print "Sorry, invalid input."    elif(n == 0):        print n    else:        result = ""        while(n != 0):            result += str(n%2)            n /= 2        print result[::-1]

I adjusted it so that the only variable being mutated is result (and n of course).

If you need to use this function elsewhere (i.e., have the result used by another module), consider the following adjustment:

def intToBin(n):    if(n < 0):        return -1    elif(n == 0):        return str(n)    else:        result = ""        while(n != 0):            result += str(n%2)            n //= 2            #added integer division        return result[::-1]

So -1 will be your sentinel value indicating the conversion failed. (This is assuming you are converting ONLY positive numbers, whether they be integers or longs).