CURLOPT_WRITEDATA(3) Library Functions Manual CURLOPT_WRITEDATA(3)
NAME
CURLOPT_WRITEDATA - pointer passed to the write callback
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_WRITEDATA, void *pointer);
DESCRIPTION
A data pointer to pass to the write callback. If you use the CUR-
LOPT_WRITEFUNCTION(3) option, this is the pointer you get in that call-
back'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 use a CURLOPT_WRITE-
FUNCTION(3) if you set this option or you might experience crashes.
DEFAULT
stdout
PROTOCOLS
This functionality affects all supported protocols
EXAMPLE
A common technique is to use the write callback to store the incoming
data into a dynamically growing allocated buffer, and then this CUR-
LOPT_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/get-
inmemory.html
HISTORY
This option was formerly known as CURLOPT_FILE, the name CURLOPT_WRITE-
DATA(3) was added in 7.9.7.
AVAILABILITY
Added in curl 7.9.7
RETURN VALUE
This returns CURLE_OK.
SEE ALSO
CURLOPT_HEADERDATA(3), CURLOPT_READDATA(3), CURLOPT_WRITEFUNCTION(3)
libcurl 2026-07-12 CURLOPT_WRITEDATA(3)
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