# Dotnet Pinvoke

Correctly call native (C/C++) libraries from .NET using P/Invoke and LibraryImport.

- Repository: https://github.com/dotnet/skills (5787 stars)
- Category: Testing
- License: MIT
- Last updated: 2026-11-01
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add dotnet/skills --skill dotnet-pinvoke -g -a claude-code -y`
Codex: `npx skills add dotnet/skills --skill dotnet-pinvoke -g -a codex -y`
Cursor: `npx skills add dotnet/skills --skill dotnet-pinvoke -g -a cursor -y`
Gemini CLI: `npx skills add dotnet/skills --skill dotnet-pinvoke -g -a gemini-cli -y`
Claude Code plugin marketplace: `/plugin marketplace add dotnet/skills`

## Description

Correctly call native (C/C++) libraries from .NET using P/Invoke and LibraryImport. Covers function signatures, string marshalling, memory lifetime, SafeHandle, and cross-platform patterns. USE FOR: writing new P/Invoke or LibraryImport declarations, reviewing or debugging existing native interop code, wrapping a C or C++ library for use in .NET, diagnosing crashes, memory leaks, or corruption at the managed/native boundary. DO NOT USE FOR: COM interop, C++/CLI mixed-mode assemblies, or pure managed code with no native dependencies.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# .NET P/Invoke

Calling native code from .NET is powerful but unforgiving. Incorrect signatures, garbled strings, and leaked or freed memory are the most common sources of bugs, all can manifest as intermittent crashes, silent data corruption, or access violations far from the actual defect.

This skill covers both `DllImport` (available since .NET Framework 1.0) and `LibraryImport` (source-generated, .NET 7+). When targeting .NET Framework, always use `DllImport`. When targeting .NET 7+, prefer `LibraryImport` for new code. When native AOT is a requirement, `LibraryImport` is the only option.

## When to Use This Skill

- Writing a new `[DllImport]` or `[LibraryImport]` declaration from a C/C++ header
- Reviewing P/Invoke signatures for correctness (type sizes, calling conventions, string encoding)
- Wrapping an entire C library for use from .NET
- Debugging `AccessViolationException`, `DllNotFoundException`, or silent data corruption at the native boundary
- Migrating `DllImport` declarations to `LibraryImport` for AOT/trimming compatibility
- Diagnosing memory leaks or heap corruption involving native handles or buffers

## Stop Signals

- **Single function?** Map the signature (Steps 1-3), handle strings/memory only if relevant, skip tooling and migration sections.
- **Don't migrate** existing `DllImport` to `LibraryImport` unless the user asks or AOT/trimming is an explicit requirement.
- **Don't recommend CsWin32** unless the target is specifically Win32 APIs.
- **Don't generate callbacks** (Step 8) unless the native API requires function pointers.
- **Review request?** Use the validation checklist, don't rewrite working code.

## Inputs

The rest: https://github.com/dotnet/skills/blob/HEAD/plugins/dotnet-advanced/skills/dotnet-pinvoke/SKILL.md