c-basics-syntax

C language coding rules based on the C99 and C11 standards, with conventions for project layout, naming, types, headers, and common syntax. C is a compiled programming language often used for systems and embedded software.

In plain words
What is it for?
Use it when creating or reviewing C source files, headers, tests, examples, Makefiles, or CMake projects. It guides naming and the use of standard C features such as fixed-width integers and boolean values.
Why use it?
It gives an agent consistent conventions for writing and organizing C code. This reduces mismatched names, unclear file structure, and avoidable errors in shared projects.

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/wangqiqi/cursor-ai-rules/c-basics-syntax
Clone the repo
git clone --depth 1 https://github.com/wangqiqi/cursor-ai-rules

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 474 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found 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 $0.00000 $0.00474
Opus 5 $0.00000 $0.00237
Sonnet 5 $0.00000 $0.00095
Haiku 4.5 $0.00000 $0.00047

Measured 3d ago against content hash 6386620a0e7c, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

c-basics-syntax 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 3d ago.

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.

.cursor/rules/tech/c-basics-syntax.mdc · 79 lines

What it actually says

C 语言语法规范 (Syntax)

本规则由 @c-basics 引用

项目结构

c_project/
├── Makefile / CMakeLists.txt
├── src/           # 源代码 (main.c, core/, utils/)
├── include/       # 公共头文件
├── tests/         # 测试
├── examples/
└── .clang-format

C99/C11 标准特性

#include <stdbool.h>
#include <stdint.h>

// 固定宽度整数
typedef struct {
    uint32_t id;
    uint8_t flags;
    int64_t timestamp;
    size_t data_size;
} Record;

// bool 与复合字面量
bool validate_record(const Record* record) {
    return record && record->id != 0 && record->data_size > 0;
}

Record create_record(uint32_t id, const char* data) {
    return (Record){
        .id = id,
        .flags = 0x01,
        .timestamp = time(NULL),
        .data_size = strlen(data)
    };
}

// 变长数组 (C99)
void process_data(size_t count, const int data[count]) {
    for (size_t i = 0; i < count; ++i) printf("data[%zu] = %d\n", i, data[i]);
}

命名约定

类型 约定 示例
结构体/枚举 PascalCase UserRecord, ProcessStatus
函数/变量 snake_case process_user_data, buffer_size
常量/宏 SCREAMING_SNAKE_CASE MAX_BUFFER_SIZE
文件静态 前缀 s_ s_connection_count

头文件保护

#ifndef PROJECT_NAME_CONFIG_H
#define PROJECT_NAME_CONFIG_H
// ...
#endif

引用: @c-basics

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. 3d ago First seen · 79 lines · 0 tokens per session scan A 6386620a0e7c

Subscribe to this mod's changes

c-basics-syntax is a cursor rule published in the GitHub repository wangqiqi/cursor-ai-rules (15 stars, last pushed 3mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 474 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.