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Re: CURLOPT_WRITEFUNCTION issues - warning: curl_easy_setopt expects a curl_write_callback argument

From: Daniel Stenberg via curl-library <>
Date: Fri, 21 Jan 2022 14:11:37 +0100 (CET)

On Fri, 21 Jan 2022, Gavin Henry via curl-library wrote:

> json_t *json = outstream;
> json = json_loadb(buffer, size * nmemb, 0, NULL);
> "The value is never used". I'll leave gcc and clang to sort.

The first statement here is pointless since you discard the contents and
assign it again in the second line, which doesn't look right. I think you
probably want something similar to:

        json_t **json = outstream;
        *json = json_loadb(buffer, size * nmemb, 0, NULL);

Because outside of the callback you pass do:

         json_t *json = 0;
         curl_easy_setopt(curl, CURLOPT_WRITEDATA, &json);

... so that's a pointer to a pointer.

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Received on 2022-01-21