Convert from decimal to binary - python

Question

I'm having an issue with this piece of code I wrote. I'm trying to convert an integer input and print an output with its equivalent in binary base. For example for 5 it should drop an output of '101' however it just prints '10' like if it doesn't take into account the last digit. Please any comments would be greatly appreciated

T = raw_input()
for i in range(0, int(T)):
    n = raw_input()
    dec_num = int(n)
    cnv_bin = ''
    while dec_num//2 > 0:        
        if dec_num%2 == 0:
            cnv_bin += '0'
        else:
            cnv_bin += '1'
        dec_num = dec_num//2
    print cnv_bin[::-1]

I don't know python but if you can convert C code to Python then you can see the link - Decimal to Binary conversion in C — Pankaj Prakash
– Pankaj Prakash, Commented Jan 11, 2016 at 3:08

Mark Tolonen · Accepted Answer · 2016-01-11 01:08:42Z

1

while dec_num//2 > 0:

should be:

while dec_num > 0:

The first time through the loop, 5//2==2, so it continues.
The second time through the loop, 2//2==1, so it continues.
The third time, 1//2==0 and the loop quits without handling the last bit.

Also, you can just do the following to display a number in binary:

print format(dec_num,'b')

Format string version:

print '{0} decimal is {0:b} binary.'.format(5)

edited Jan 11, 2016 at 1:08

answered Jan 11, 2016 at 1:02

Mark Tolonen

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Comments

John Zhang · Accepted Answer · 2016-01-11 02:54:13Z

1

Why not use the build-in function bin()? eg:

bin(5)

output

0b101

If you don't want the prefix(0b), you can exclude it.

bin(5)[2:]

hope to be helpful!

edited Jan 11, 2016 at 2:54

answered Jan 11, 2016 at 1:24

John Zhang

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1 Comment

Andres Vargas Over a year ago

thanks a lot! actually the assignment was to use find the binary equivalent without using the formula...but will keep in mind for future occasions

Linus Sphesihle Madonsela · Accepted Answer · 2021-03-23 14:39:34Z

0

import math
def roundup(n):
    return math.ceil(n)
D = eval(input("Enter The Decimal Value: "))
n = roundup(math.log2(D+1))-1
bi = 0
di = D
qi = 0
i = n
print("Binary Value:",end = " ")
while(i>=0):
    qi = math.trunc(di/2**i)
    bi = qi
    print(bi,end = "")
    di = di - bi*(2**i)
    i = i-1

answered Mar 23, 2021 at 14:39

Linus Sphesihle Madonsela

1

1 Comment

Linus Sphesihle Madonsela Over a year ago

This is a python 3 solution, Enter a Decimal to print a Binary value

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