Converting hex to dec (python3)

[lewdicrous]

Spoiler

def main():
    H = input("Please enter a 4-digit positive integer H: ")
    h3,h2,h1,h0 = readHexadecimal(H) # calls the function readHexadecimal
    print("The hexadecimal number is %s" %H)
    dec3,dec2,dec1,dec0 = toDecimal(h3,h2,h1,h0) # calls the function toDecimal
    displayDecimal(dec3,dec2,dec1,dec0) # calls the function displayDecimal

## read the input
# @param the hexadecimal number, H
# @return the digit separated into 4 digits (H=h3,h2,h1,h0)
def readHexadecimal(H):
    h3 = H[0]
    h2 = H[1]
    h1 = H[2]
    h0 = H[3]
    print(h3,h2,h1,h0)
    return h3, h2, h1, h0

## converts the hexadecimal to decimal using positional notation
# @param the 4 digits from readHexadecimal()
# @return the 4 digits converted from hex to dec
def toDecimal(h3,h2,h1,h0):
    dec3 = (int(h3) * 4096)
    dec2 = (int(h2) * 256)
    dec1 = (int(h1) * 16)
    dec0 = (int(h0) * 1)
    return dec3, dec2, dec1, dec0

## print the result from toDecimal()
# @param the 4 converted digits from toDecimal()
def displayDecimal(dec3,dec2,dec1,dec0):
    dec3,dec2,dec1,dec0 = toDecimal(dec3,dec2,dec1,dec0)
    print ("The decimal number is %d" %(dec3+dec2+dec1+dec0)) # adding the 4 digits to complete the conversion
   
main()

 

Hello, I'm trying to convert a number from base 16 (hex) to base 10 (dec) using positional notations but i keep getting the wrong answer, for example, (1111)₁₆ = (4369)₁₀ but when I try it using my program I get 16843009

Where am I going wrong?

I still did not write the necessary codes to convert letters to numbers {"A":10, "B":11...} if you know how to neatly incorporate that into the code then that would be much appreciated.

 

Note:

I know that you can use int() to convert into bases, the question asks me to use positional notations instead.

The integer, H, only consists of hexadecimal digits.

The functions:

• readHexadecimal() reads the integer H
• toDecimal() converts the hexadecimal to decimal
• displayDecimal() prints the decimal value

 

Thank you

[panther420]

31 minutes ago, lewdicrous said:

  Reveal hidden contents

def main():
    H = input("Please enter a 4-digit positive integer H: ")
    h3,h2,h1,h0 = readHexadecimal(H) # calls the function readHexadecimal
    print("The hexadecimal number is %s" %H)
    dec3,dec2,dec1,dec0 = toDecimal(h3,h2,h1,h0) # calls the function toDecimal
    displayDecimal(dec3,dec2,dec1,dec0) # calls the function displayDecimal

## read the input
# @param the hexadecimal number, H
# @return the digit separated into 4 digits (H=h3,h2,h1,h0)
def readHexadecimal(H):
    h3 = H[0]
    h2 = H[1]
    h1 = H[2]
    h0 = H[3]
    print(h3,h2,h1,h0)
    return h3, h2, h1, h0

## converts the hexadecimal to decimal using positional notation
# @param the 4 digits from readHexadecimal()
# @return the 4 digits converted from hex to dec
def toDecimal(h3,h2,h1,h0):
    dec3 = (int(h3) * 4096)
    dec2 = (int(h2) * 256)
    dec1 = (int(h1) * 16)
    dec0 = (int(h0) * 1)
    return dec3, dec2, dec1, dec0

## print the result from toDecimal()
# @param the 4 converted digits from toDecimal()
def displayDecimal(dec3,dec2,dec1,dec0):
    dec3,dec2,dec1,dec0 = toDecimal(dec3,dec2,dec1,dec0)
    print ("The decimal number is %d" %(dec3+dec2+dec1+dec0)) # adding the 4 digits to complete the conversion
   
main()

 

Hello, I'm trying to convert a number from base 16 (hex) to base 10 (dec) using positional notations but i keep getting the wrong answer, for example, (1111)₁₆ = (4369)₁₀ but when I try it using my program I get 16843009

Where am I going wrong?

I still did not write the necessary codes to convert letters to numbers {"A":10, "B":11...} if you know how to neatly incorporate that into the code then that would be much appreciated.

 

Note:

I know that you can use int() to convert into bases, the question asks me to use positional notations instead.

The integer, H, only consists of hexadecimal digits.

The functions:

• readHexadecimal() reads the integer H
• toDecimal() converts the hexadecimal to decimal
• displayDecimal() prints the decimal value

 

Thank you

Quick search on stackoverflow revealed me this: 

Proof:

EDIT: Nevermind, I just reread your post and saw that you cant use int. Give me one sec.

[tikker]

Your mistake is calling toDecimal twice. You call it both in the main function and in the displayDecimal function.

The actual code works fine.

[lewdicrous]

3 minutes ago, tikker said:

Your mistake is calling toDecimal twice. You call it both in the main function and in the displayDecimal function.

The actual code works fine.

didn't actually know that'll fix it.. i stayed up till 8am just trying to figure it out :')

Thank you!

[panther420]

7 minutes ago, lewdicrous said:

didn't actually know that'll fix it.. i stayed up till 8am just trying to figure it out :')

Thank you!

I found a solution to the hexadecimal character mapping problem, but I'm not sure if it's against the rules for the problem you're solving. It's just using int(hX, 16) in the toDecimal method to map the characters:

def toDecimal(h3,h2,h1,h0):
    dec3 = (int(h3, 16) * 4096)
    dec2 = (int(h2, 16) * 256)
    dec1 = (int(h1, 16) * 16)
    dec0 = (int(h0, 16) * 1)
    return dec3, dec2, dec1, dec0

Otherwise a dictionary like you proposed would work fine: 

hex_to_dec = { '1' : 1, '2' : 2, '3' : 3,
               '4' : 4, '5' : 5, '6' : 6,
               '7' : 7, '8' : 8, '9' : 9,
               'A' : 10, 'B' : 11, 'C' : 12,
               'D' : 13, 'E' : 14, 'F' : 15 }

def toDecimal(h3,h2,h1,h0):
    dec3 = (hex_to_dec[h3] * 4096)
    dec2 = (hex_to_dec[h2] * 256)
    dec1 = (hex_to_dec[h1] * 16)
    dec0 = (hex_to_dec[h0] * 1)
    return dec3, dec2, dec1, dec0

 

[lewdicrous]

Thank you @tikker for showing me where I went wrong, it also helped me troubleshoot another question

Spoiler

Solution: removing toDecimal() from displayDecimal()

Thank you @panther420 for providing a clean way of converting the hexadecimal symbols to integers without using a lot of if-statements

Spoiler

hex_to_dec = { '1' : 1, '2' : 2, '3' : 3,
               '4' : 4, '5' : 5, '6' : 6,
               '7' : 7, '8' : 8, '9' : 9,
               'A' : 10, 'B' : 11, 'C' : 12,
               'D' : 13, 'E' : 14, 'F' : 15 }

def toDecimal(h3,h2,h1,h0):
    dec3 = (hex_to_dec[h3] * 4096)
    dec2 = (hex_to_dec[h2] * 256)
    dec1 = (hex_to_dec[h1] * 16)
    dec0 = (hex_to_dec[h0] * 1)
    return dec3, dec2, dec1, dec0

 

 

[tikker]

21 minutes ago, lewdicrous said:

Thank you @tikker for showing me where I went wrong, it also helped me troubleshoot another question

  Reveal hidden contents

Solution: removing toDecimal() from displayDecimal()

Thank you @panther420 for providing a clean way of converting the hexadecimal symbols to integers without using a lot of if-statements

  Hide contents

hex_to_dec = { '1' : 1, '2' : 2, '3' : 3,
               '4' : 4, '5' : 5, '6' : 6,
               '7' : 7, '8' : 8, '9' : 9,
               'A' : 10, 'B' : 11, 'C' : 12,
               'D' : 13, 'E' : 14, 'F' : 15 }

def toDecimal(h3,h2,h1,h0):
    dec3 = (hex_to_dec[h3] * 4096)
    dec2 = (hex_to_dec[h2] * 256)
    dec1 = (hex_to_dec[h1] * 16)
    dec0 = (hex_to_dec[h0] * 1)
    return dec3, dec2, dec1, dec0

 

 

And now for the next challenge: allow inputs of arbitrary length

 

[wasab]

Python libraries are seriously making things like these easy. 

[lewdicrous]

1 hour ago, wasab said:

Python libraries are seriously making things like these easy. 

I know, but the question asks you to use a certain method, positional notation, as I've mentioned at the end of the post