Convert any object to a byte[]

Use the BinaryFormatter:

byte[] ObjectToByteArray(object obj)
{
    if(obj == null)
        return null;
    BinaryFormatter bf = new BinaryFormatter();
    using (MemoryStream ms = new MemoryStream())
    {
        bf.Serialize(ms, obj);
        return ms.ToArray();
    }
}

Note that obj and any properties/fields within obj (and so-on for all of their properties/fields) will all need to be tagged with the Serializable attribute to successfully be serialized with this.

Like others have said before, you could use binary serialization, but it may produce an extra bytes or be deserialized into an objects with not exactly same data. Using reflection on the other hand is quite complicated and very slow. There is an another solution that can strictly convert your objects to bytes and vise-versa - marshalling:

var size = Marshal.SizeOf(your_object);
// Both managed and unmanaged buffers required.
var bytes = new byte[size];
var ptr = Marshal.AllocHGlobal(size);
// Copy object byte-to-byte to unmanaged memory.
Marshal.StructureToPtr(your_object, ptr, false);
// Copy data from unmanaged memory to managed buffer.
Marshal.Copy(ptr, bytes, 0, size);
// Release unmanaged memory.
Marshal.FreeHGlobal(ptr);

And to convert bytes to object:

var bytes = new byte[size];
var ptr = Marshal.AllocHGlobal(size);
Marshal.Copy(bytes, 0, ptr, size);
var your_object = (YourType)Marshal.PtrToStructure(ptr, typeof(YourType));
Marshal.FreeHGlobal(ptr);

It's noticeably slower and partly unsafe to use this approach for small objects and structs comparing to your own serialization field by field (because of double copying from/to unmanaged memory), but it's easiest way to strictly convert object to byte[] without implementing serialization and without [Serializable] attribute.

checkout this article :http://www.morgantechspace.com/2013/08/convert-object-to-byte-array-and-vice.html

Use the below code

// Convert an object to a byte array
private byte[] ObjectToByteArray(Object obj)
{
    if(obj == null)
        return null;

    BinaryFormatter bf = new BinaryFormatter();
    MemoryStream ms = new MemoryStream();
    bf.Serialize(ms, obj);

    return ms.ToArray();
}

// Convert a byte array to an Object
private Object ByteArrayToObject(byte[] arrBytes)
{
    MemoryStream memStream = new MemoryStream();
    BinaryFormatter binForm = new BinaryFormatter();
    memStream.Write(arrBytes, 0, arrBytes.Length);
    memStream.Seek(0, SeekOrigin.Begin);
    Object obj = (Object) binForm.Deserialize(memStream);

    return obj;
}

Using Encoding.UTF8.GetBytes is faster than using MemoryStream. Here, I am using NewtonsoftJson to convert input object to JSON string and then getting bytes from JSON string.

byte[] SerializeObject(object value) =>Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(value));

Benchmark for @Daniel DiPaolo's version with this version

Method                    |     Mean |     Error |    StdDev |   Median |  Gen 0 | Allocated |
--------------------------|----------|-----------|-----------|----------|--------|-----------| 
ObjectToByteArray         | 4.983 us | 0.1183 us | 0.2622 us | 4.887 us | 0.9460 |    3.9 KB |
ObjectToByteArrayWithJson | 1.548 us | 0.0309 us | 0.0690 us | 1.528 us | 0.3090 |   1.27 KB |