Python Binary Converter

Question

I am new to python and trying to write a binary converter. I want to know if there is a way to check if a value entered is 0 or 1.

Example:

binary = userinput

check to see if the 8 bit numbers entered by the user are all binary numbers.

Answer 1

Try this one:

bin_str = raw_input('Enter a binary number: ')

try:
    bin_num = int(bin_str, 2)
    print "Valid binary number entered. - " + bin_str
except ValueError:
    print "Invalid number entered."

Hope that's what you are looking for.

Answer 2

You can use a conditional statement while looping through all digits of the user input value to check if it's equal to 0 or 1.

Ex.:

num = str(input("Insert binary number: "))

for n in num:
    if n == "0" or n == "1":
        print(n, "is a binary digit!")
    else:
        print(n, "is not a binary digit!")

Code Output:

>>> Insert binary number: 12010104

>>> 1 is a binary digit!
>>> 2 is not a binary digit!
>>> 0 is a binary digit!
>>> 1 is a binary digit!
>>> 0 is a binary digit!
>>> 1 is a binary digit!
>>> 0 is a binary digit!
>>> 4 is not a binary digit!

Now you should ask the user for input until they give a valid response, that in your case, is a user input with 8 digits.

Answer 3

Another option, presuming that you don't want to actually create an integer and use the exception handling mechanism:

all(bit in {"0","1"} for bit in userinput)

Answer 4

Check (8 charachters and only "0" or "1") :

is_binary = bool (
        (len (str (userinput).strip ()) == 8)  
    and all (c in ("0", "1") for c in str (userinput))
    )

If you need only to check value range (0 - 0xFF) without explicit check of 8 digits then you can use the 0b prefix (similar to 0x prefix for hexadecimal) :

try:
    value_str = "0b%s" % userinput
    value_int = int (eval (str (value_str)))
    if value_int >= 0 and value_int <= 0xFF :
        is_binary = True
    else :
        is_binary = False
except Exception, e : 
    is_binary = False
    # print "%s %s" % (e.__class__.__name__, e)

Other helpful functions related to binaries:

>>> bin (5)
'0b101'
>>> chr (65)
'A'
>>>
>>> ord ("A")
65
>>> import struct
>>> struct.pack ("B", 65)
'A'
>>> struct.unpack ("B", "A")
(65,)
>>>