---
name: "nng_ctx_id"
section: "3"
platform: "linux"
package: "libnng-dev"
version: "1.10.1-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/nng_ctx_id"
---

# nng\_ctx\_id(3)

return numeric context identifier

## NAME

nng\_ctx\_id - return numeric context identifier

## SYNOPSIS

```
#include <nng/nng.h>
int nng_ctx_id(nng_ctx c);
```

## DESCRIPTION

The `nng_ctx_id()` function returns a positive identifier for the context *c*, if it is valid. Otherwise it returns `-1`.

**Note**\

A context is considered valid if it was ever opened with `nng_ctx_open()` function. Contexts that are allocated on the stack or statically should be initialized with the macro `NNG_CTX_INITIALIZER` to ensure that they cannot be confused with a valid context before they are opened.

## RETURN VALUES

This function returns the positive value for the context identifier, or `-1` if the context is invalid.

## ERRORS

None.

## SEE ALSO

[nng\_ctx(5)](/nng_ctx/5.md), [nng(7)](/nng/7.md)