CURLINFO_XFER_ID(3) Introduction to Library Functions CURLINFO_XFER_ID(3)

NAME

CURLINFO_XFER_ID - ID of the transfer

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_XFER_ID,
curl_off_t *xfer_id);

DESCRIPTION

Pass a pointer to a curl_off_t to receive the identifier of the
current/last transfer done with the handle. Stores -1 if no transfer
has been started yet for the handle.

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

PROTOCOLS

This functionality affects all supported protocols

EXAMPLE

int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
CURLcode result;
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");

/* Perform the request */
result = curl_easy_perform(curl);

if(!result) {
curl_off_t xfer_id;
result = curl_easy_getinfo(curl, CURLINFO_XFER_ID, &xfer_id);
if(!result) {
printf("Transfer ID: %" CURL_FORMAT_CURL_OFF_T "\n", xfer_id);
}
}
}
}

AVAILABILITY

Added in curl 8.2.0

RETURN VALUE

curl_easy_getinfo(3) returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error
occurred, see libcurl-errors(3).

SEE ALSO

CURLINFO_CONN_ID(3), curl_easy_getinfo(3), curl_easy_setopt(3)

libcurl 2026-01-08 CURLINFO_XFER_ID(3)