How can I print an output in reverse in Python?

Question

A question is asking me to convert an int into binary, but it also must be in reverse (why!??!?!). After a bunch of tinkering, I was able to get it to print the number in binary. But I can't for the life of me figure out how to make it output in reverse.

The instructions say:

Write a program that takes in a positive integer as input, and outputs a string of 1's and 0's representing the integer in binary.

For an integer x, the algorithm is:

• As long as x is greater than 0
  • Output x modulo 2 (remainder is either 0 or 1)
  • Assign x with x divided by 2

My code is:

x = int(input())

while x > 0:
    x = x//2
    print( x % 2, end = ' ')

Testing with input of 6, I get 1 1 0 but it wants me to output 011.

I even tried putting the answer into a list but when I try to reverse the list, I get an error. List method I tried:

x = int(input())

while x > 0:
    x = x//2
    J = [x % 2]

    L = reversed(J)

    print(L)

output using list method:

<list_reverseiterator object at 0x7f2cd69484f0>
<list_reverseiterator object at 0x7f2cd6948ee0>
<list_reverseiterator object at 0x7f2cd69484f0>

I feel like there's no way this needs some sort of slicing since that method hasn't even been covered yet in the material I'm learning.

Answer 1

You didn't follow the provided algorithm steps in the given order. Swap the statements in the while loop so they align with what was described.

And a small detail: there was no instruction to separate the output with spaces, so you should provide end = '':

x = int(input())

while x > 0:
    print( x % 2, end = '')
    x = x//2

Answer 2

You're reading in the least significant bit first, which results in the output being reversed. You don't need to make an explicit call to reversed().

This produces the desired output:

x = int(input())

result = []
while x > 0:
    result.append(x % 2)
    x = x // 2

# str() transforms each integer to a string.
# We then concatenate them all together
# to get the desired output using ''.join().
print(''.join(str(item) for item in result))

Answer 3

>>> x = 100
>>> res = []
>>> while x > 0:
...   x = x//2
...   J = x%2
...   res.append(J)
...
>>> res
[0, 1, 0, 0, 1, 1, 0]
>>> "".join(str(i) for i in res[::-1])
'0110010'

Answer 4

step1 = input("what number? ")#gets your input
step2 = int(step1) #makes sure it's an int not float
step3 = bin(step2) #converts it to binairy (you method doesn't work for e.g. 7)
step4 = step3.replace("0b", "") #removes 0b from the binairy number
step5 = step4[::-1] #reveses the string
print (step5)

should work or

print(bin(int(input("what number? "))).replace("0b", "")[::-1])

if you want in more compressed

Answer 5

you can use special function of python to convert integer to binary input and the print reverse of binary input by [:1:-1] in J list, so:

integer_input = int(input())                     # input integert number
binary_of_integer_input = bin(integer_input)     # convert integer to binary
print(binary_of_integer_input[2:])               # Print binary of integer input
print(binary_of_integer_input[:1:-1]) # Print reverse binary of integer input

Example:

integer number = 8

binary of input = 1000

reverse of binary = 0001

integer_input = int(input())                     # input integert number
binary_of_integer_input = bin(integer_input)     # convert integer to binary
x = binary_of_integer_input[2:]
J = binary_of_integer_input[:1:-1]
print(x)                                         # Print binary of integer input
print(J)                                         # Print reverse binary of integer input

Answer 6

I am taking This class!!!! Here's a code with materials learned so far that works! For actual Binary. Except reversing a string may not have been mentioned [::-1].

The lab wants answers per strictly that algorithm. So reversed binary and expects it to end with new line.

num = int(input())

while num > 0:
    y =(num % 2)
    print(y, end='')
    num = (num//2)
print()

The Note: The above algorithm outputs the 0's and 1's in reverse order. If interpreted "as Convert to binary using this algorithm but reverse it"

num = int(input("Enter a number"))
string = ""

while num > 0:
    y =str(num % 2)
    string+=y
    num = (num//2)

reverse=string[::-1]
print(reverse)