How to use this reference page

Use reference pages to confirm names, categories, nearby facilities, and the constraints that matter before writing or reviewing code.

Scan the top of the page first to identify the primary types, functions, or algorithm families involved.
Use the nearby-page links when your question is really about a companion header, related algorithm family, or broader subsystem.
Validate tricky behavior with a small compileable example before relying on memory for details like invalidation, ordering, allocation, or lifetime rules.

What header pages are for

Header reference pages are meant to answer a practical question quickly: what this header provides, when to reach for it, and which usage rules are easiest to get wrong.

Start here when you already know roughly which header you need but want a fast operational summary.
Use the example section below as a minimal pattern, then adapt it to your real container, ownership, text, or concurrency workflow.
Jump to broader index pages when you need exhaustive coverage rather than a header-focused summary.

Header Reference: `<semaphore>`

Main facilities

std::counting_semaphore
std::binary_semaphore

What this header is for

Use <semaphore> for permit-based coordination, throttling, and capacity management across threads.

Common patterns

limit parallel access to a fixed number of slots
signal availability of resources or work items
model producer/consumer capacity without exposing full queue internals

Minimal example

#include <semaphore>

int main() {
    // Use this header when you need explicit coordination between tasks.
    return 0;
}

What to verify before relying on this header

How the code will shut down, unblock, or stop safely under cancellation and failure paths.
Which state is shared, which synchronization primitive owns that responsibility, and which memory-ordering assumptions are actually required.
Whether a higher-level facility such as `std::jthread`, `std::future`, or structured task composition would reduce coordination risk.