C# program to convert binary string to Integer

Converting a binary string to an integer in C# can be accomplished using several methods. The most straightforward approach is using Convert.ToInt32() with base 2, but you can also implement manual conversion for better understanding of the binary-to-decimal process.

Using Convert.ToInt32() Method

The simplest way to convert a binary string to an integer is using the built-in Convert.ToInt32() method with base 2 −

using System;

class Program {
    static void Main() {
        string binaryStr = "1001";
        int result = Convert.ToInt32(binaryStr, 2);
        Console.WriteLine("Binary: " + binaryStr);
        Console.WriteLine("Integer: " + result);
        
        // More examples
        Console.WriteLine("1010 = " + Convert.ToInt32("1010", 2));
        Console.WriteLine("1111 = " + Convert.ToInt32("1111", 2));
    }
}

The output of the above code is −

Binary: 1001
Integer: 9
1010 = 10
1111 = 15

Manual Binary to Integer Conversion

For educational purposes, you can manually convert binary to integer by calculating powers of 2 −

using System;

class Program {
    static void Main() {
        string binaryStr = "1001";
        int result = ManualConvert(binaryStr);
        Console.WriteLine("Binary: " + binaryStr);
        Console.WriteLine("Integer: " + result);
    }
    
    static int ManualConvert(string binaryStr) {
        int result = 0;
        
        for (int i = 0; i < binaryStr.Length; i++) {
            char bit = binaryStr[i];
            
            if (bit == '1') {
                int power = binaryStr.Length - 1 - i;
                result += (int)Math.Pow(2, power);
            }
            else if (bit != '0') {
                throw new ArgumentException("Invalid binary string");
            }
        }
        
        return result;
    }
}

The output of the above code is −

Binary: 1001
Integer: 9

Using LINQ for Conversion

Here's a more concise approach using LINQ −

using System;
using System.Linq;

class Program {
    static void Main() {
        string binaryStr = "1101";
        
        int result = binaryStr
            .Select((bit, index) => bit == '1' ? (int)Math.Pow(2, binaryStr.Length - 1 - index) : 0)
            .Sum();
            
        Console.WriteLine("Binary: " + binaryStr);
        Console.WriteLine("Integer: " + result);
    }
}

The output of the above code is −

Binary: 1101
Integer: 13

Comparison of Methods

Conclusion

Converting binary strings to integers in C# is most efficiently done using Convert.ToInt32(binaryString, 2). Manual conversion helps understand the underlying mathematical process, while LINQ provides a functional programming approach for those who prefer it.