How To Save Load to Hard Disc Drive C#

Questions & Answers
1

using Unity 4.0.1,

Windows 7

C#

I’ve found this but when I give in first code I start getting errors

Assets/Scripts/Class/SaveData.cs(13,18): error CS0535: `SaveData' does not implement interface member `System.Runtime.Serialization.ISerializable.GetObjectData(System.Runtime.Serialization.SerializationInfo, System.Runtime.Serialization.StreamingContext)'

than if I modify it a bit - following his path don’t know why that error go away but still…

using UnityEngine;
using System.Collections;

using System.Text;
//using http://System.IO;
using System.Runtime.Serialization.Formatters.Binary;

using System;
using System.Runtime.Serialization;
using System.Reflection;



[Serializable ()]
public class SaveData : ISerializable {
public bool foundGem1 = false;
public float score = 42;
public int levelReached = 3;

	public SaveData (SerializationInfo info, StreamingContext ctxt){
		//Get the values from info and assign them to the appropriate properties
		foundGem1 = (bool)info.GetValue("foundGem1", typeof(bool));
		score = (float)info.GetValue("score", typeof(float));
		
		levelReached = (int)info.GetValue("levelReached", typeof(int));
	}
	
	//Serialization function.
	
	public void GetObjectData (SerializationInfo info, StreamingContext ctxt)
	{
	
		info.AddValue("foundGem1", (foundGem1));
		info.AddValue("score", score);
		info.AddValue("levelReached", levelReached);
	}
	public void Save () {

		SaveData data = new SaveData ();
	
		Stream stream = File.Open("MySavedGame.game", FileMode.Create);
		BinaryFormatter bformatter = new BinaryFormatter();
		bformatter.Binder = new VersionDeserializationBinder();
		Debug.Log ("Writing Information");
		bformatter.Serialize(stream, data);
		stream.Close();
	}

	public void Load () {

		SaveData data = new SaveData ();
		Stream stream = File.Open("MySavedGame.gamed", FileMode.Open);
		BinaryFormatter bformatter = new BinaryFormatter();
		bformatter.Binder = new VersionDeserializationBinder();
		Debug.Log ("Reading Data");
		data = (SaveData)bformatter.Deserialize(stream);
		stream.Close();
	}
	
public sealed class VersionDeserializationBinder : SerializationBinder{
		public override Type BindToType( string assemblyName, string typeName ){
			if ( !string.IsNullOrEmpty( assemblyName ) && !string.IsNullOrEmpty( typeName ) ){
				Type typeToDeserialize = null;
				
				assemblyName = Assembly.GetExecutingAssembly().FullName;
				// The following line of code returns the type.
				typeToDeserialize = Type.GetType( String.Format( "{0}, {1}", typeName, assemblyName ) );
				return typeToDeserialize;
			}
			return null;
		}
	}
}

and now I’m getting errors:

Assets/Scripts/Class/SaveData.cs(41,17): error CS0246: The type or namespace name `Stream' could not be found. Are you missing a using directive or an assembly reference?

and for the last class inside class I thought it would be wrong but it seems it’s not as I get no errors so I’m even more confused as it seems I did steps correctly

I basically puted all in on bottom of each

I really don’t understand 5% of this code

is it really necessary to write 3 pages just to save 1 int on HDD if not can someone show me simpler code how to save data on HDD so I could read write on it

3

Serialization is ment to provide a more or less type safe way to save arbitrary classes to a file and read them back in. If you have complex classes it can get very messy if you save things “manually” to a file. If the data you want to save isn’t that complex you can simply use a BinaryWriter / Reader:

    // C#
    int someValue = 4;
    
    void SaveData()
    {
        using(var writer = new BinaryWriter(File.OpenWrite("FileName")))
        {
            writer.Write(someValue);
            writer.Close();
        }
    }
    
    void LoadData()
    {
        using(var reader = new BinaryReader(File.OpenRead("FileName")))
        {
            someValue = reader.ReadInt32();
            reader.Close();
        }
    }

You need of course the namespace System.IO which contains any classes involved with file IO (input / output).

Just a little warning:
If you use this method to save binary data to a file it looses it’s type. The binary data is just a stream of bytes. That’s why it’s important to read the exact same data that you have written. The Write method accepts a lot different types and it depends on the type you pass to the function what is actually written to the file.

The “normal” int-type is actually an int32. That means one int needs 32 bits (or 4 bytes) of memory. When you read the data back in you have to use the correct function which returns the exact type you’ve written.

2

If you just have a small amount of data to save, I would recomment using the built-in PlayerPrefs class.