BitConverter.ToInt16() Method in C#

The BitConverter.ToInt16() method in C# is used to convert two consecutive bytes from a byte array into a 16-bit signed integer (short). This method reads bytes in little-endian format, where the first byte represents the lower-order bits and the second byte represents the higher-order bits.

Syntax

Following is the syntax for the BitConverter.ToInt16() method −

public static short ToInt16(byte[] value, int startIndex);

Parameters

• value − The byte array containing the bytes to convert.

• startIndex − The starting position within the byte array from which to begin reading two bytes.

Return Value

Returns a 16-bit signed integer (short) formed by combining two bytes starting at the specified index.

Example 1: Converting Multiple Byte Pairs

using System;

public class Demo {
    public static void Main() {
        byte[] arr = { 0, 0, 7, 10, 18, 20, 25, 26, 32 };
        Console.WriteLine("Byte Array = {0}", BitConverter.ToString(arr));
        
        for (int i = 1; i < arr.Length - 1; i = i + 2) {
            short res = BitConverter.ToInt16(arr, i);
            Console.WriteLine("\nBytes at index {0}-{1}: {2:X2} {3:X2}", 
                             i, i+1, arr[i], arr[i+1]);
            Console.WriteLine("Result = {0}", res);
        }
    }
}

The output of the above code is −

Byte Array = 00-00-07-0A-12-14-19-1A-20

Bytes at index 1-2: 00 07
Result = 1792

Bytes at index 3-4: 0A 12
Result = 4618

Bytes at index 5-6: 14 19
Result = 6420

Bytes at index 7-8: 1A 20
Result = 8218

Example 2: Simple Byte Pair Conversion

using System;

public class Demo {
    public static void Main() {
        byte[] arr = { 10, 20, 30 };
        Console.WriteLine("Byte Array = {0}", BitConverter.ToString(arr));
        
        short value = BitConverter.ToInt16(arr, 1);
        Console.WriteLine("\nConverting bytes at index 1-2:");
        Console.WriteLine("Byte 1: {0} (0x{0:X2})", arr[1]);
        Console.WriteLine("Byte 2: {0} (0x{0:X2})", arr[2]);
        Console.WriteLine("Result = {0}", value);
    }
}

The output of the above code is −

Byte Array = 0A-14-1E

Converting bytes at index 1-2:
Byte 1: 20 (0x14)
Byte 2: 30 (0x1E)
Result = 7700

How It Works

The method combines two consecutive bytes using little-endian byte order. For bytes b1 and b2 at positions i and i+1, the result is calculated as:

result = b1 + (b2 * 256)

In the second example, bytes 20 (0x14) and 30 (0x1E) produce: 20 + (30 × 256) = 20 + 7680 = 7700.

Conclusion

The BitConverter.ToInt16() method efficiently converts two consecutive bytes from a byte array into a 16-bit signed integer using little-endian format. This method is particularly useful when working with binary data, network protocols, or file formats that store numeric values as byte sequences.