Python Program to Convert Hexadecimal to Decimal

In the previous article, we have discussed Python Program to Convert Octal to Binary
Given a hexadecimal number and the task is to get the respective decimal number.

Examples:

Example1:

Input:

Given Hexadecimal String = "2C"

Output:

The Decimal value of the given Hexadecimal number { 2C } is: 
44

Example2:

Input:

Given Hexadecimal String = "6AB"

Output:

The Decimal value of the given Hexadecimal number { 6AB } is: 
1707

Program to Convert Hexadecimal to Decimal in Python

Below are the ways to convert the given hexadecimal number into decimal :

Using While Loop (Static Input)
Using While loop (User Input)

Method #1: Using While Loop (Static Input)

Approach:

Import math module using the import keyword.
Give the hexadecimal string as static input and store it in a variable.
Take a variable say ‘rslt_val ‘and initialize its value with 0.
Take another variable say deciml_num and initialize its value with 0.
Calculate the length of the given hexadecimal number and store it in a variable k.
Decrement the value of k by 1 and store it in the same variable k.
Loop from 0 to the length of the given hexadecimal number using the for loop.
Inside the loop, check if the iterator value of the hexadecimal string is greater than or equal to 0 and less than or equal to 9 using the if conditional statement.
If it is true, then convert the iterator value of the hexadecimal string into an integer using the int() function.
Assign its value to the above-initialized rslt_val.
Check if the iterator value of the hexadecimal string is equal to ‘A’ or ‘a’ using the if conditional statement.
If it is true, then assign value 10 to the above-initialized rslt_val.
Check if the iterator value of the hexadecimal string is equal to ‘B’ or ‘b’ using the if conditional statement.
If it is true, then assign value 11 to the above-initialized rslt_val.
Check if the iterator value of the hexadecimal string is equal to ‘C’ or ‘c’ using the if conditional statement.
If it is true, then assign value 12 to the above-initialized rslt_val.
Check if the iterator value of the hexadecimal string is equal to ‘D’ or ‘d’ using the if conditional statement.
If it is true, then assign value 13 to the above-initialized rslt_val.
Check if the iterator value of the hexadecimal string is equal to ‘E’ or ‘e’ using the if conditional statement.
If it is true, then assign value 14 to the above-initialized rslt_val.
Check if the iterator value of the hexadecimal string is equal to ‘F’ or ‘f’ using the if conditional statement.
If it is true, then assign value 15 to the above-initialized rslt_val.
Multiply rslt_val with 16 raised to the power k using math.pow() function and convert it into integer using the int() function.
Add this with the deciml_num and store it in the same variable deciml_num.
Decrease the value of k by 1 and store it in the same variable k.
Print the deciml_num to get the decimal value of the given hexadecimal number.
The Exit of the Program.

Below is the implementation:

# Import math module using the import keyword.
import math
# Give the hexadecimal string as static input and store it in a variable.
hexa_num = "2C"
# Take a variable say 'rslt_val 'and initialize its value with 0.
rslt_val = 0
# Take another variable say deciml_num and initialize its value with 0.
deciml_num = 0
# Calculate the length of the given hexadecimal number and store it in a variable k.
k = len(hexa_num)
# Decrement the value of k by 1 and store it in the same variable k.
k -= 1
print(
    "The Decimal value of the given Hexadecimal number {", hexa_num, "} is: ")
# Loop from 0 to the length of the given hexadecimal number using the for loop.
for itr in range(0, len(hexa_num)):
  # Inside the loop, check if the iterator value of the hexadecimal string is greater than 0
    # and less than 9 using the if conditional statement.
    if hexa_num[itr] >= '0' and hexa_num[itr] <= '9':
     # If it is true, then convert the iterator value of the hexadecimal string into an integer
        # using the int() function.
        # Assign its value to the above-initialized rslt_val.
        rslt_val = (int)(hexa_num[itr])
# Check if the iterator value of the hexadecimal string is equal to 'A' or 'a' using the
# if conditional statement.
# If it is true, then assign value 10 to the above-initialized rslt_val.
    if hexa_num[itr] == 'A' or hexa_num[itr] == 'a':
        rslt_val = 10
# Check if the iterator value of the hexadecimal string is equal to 'B' or 'b' using the
# if conditional statement.
# If it is true, then assign value 11 to the above-initialized rslt_val.
    if hexa_num[itr] == 'B' or hexa_num[itr] == 'b':
        rslt_val = 11
 # Check if the iterator value of the hexadecimal string is equal to 'C' or 'c' using the
# if conditional statement.
# If it is true, then assign value 12 to the above-initialized rslt_val.
    if hexa_num[itr] == 'C' or hexa_num[itr] == 'c':
        rslt_val = 12
# Check if the iterator value of the hexadecimal string is equal to 'D' or 'd' using the
# if conditional statement.
# If it is true, then assign value 13 to the above-initialized rslt_val.
    if hexa_num[itr] == 'D' or hexa_num[itr] == 'd':
        rslt_val = 13
# Check if the iterator value of the hexadecimal string is equal to 'E' or 'e' using the
# if conditional statement.
# If it is true, then assign value 14 to the above-initialized rslt_val.
    if hexa_num[itr] == 'E' or hexa_num[itr] == 'e':
        rslt_val = 14
# Check if the iterator value of the hexadecimal string is equal to 'F' or 'f' using the
# if conditional statement.
# If it is true, then assign value 15 to the above-initialized rslt_val.
    if hexa_num[itr] == 'F' or hexa_num[itr] == 'f':
        rslt_val = 15
# Multiply rslt_val with 16 raised to the power k using math.pow() function and convert it
# into integer using the int() function.
# Add this with the deciml_num and store it in the same variable deciml_num.
    deciml_num = deciml_num+(int)(rslt_val*math.pow(16, k))
# Decrease the value of k by 1 and store it in the same variable k.
    k -= 1
# Print the deciml_num to get the decimal value of the given hexadecimal number.
print(deciml_num)

Output:

The Decimal value of the given Hexadecimal number { 2C } is: 
44

Method #2: Using While loop (User Input)

Approach:

Import math module using the import keyword.
Give the hexadecimal string as user input using the input() function and store it in a variable.
Take a variable say ‘rslt_val ‘and initialize its value with 0.
Take another variable say deciml_num and initialize its value with 0.
Calculate the length of the given hexadecimal number and store it in a variable k.
Decrement the value of k by 1 and store it in the same variable k.
Loop from 0 to the length of the given hexadecimal number using the for loop.
Inside the loop, check if the iterator value of the hexadecimal string is greater than 0 and less than 9 using the if conditional statement.
If it is true, then convert the iterator value of the hexadecimal string into an integer using the int() function.
Assign its value to the above-initialized rslt_val.
Check if the iterator value of the hexadecimal string is equal to ‘A’ or ‘a’ using the if conditional statement.
If it is true, then assign value 10 to the above-initialized rslt_val.
Check if the iterator value of the hexadecimal string is equal to ‘B’ or ‘b’ using the if conditional statement.
If it is true, then assign value 11 to the above-initialized rslt_val.
Check if the iterator value of the hexadecimal string is equal to ‘C’ or ‘c’ using the if conditional statement.
If it is true, then assign value 12 to the above-initialized rslt_val.
Check if the iterator value of the hexadecimal string is equal to ‘D’ or ‘d’ using the if conditional statement.
If it is true, then assign value 13 to the above-initialized rslt_val.
Check if the iterator value of the hexadecimal string is equal to ‘E’ or ‘e’ using the if conditional statement.
If it is true, then assign value 14 to the above-initialized rslt_val.
Check if the iterator value of the hexadecimal string is equal to ‘F’ or ‘f’ using the if conditional statement.
If it is true, then assign value 15 to the above-initialized rslt_val.
Multiply rslt_val with 16 raised to the power k using math.pow() function and convert it into integer using the int() function.
Add this with the deciml_num and store it in the same variable deciml_num.
Decrease the value of k by 1 and store it in the same variable k.
Print the deciml_num to get the decimal value of the given hexadecimal number.
The Exit of the Program.

Below is the implementation:

# Import math module using the import keyword.
import math
# Give the hexadecimal string as user input using the input() function and 
# store it in a variable.
hexa_num = input("Enter some random String Number = ")
# Take a variable say 'rslt_val 'and initialize its value with 0.
rslt_val = 0
# Take another variable say deciml_num and initialize its value with 0.
deciml_num = 0
# Calculate the length of the given hexadecimal number and store it in a variable k.
k = len(hexa_num)
# Decrement the value of k by 1 and store it in the same variable k.
k -= 1
print(
    "The Decimal value of the given Hexadecimal number {", hexa_num, "} is: ")
# Loop from 0 to the length of the given hexadecimal number using the for loop.
for itr in range(0, len(hexa_num)):
  # Inside the loop, check if the iterator value of the hexadecimal string is greater than 0
    # and less than 9 using the if conditional statement.
    if hexa_num[itr] >= '0' and hexa_num[itr] <= '9':
     # If it is true, then convert the iterator value of the hexadecimal string into an integer
        # using the int() function.
        # Assign its value to the above-initialized rslt_val.
        rslt_val = (int)(hexa_num[itr])
# Check if the iterator value of the hexadecimal string is equal to 'A' or 'a' using the
# if conditional statement.
# If it is true, then assign value 10 to the above-initialized rslt_val.
    if hexa_num[itr] == 'A' or hexa_num[itr] == 'a':
        rslt_val = 10
# Check if the iterator value of the hexadecimal string is equal to 'B' or 'b' using the
# if conditional statement.
# If it is true, then assign value 11 to the above-initialized rslt_val.
    if hexa_num[itr] == 'B' or hexa_num[itr] == 'b':
        rslt_val = 11
 # Check if the iterator value of the hexadecimal string is equal to 'C' or 'c' using the
# if conditional statement.
# If it is true, then assign value 12 to the above-initialized rslt_val.
    if hexa_num[itr] == 'C' or hexa_num[itr] == 'c':
        rslt_val = 12
# Check if the iterator value of the hexadecimal string is equal to 'D' or 'd' using the
# if conditional statement.
# If it is true, then assign value 13 to the above-initialized rslt_val.
    if hexa_num[itr] == 'D' or hexa_num[itr] == 'd':
        rslt_val = 13
# Check if the iterator value of the hexadecimal string is equal to 'E' or 'e' using the
# if conditional statement.
# If it is true, then assign value 14 to the above-initialized rslt_val.
    if hexa_num[itr] == 'E' or hexa_num[itr] == 'e':
        rslt_val = 14
# Check if the iterator value of the hexadecimal string is equal to 'F' or 'f' using the
# if conditional statement.
# If it is true, then assign value 15 to the above-initialized rslt_val.
    if hexa_num[itr] == 'F' or hexa_num[itr] == 'f':
        rslt_val = 15
# Multiply rslt_val with 16 raised to the power k using math.pow() function and convert it
# into integer using the int() function.
# Add this with the deciml_num and store it in the same variable deciml_num.
    deciml_num = deciml_num+(int)(rslt_val*math.pow(16, k))
# Decrease the value of k by 1 and store it in the same variable k.
    k -= 1
# Print the deciml_num to get the decimal value of the given hexadecimal number.
print(deciml_num)

Output:

Enter some random String Number = 6AB
The Decimal value of the given Hexadecimal number { 6AB } is: 
1707

Explore more instances related to python concepts from Python Programming Examples Guide and get promoted from beginner to professional programmer level in Python Programming Language.