Table of Contents

## Introduction

In this article, we’ll delve into the details of converting a hexadecimal number to its decimal equivalent.

## Understanding Hexadecimal and Decimal

Before we jump into the writing C# program to convert Hexadecimal to Decimal, let’s briefly understand what hexadecimal and decimal systems are.

### Hexadecimal System

Hexadecimal, often referred to as hex, is a base-16 number system. It uses 16 symbols (0-9 and A-F, where A stands for 10, B for 11, and so on).

For example, the hexadecimal number “1A” is equivalent to 26 in decimal.

### Decimal System

Decimal is the standard base-10 number system we use every day. It consists of 10 digits: 0-9. Each digit’s place value is a power of 10.

For example, the decimal number `123`

is calculated as `(1 * 10^2) + (2 * 10^1) + (3 * 10^0)`

.

## C# Program to Convert Hexadecimal to Decimal

Now, let’s move on to the practical example of writing a C# program to convert a hexadecimal number to its decimal equivalent.

```
using System;
class HexToDecimalConverter
{
static void Main()
{
// Input: Hexadecimal number as a string
Console.Write("Enter a Hexadecimal number: ");
string hexInput = Console.ReadLine();
// Convert hex to decimal
int decimalResult = HexToDecimal(hexInput);
// Output: Display the result
Console.WriteLine($"Decimal equivalent: {decimalResult}");
}
static int HexToDecimal(string hex)
{
// Ensure the input is not null or empty
if (string.IsNullOrEmpty(hex))
{
throw new ArgumentException("Hexadecimal input cannot be null or empty.");
}
// Convert hex to decimal using built-in method
int decimalResult = Convert.ToInt32(hex, 16);
return decimalResult;
}
}
```

**Output:**

```
Enter a Hexadecimal number: 1A
Decimal equivalent: 26
```

**Code Explanation:**

- We have created the above program, which takes a hexadecimal input from the user.
- The
`HexToDecimal`

method converts the hex input to decimal using`Convert.ToInt32`

method with base 16. - After converting the Hexadecimal to a Decimal number, the result is displayed to the user.

Let’s break down the hexadecimal number **“1A”** and understand how it is equivalent to **26** in decimal.

**Hexadecimal Number: “1A”**

In the hexadecimal system, each digit represents a power of 16, and the digits can range from 0 to 15. The letters A to F represent the values 10 to 15, respectively.

Breaking down “1A”:

- The rightmost digit ‘A’ represents the decimal value 10.
- The leftmost digit ‘1’ represents the decimal value 1.

Now, let’s calculate the decimal equivalent:

(1×16 ^{1}) + (10×16^{0})

= (1×16) + (10×1)

= 16+10

= 26

Therefore, the hexadecimal number “1A” is equivalent to 26 in decimal. In summary, the ‘1’ contributes 16 to the total, and the ‘A’ contributes 10, resulting in a total of 26 in the decimal system.

**Example 2:**

Here is a **C# Program to Convert Hexadecimal to Decimal** without using any built-in function.

```
using System;
class HexToDecimalConverter
{
static void Main()
{
// Hexadecimal number to be converted
string hexNumber = "1A4";
// Calling the conversion method
int decimalNumber = ConvertHexToDecimal(hexNumber);
// Displaying the result
Console.WriteLine($"Hexadecimal: {hexNumber} \nDecimal: {decimalNumber}");
}
// Method to convert Hexadecimal to Decimal
static int ConvertHexToDecimal(string hexNumber)
{
int decimalNumber = 0;
// Loop through each character in reverse order
for (int i = hexNumber.Length - 1, power = 0; i >= 0; i--, power++)
{
char hexDigit = hexNumber[i];
// Convert hex digit to decimal
int decimalValue = HexDigitToDecimal(hexDigit);
// Add the decimal value to the result
decimalNumber += decimalValue * (int)Math.Pow(16, power);
}
return decimalNumber;
}
// Helper method to convert a single hex digit to decimal
static int HexDigitToDecimal(char hexDigit)
{
if (char.IsDigit(hexDigit))
{
return hexDigit - '0';
}
else
{
// Convert hex letter to decimal value
return char.ToUpper(hexDigit) - 'A' + 10;
}
}
}
```

**Output:**

```
Hexadecimal: ABC
Decimal: 2748
```

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