TheAllenChou String Id Save

String ID library & debugging tools

Project README

String ID

by Ming-Lun "Allen" Chou / / @TheAllenChou / Patreon

String ID (SID) is a tool that converts strings into fix-sized hashed values, commonly used in games for looking up resources. The hash function is chosen to support string concatenation. This project uses FNV-1a hash.

Notable advantages of SIDs over strings:

  • Each SID takes up small constant amount of memory (the underlying integer type).
  • SID comparison is constant-time and typically more efficient than string comparison.
  • Looking up hash tables using SID keys is typically more efficient than using strings.
  • SIDs can be used in switch cases, which is not possible for strings (better efficiency & prettier syntax).
  • Concatenation of prefix SID and suffix string does not require original prefix string (saves memory).

Main disadvantage and solutions:

  • SIDs can be hard to debug, as they are just hashed integers, so it is preferrable to keep a database of string-SID pairs for two-way lookups, as well as a debugger plug-in to translate SIDs into corresponding strings in the watch window.

For more explanations, check out these articles:

This repository contains several projects:

  • sid: Core library (single header file).
  • siddb: SID database library example.
  • sidbot: Local SID database terminal example.
  • sidnet: Networking library for SID server and client.
  • sidserver: Remote SID database server example.
  • sidclient: Remove SID database client example.
  • sidvsdebug: Autoexp add-in for Visual Studio debugging (WIP).
  • unit-test: Library unit tests.

The core library (sid), database library example (siddb), and local database terminal example (sidbot) are platform-agnostic. The rest are targeted for Windows.

To build the projects on Windows, you need:

  • Sublime Text 3 (optional): for convenient premake & build command shortcuts without having to open VS2015
  • Premake 5: for building VS2015 solution & projects
  • Visual Studio 2015: for building binaries

Code Examples

  The SID macro evaluates to a StringId object.
  The SID_VAL macro evaluates to a StringId's underlying raw integer data.
  These macros evaluate to constants at compiled-time if given compile-time constant strings.
  StringId::GerValue() returns a StringId's underlying raw integer data.
  There is intentionally no implicit conversion between StringId and the underlying raw integer type.

// comparison
const StringId sid0 = SID("123");
const StringId sid1 = SID("abc");
ASSERT(sid0 != sid1);

// concatenation
const StringId sid2 = SID("12");
const StringId sid3 = sid2.Concat("3");
ASSERT(sid0 == sid3);

// switch cases
const StringId sid4 = SID("print");
switch (sid4.GetValue())
  case SID_VAL("print"):

  case SID_VAL("draw"):

// asset look-up
Texture* pTexture = g_textureMgr.FindTexture(SID("cloud"));
Open Source Agenda is not affiliated with "TheAllenChou String Id" Project. README Source: TheAllenChou/string-id
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