---
name: "CURLINFO_CONN_ID"
section: "3"
platform: "macos"
package: "curl"
version: "166.0.0.0.1"
release: "macOS 26.5"
platforms: ["linux", "macos"]
url: "https://new.carta.tech/CURLINFO_CONN_ID"
---

# CURLINFO\_CONN\_ID(3)

get the ID of the last connection used by the handle

## NAME

CURLINFO\_CONN\_ID - get the ID of the last connection used by the handle

## SYNOPSIS

```
#include <curl/curl.h>
CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_CONN_ID,
                           curl_off_t *conn_id);
```

## DESCRIPTION

Pass a pointer to a *curl\_off\_t* to receive the connection identifier last used by the handle. Stores -1 if there was no connection used.

The connection id is unique among all connections using the same connection cache. This is implicitly the case for all connections in the same multi handle.

## PROTOCOLS

All

## EXAMPLE

```
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
    /* Perform the request */
    res = curl_easy_perform(curl);
    if(!res) {
      curl_off_t conn_id;
      res = curl_easy_getinfo(curl, CURLINFO_CONN_ID, &conn_id);
      if(!res) {
        printf("Connection used: %" CURL_FORMAT_CURL_OFF_T "\n", conn_id);
      }
    }
  }
}
```

## AVAILABILITY

Added in 8.2.0

## RETURN VALUE

Returns CURLE\_OK if the option is supported, and CURLE\_UNKNOWN\_OPTION if not.

## SEE ALSO

[**CURLINFO\_XFER\_ID**(3)](/CURLINFO_XFER_ID/3.md), [**curl\_easy\_getinfo**(3)](/curl_easy_getinfo/3.md), [**curl\_easy\_setopt**(3)](/curl_easy_setopt/3.md)