C# Program to perform Currency Conversion

Currency conversion is a common programming task that involves multiplying an amount by an exchange rate. In C#, we can create simple currency conversion programs using basic arithmetic operations.

A currency converter takes an amount in one currency and converts it to another currency using the current exchange rate. The formula is: Converted Amount = Original Amount × Exchange Rate.

Syntax

Following is the basic syntax for currency conversion −

double convertedAmount = originalAmount * exchangeRate;

Where variables are declared as −

double originalAmount, convertedAmount, exchangeRate;

Using Simple Currency Conversion

Let's convert 10 US dollars to Indian Rupees (INR) using a fixed exchange rate −

using System;

public class Program {
   public static void Main(string[] args) {
      double usd, inr, exchangeRate;
      
      // Amount in dollars
      usd = 10;
      // Current exchange rate (1 USD = 83 INR approximately)
      exchangeRate = 83;
      // Convert to INR
      inr = usd * exchangeRate;
      
      Console.WriteLine("{0} USD = {1} INR", usd, inr);
   }
}

The output of the above code is −

10 USD = 830 INR

Using Multiple Currency Conversions

This example shows conversion between multiple currencies using different exchange rates −

using System;

public class Program {
   public static void Main(string[] args) {
      double amount = 100;
      
      // Exchange rates (approximate values)
      double usdToInr = 83.0;
      double usdToEur = 0.92;
      double usdToGbp = 0.79;
      
      // Convert USD to other currencies
      double inr = amount * usdToInr;
      double eur = amount * usdToEur;
      double gbp = amount * usdToGbp;
      
      Console.WriteLine("Currency Conversion for {0} USD:", amount);
      Console.WriteLine("INR: {0}", inr);
      Console.WriteLine("EUR: {0}", eur);
      Console.WriteLine("GBP: {0}", gbp);
   }
}

The output of the above code is −

Currency Conversion for 100 USD:
INR: 8300
EUR: 92
GBP: 79

Using Method-Based Currency Converter

A more organized approach using methods for different currency conversions −

using System;

public class CurrencyConverter {
   public static double UsdToInr(double usd) {
      return usd * 83.0;
   }
   
   public static double UsdToEur(double usd) {
      return usd * 0.92;
   }
   
   public static double InrToUsd(double inr) {
      return inr / 83.0;
   }
}

public class Program {
   public static void Main(string[] args) {
      double amount = 50;
      
      Console.WriteLine("Original amount: {0} USD", amount);
      Console.WriteLine("Converted to INR: {0}", CurrencyConverter.UsdToInr(amount));
      Console.WriteLine("Converted to EUR: {0:F2}", CurrencyConverter.UsdToEur(amount));
      
      double inrAmount = 4150;
      Console.WriteLine("\nOriginal amount: {0} INR", inrAmount);
      Console.WriteLine("Converted to USD: {0:F2}", CurrencyConverter.InrToUsd(inrAmount));
   }
}

The output of the above code is −

Original amount: 50 USD
Converted to INR: 4150
Converted to EUR: 46.00

Original amount: 4150 INR
Converted to USD: 50.00

Key Points

• Always use double data type for currency values to handle decimal amounts.

• Exchange rates fluctuate frequently, so use updated rates for accurate conversions.

• Use String.Format() or format specifiers like {0:F2} to limit decimal places.

• Consider creating separate methods or classes for better code organization.

Conclusion

Currency conversion in C# involves simple multiplication using exchange rates. For real-world applications, consider using APIs for live exchange rates and proper error handling for invalid inputs.