Saving a Dictionary in C# - Serialization?

Question

I am writing a C# application that needs to read about 130,000 (String, Int32) pairs at startup to a Dictionary. The pairs are stored in a .txt file, and are thus easily mod

Answer 1

interesting question. I did some quick tests and you are right - BinaryFormatter is surprisingly slow:

• Serialize 130,000 dictionary entries: 547ms
• Deserialize 130,000 dictionary entries: 1046ms

When I coded it with a StreamReader/StreamWriter with comma separated values I got:

• Serialize 130,000 dictionary entries: 121ms
• Deserialize 130,000 dictionary entries: 111ms

But then I tried just using a BinaryWriter/BinaryReader:

• Serialize 130,000 dictionary entries: 22ms
• Deserialize 130,000 dictionary entries: 36ms

The code for that looks like this:

public void Serialize(Dictionary dictionary, Stream stream)
{
    BinaryWriter writer = new BinaryWriter(stream);
    writer.Write(dictionary.Count);
    foreach (var kvp in dictionary)
    {
        writer.Write(kvp.Key);
        writer.Write(kvp.Value);
    }
    writer.Flush();
}

public Dictionary Deserialize(Stream stream)
{
    BinaryReader reader = new BinaryReader(stream);
    int count = reader.ReadInt32();
    var dictionary = new Dictionary(count);
    for (int n = 0; n < count; n++)
    {
        var key = reader.ReadString();
        var value = reader.ReadInt32();
        dictionary.Add(key, value);
    }
    return dictionary;                
}

As others have said though, if you are concerned about users tampering with the file, encryption, rather than binary formatting is the way forward.