64 lines
1.6 KiB
Markdown
64 lines
1.6 KiB
Markdown
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---
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c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
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SPDX-License-Identifier: curl
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Title: CURLOPT_WRITEDATA
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Section: 3
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Source: libcurl
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See-also:
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- CURLOPT_HEADERDATA (3)
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- CURLOPT_READDATA (3)
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- CURLOPT_WRITEFUNCTION (3)
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---
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# NAME
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CURLOPT_WRITEDATA - pointer passed to the write callback
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# SYNOPSIS
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~~~c
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#include <curl/curl.h>
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CURLcode curl_easy_setopt(CURL *handle, CURLOPT_WRITEDATA, void *pointer);
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~~~
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# DESCRIPTION
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A data *pointer* to pass to the write callback. If you use the
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CURLOPT_WRITEFUNCTION(3) option, this is the pointer you get in that
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callback's fourth and last argument. If you do not use a write callback, you
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must make *pointer* a 'FILE *' (cast to 'void *') as libcurl passes this
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to *fwrite(3)* when writing data.
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The internal CURLOPT_WRITEFUNCTION(3) writes the data to the FILE *
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given with this option, or to stdout if this option has not been set.
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If you are using libcurl as a Windows DLL, you **MUST** use a
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CURLOPT_WRITEFUNCTION(3) if you set this option or you might experience
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crashes.
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# DEFAULT
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By default, this is a FILE * to stdout.
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# PROTOCOLS
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Used for all protocols.
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# EXAMPLE
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A common technique is to use the write callback to store the incoming data
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into a dynamically growing allocated buffer, and then this
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CURLOPT_WRITEDATA(3) is used to point to a struct or the buffer to store
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data in. Like in the getinmemory example:
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https://curl.se/libcurl/c/getinmemory.html
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# AVAILABILITY
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Available in all libcurl versions. This option was formerly known as
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CURLOPT_FILE, the name CURLOPT_WRITEDATA(3) was added in 7.9.7.
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# RETURN VALUE
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This returns CURLE_OK.
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