Hexadecimal to Decimal Conversion in Python
Hexadecimal to Decimal Conversion
On this page we will learn how to create a python program for Hexadecimal to Decimal Conversion.
Hexadecimal has numbers in the range of [0, 15] and to achieve so it also uses some characters of alphabets.
Hexadecimal Working :
As discussed in hexadecimal numbers range from 0 to 15 so 0 to 9 are represented same as integer values but after 9 alphabets are used as shown below :
- A = 10
- B = 11
- C = 12
- D = 13
- E = 14
- F = 15
How To Convert From Hexadecimal to Decimal Manually?
For a user input num. This requires you to know ASCII values, please check the ASCII table here
To convert a hexadecimal to a decimal manually, you must start by multiplying the hex number by 16. Then, you raise it to a power of 0 and increase that power by 1 each time according to the hexadecimal number equivalent.
We start from the right of the hexadecimal number and go to the left when applying the powers. Each time you multiply a number by 16, the power of 16 increases.
When converting a C9 hexadecimal to a decimal your work should look something like this:
Example :
- 9 = 9 * (16 ^ 0) = 9
- C = 12 * (16 ^ 1) = 192
Then, we add the results.
- 192 + 9 = 201
| Hexadecimal | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | A | B | C | D | E | F |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Decimal | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
Python Code
def convert(hex):
l = len(hex)
decimal = 0
pos = 0
for i in range(l - 1, -1, -1):
# if given index value is a digit (0 - 9)
if '0' <= hex[i] <= '9':
# if hex[i] is in range '0' - '9'
# can convert string value to its integer value
# by passing it to int() function
digit = int(hex[i])
decimal += digit * pow(16, pos)
pos += 1
# if given index is char in range [A, F]
elif 'A' <= hex[i] <= 'F':
# if hex[i] is in range 'A' - 'F'
# can convert sting value to its int value
# by subtracting 55(Refer Ascii table) as
# ASCII val A: 65 and A must result 10 as value
# to get ASCII value in Python can use ord() function
digit = ord(hex[i]) - 55
decimal += digit * pow(16, pos)
pos += 1
return decimal
hex = "C9"
print("decimal value of", hex, "is", convert(hex))
Output
Decimal value of C9 is 201
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hex_to_dec={‘0′:0,’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}
n=input(‘Enter Hexadecimal Number:’).upper()
x=0
l=len(n)
for ch in n:
l=l-1
x=x+(hex_to_dec[ch]*(16**l))
print(‘Hexadecimal:’,n,’\ndecimal:’,x)