CURLOPT_WRITEDATA(3)

CURLOPT_WRITEDATA3

Pointer passed to the write callback

Usage

#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_WRITEDATA, void *pointer);

Overview

A data pointer to pass to the write callback. If you use the CURLOPT_WRITEFUNCTION(3) option, this is the pointer you get in that callback's fourth and last argument. If you do not use a write callback, you must make pointer a 'FILE *' (cast to 'void *') as libcurl passes this to fwrite(3) when writing data.

The internal CURLOPT_WRITEFUNCTION(3) writes the data to the FILE * given with this option, or to stdout if this option has not been set.

If you are using libcurl as a Windows DLL, you must also use CURLOPT_WRITEFUNCTION(3) if you set this option or you might experience crashes.

Default

stdout

Protocols

This functionality affects all supported protocols

Examples

A common technique is to use the write callback to store the incoming data into a dynamically growing allocated buffer, and then this CURLOPT_WRITEDATA(3) is used to point to a struct or the buffer to store data in. Like in the getinmemory example: https://curl.se/libcurl/c/getinmemory.html

Return value

This returns CURLE_OK.

Releases

7 releases since Debian 8 (Jessie); the text changed 6 times.

  1. 8
  2. 9
  3. 10
  4. 11
  5. 12
  6. 13
  7. Arch

History

This option was formerly known as CURLOPT_FILE, the name CURLOPT_WRITEDATA(3) was added in 7.9.7.

Availability

Added in curl 7.9.7

From curl 8.23.0-1 in Arch Linux 2026-11-01. Parsed by carta from the page's man source.