cpp

Guidelines for writing C++, a programming language used for systems, desktop, and performance-sensitive software. They cover naming, type declarations, comments, files, and build-related files such as CMakeLists.txt and Makefiles.

In plain words
What is it for?
Use it when creating or editing C and C++ source files, headers, and build configuration. It guides names for classes, functions, variables, constants, and environment variables.
Why use it?
It reduces inconsistent code, unclear names, undocumented public code, and errors related to C++ rules such as the one-definition rule. Consistent conventions make larger C++ codebases easier to read and review.

Cursor rule for Cursor

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add rules/mitas/cursor-rules/cpp
Clone the repo
git clone --depth 1 https://github.com/mitas/cursor-rules

Made for: Cursor.

Per session 1,091 This file is loaded in full into every session.
When invoked 1,091 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin 95% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.01091 $0.01091
Opus 5 $0.00545 $0.00545
Sonnet 5 $0.00218 $0.00218
Haiku 4.5 $0.00109 $0.00109

Measured yesterday against content hash a0dbe2f79bbc, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

cpp scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

95% identical to cpp-programming-guidelines-cursorrules-prompt-file — 5 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.cursor/rules/cpp.mdc · 135 lines

How it starts

The opening of the file, as written. The whole thing — 135 lines — stays where its author put it; the contents beside it link to each section on GitHub.


description: globs: /*.c,/.cpp,**/.h,/*.hpp,/.cxx,CMakeLists.txt,.cmake,conanfile.txt,Makefil,**/*.cc alwaysApply: false

C++ Programming Guidelines

Basic Principles

  • Use English for all code and documentation.
  • Always declare the type of each variable and function (parameters and return value).
  • Create necessary types and classes.
  • Use Doxygen style comments to document public classes and methods.
  • Don't leave blank lines within a function.
  • Follow the one-definition rule (ODR).

Nomenclature

  • Use PascalCase for classes and structures.
  • Use camelCase for variables, functions, and methods.
  • Use ALL_CAPS for constants and macros.
  • Use snake_case for file and directory names.
  • Use UPPERCASE for environment variables.
  • Avoid magic numbers and define constants.
  • Start each function with a verb.
  • Use verbs for boolean variables. Example: isLoading, hasError, canDelete, etc.
  • Use complete words instead of abbreviations and ensure correct spelling.
    • Except for standard abbreviations like API, URL, etc.
    • Except for well-known abbreviations:
      • i, j, k for loops
      • err for errors
      • ctx for contexts
      • req, res for request/response parameters

Functions

  • Write short functions with a single purpose. Less than 20 instructions.
  • Name functions with a verb and something else.
  • If it returns a boolean, use isX or hasX, canX, etc.
  • If it doesn't return anything (void), use executeX or saveX, etc.
  • Avoid nesting blocks by:
    • Early checks and returns.
    • Extraction to utility functions.
  • Use standard library algorithms (std::for_each, std::transform, std::find, etc.) to avoid function nesting.
  • Use lambda functions for simple operations.
  • Use named functions for non-simple operations.
  • Use default parameter values instead of checking for null or nullptr.
  • Reduce function parameters using structs or classes
    • Use an object to pass multiple parameters.
    • Use an object to return multiple results.
    • Declare necessary types for input arguments and output.
  • Use a single level of abstraction.

Read the full file on GitHub · 135 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 135 lines · 1,091 tokens per session scan A a0dbe2f79bbc

Subscribe to this mod's changes

cpp is a cursor rule published in the GitHub repository mitas/cursor-rules (2 stars, last pushed 1y ago), licensed MIT. It adds 1,091 tokens to every session, about $0.0055 per session on Opus 5. A static security scan graded it A with 0 findings. It is 95% identical to cpp-programming-guidelines-cursorrules-prompt-file, differing in 5 lines, and is treated as a copy.