How to Convert Hexadecimal to Integer?

You can convert a hexadecimal string to an integer using a programming language's built-in functions or by implementing a manual conversion algorithm. The method you choose depends on your specific needs and the environment you're working in.

Using Built-in Functions (Example in C#)

Many programming languages provide built-in functions to easily convert hexadecimal strings to integers. Here's an example using C#:

using System;

public class HexConverter
{
    public static void Main(string[] args)
    {
        string hexValue = "1A"; // Example hexadecimal value
        int decimalValue = Convert.ToInt32(hexValue, 16); // Convert from base-16 (hexadecimal) to integer

        Console.WriteLine($"Hexadecimal value: {hexValue}");
        Console.WriteLine($"Decimal value: {decimalValue}"); // Output: 26
    }
}

Explanation:

• The Convert.ToInt32(string value, int fromBase) method is used. The first argument is the hexadecimal string to convert. The second argument, 16, specifies that the input string is in base-16 (hexadecimal).

Manual Conversion Algorithm

If you need to implement the conversion manually, you can use the following algorithm:

1. Iterate through the hexadecimal string from right to left.

2. For each character:

   • Determine its decimal value:
     • If it's a digit (0-9), its decimal value is the digit itself.
     • If it's a letter (A-F), its decimal value is 10 for 'A', 11 for 'B', 12 for 'C', 13 for 'D', 14 for 'E', and 15 for 'F'. Case does not matter (a-f work the same).

3. Multiply the decimal value by 16 raised to the power of its position (starting from 0 on the right).

4. Add the result to the running total.

Example:

Let's convert the hexadecimal value "1A" manually:

• 'A' (position 0): Decimal value is 10. 10 (16⁰) = 10 1 = 10
• '1' (position 1): Decimal value is 1. 1 (16¹) = 1 16 = 16

Total: 10 + 16 = 26

Python Example

def hex_to_int(hex_string):
    decimal_value = 0
    power = 0
    for char in reversed(hex_string):
        if '0' <= char <= '9':
            digit = int(char)
        elif 'a' <= char <= 'f':
            digit = ord(char) - ord('a') + 10
        elif 'A' <= char <= 'F':
            digit = ord(char) - ord('A') + 10
        else:
            raise ValueError("Invalid hexadecimal character")  #Handles invalid input

        decimal_value += digit * (16 ** power)
        power += 1
    return decimal_value

hex_value = "1A"
decimal_value = hex_to_int(hex_value)
print(f"Hexadecimal value: {hex_value}")
print(f"Decimal value: {decimal_value}")  # Output: 26

Considerations:

• Error Handling: When accepting hexadecimal input from users or external sources, it's crucial to include error handling to validate the input and prevent unexpected behavior. Handle cases where the input string contains invalid characters (characters other than 0-9 and A-F/a-f).
• Case Sensitivity: Built-in functions often handle hexadecimal input case-insensitively (e.g., "1A" is treated the same as "1a"). However, if you're implementing the conversion manually, you might need to handle case sensitivity explicitly, typically by converting the input to uppercase or lowercase.

In summary, using built-in functions is usually the most convenient and efficient way to convert hexadecimal strings to integers. If you need to perform the conversion manually, the outlined algorithm provides a reliable method.