On 2013-09-27 15:26, Daniel Stenberg wrote:
On Fri, 27 Sep 2013, Ulf Samuelsson wrote:
Want to create a query with multiple fields, and get the result in a
C++ string
Example: "http://www.myserver.com?field=1&field=2&field=3";
The server need the query to be of the form
"application/x-www-form-urlencoded".
Here's a very simple example showing how to send the POST:
http://curl.haxx.se/libcurl/c/simplepost.html
... and you can combine that with the example showing how to receive
the response back into a memory buffer:
http://curl.haxx.se/libcurl/c/getinmemory.html
Thanks,
That worked.
The merged program is below.
BR
Ulf Samuelsson.
/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2011, Daniel Stenberg, <[email protected]>, et al.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at http://curl.haxx.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
OF ANY
* KIND, either express or implied.
*
***************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <curl/curl.h>
struct MemoryStruct {
char *memory;
size_t size;
};
static size_t
WriteMemoryCallback(void *contents, size_t size, size_t nmemb, void *userp)
{
size_t realsize = size * nmemb;
struct MemoryStruct *mem = (struct MemoryStruct *)userp;
mem->memory = realloc(mem->memory, mem->size + realsize + 1);
if(mem->memory == NULL) {
/* out of memory! */
printf("not enough memory (realloc returned NULL)\n");
return 0;
}
memcpy(&(mem->memory[mem->size]), contents, realsize);
mem->size += realsize;
mem->memory[mem->size] = 0;
return realsize;
}
int main(void)
{
CURL *curl;
CURLcode res;
struct MemoryStruct chunk;
static const char *postthis="Field=1&Field=2&Field=3";
chunk.memory = malloc(1); /* will be grown as needed by the realloc
above */
chunk.size = 0; /* no data at this point */
curl_global_init(CURL_GLOBAL_ALL);
curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, "http://www.myserver.se/";);
/* send all data to this function */
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteMemoryCallback);
/* we pass our 'chunk' struct to the callback function */
curl_easy_setopt(curl, CURLOPT_WRITEDATA, (void *)&chunk);
/* some servers don't like requests that are made without a user-agent
field, so we provide one */
curl_easy_setopt(curl, CURLOPT_USERAGENT, "libcurl-agent/1.0");
curl_easy_setopt(curl, CURLOPT_POSTFIELDS, postthis);
/* if we don't provide POSTFIELDSIZE, libcurl will strlen() by
itself */
curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, (long)strlen(postthis));
/* Perform the request, res will get the return code */
res = curl_easy_perform(curl);
/* Check for errors */
if(res != CURLE_OK) {
fprintf(stderr, "curl_easy_perform() failed: %s\n",
curl_easy_strerror(res));
} else {
/*
* Now, our chunk.memory points to a memory block that is chunk.size
* bytes big and contains the remote file.
*
* Do something nice with it!
*
* You should be aware of the fact that at this point we might
have an
* allocated data block, and nothing has yet deallocated that
data. So when
* you're done with it, you should free() it as a nice application.
*/
// printf("%lu bytes retrieved\n", (long)chunk.size);
printf("%s\n",chunk.memory);
}
/* always cleanup */
curl_easy_cleanup(curl);
if(chunk.memory)
free(chunk.memory);
/* we're done with libcurl, so clean it up */
curl_global_cleanup();
}
return 0;
}
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