SystemH API Reference

Explore classes, methods, and properties across 115 standard .NET types implemented in high-performance, single-header C++. Select any type below or from the sidebar.

⚡ Verified Microbenchmarks SystemH vs C# .NET 10 & Boost Performance

500,000 operations evaluated on Linux x86_64 across dynamic resizing, lookup throughput, and GC pause distributions.

Dictionary ⚡ 2.89x Array ⚡ 12.5x List ⚡ 20x Queue ⚡ 4.6x Stack ⚡ 1.9x LinkedList ⚡ 2.1x vs STL ConcurrentQueue ⚡ 4.1x vs Boost ConcurrentDictionary ⚡ 3.7x vs .NET String ⚡ 3.7x vs .NET Regex ⚡ Linear O(N) • 1.4x vs .NET

Dynamic Insert

2.89x faster

16.05 ms vs 46.32 ms in .NET 10

Insert Throughput

31.1M ops/sec

Flat packed entry buffer

CLR GC Pauses

0 ms GC pause

Deterministic RAII destruction

Tail Pause vs Boost

13.5x lower

2.36 ms vs 31.98 ms in Boost

Platform Architecture Zero Mandatory Dependencies & Modular Features

Core System.h is strictly self-contained (C++17/C++20 standard library only) and respects standard C++ allocators. Optional high-performance subsystems are opt-in via compiler flags.

System.Keywords.h System.MemoryPool.h fetch_dependencies.sh

Feature / Subsystem	Flag / Macro	Underlying Engine	Linux Package	Windows / Embedded
Core BCL Runtime	(Default)	C++17 / C++20 Standard Library	Zero Dependencies	Native Win32 / FreeRTOS (STM32/ESP32) / WASM
RegularExpressions (Regex)	(Core / Built-in)	Native UTF-16 PikeVM (linear-time, ReDoS-safe)	Zero Dependencies	100% Native C++17 (STM32 / ESP32 / Server)
Stream Compression	SYSTEMH_COMPRESSION_ENABLED	zlib (GZip/Deflate) & Google Brotli	zlib1g-dev libbrotli-dev	Win: vcpkg \| ESP32: Built-in miniz ROM
TLS 1.3 & Cryptography	SslStream / Crypto	OpenSSL 3.0+ / Windows CNG / mbedTLS	libssl-dev (-lssl -lcrypto)	Win: bcrypt.dll \| ESP32: ESP-IDF mbedTLS
Database Connectivity	System::Data::Odbc	ODBC 3.x Driver Manager	unixodbc-dev (-lodbc)	Win: odbc32.lib (Windows SDK)

⚡

Important Distinction -- Http.h vs System.h: Http.h is a separate high-concurrency web server module and is not part of core System.h. When HTTP/3 is enabled in Http.h (-D SYSTEMH_HTTP3_ENABLED), it links against the QUIC toolchain (OpenSSL 3.5+ native QUIC, ngtcp2 with ngtcp2_crypto_ossl, and nghttp3). Core System.h does not depend on QUIC.

Microsoft.Win32

1 Types & Interfaces

RegistryKey

System

34 Types & Interfaces

String 3.7x ArgumentException ArgumentNullException ArgumentOutOfRangeException Buffer Console Convert DateTime DateTimeOffset+25 more

System.Collections.Concurrent

3 Types & Interfaces

ConcurrentDictionary<TKey, TValue> 3.7x ConcurrentQueue<T> 4.1x ConcurrentStack<T>

System.Collections.Generic

14 Types & Interfaces