Json string in libcurl - c

Question

Can I send a Json string using libcurl. I am new to both. Any kind of help would be appreciated. Basically i want to send a Json string using libcurl simple send and receive in C
My code is below:
#include <stdio.h>
#include <string.h>
#include <curl/curl.h>
/* Auxiliary function that waits on the socket. */
static int wait_on_socket(curl_socket_t sockfd, int for_recv, long timeout_ms)
{
struct timeval tv;
fd_set infd, outfd, errfd;
int res;
tv.tv_sec = timeout_ms / 1000;
tv.tv_usec= (timeout_ms % 1000) * 1000;
FD_ZERO(&infd);
FD_ZERO(&outfd);
FD_ZERO(&errfd);
FD_SET(sockfd, &errfd); /* always check for error */
if(for_recv)
{
FD_SET(sockfd, &infd);
}
else
{
FD_SET(sockfd, &outfd);
}
/* select() returns the number of signalled sockets or -1 */
res = select(sockfd + 1, &infd, &outfd, &errfd, &tv);
return res;
}
int main(void)
{
CURL *curl;
CURLcode res;
/* Minimalistic http request */
const char *request = "reactantsJSON={"O=O":{"N":1}}&productsJSON=["O=O","[O]"]&temperature=2273.15&pressure=101.325";
curl_socket_t sockfd; /* socket */
long sockextr;
size_t iolen;
curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, "http://gibbs.sdsu.edu:8080/axis2/services/GibbsMinimization/solveTP");
/* Do not do the transfer - only connect to host */
curl_easy_setopt(curl, CURLOPT_CONNECT_ONLY, 1L);
res = curl_easy_perform(curl);
if(CURLE_OK != res)
{
printf("Error: %s\n", strerror(res));
return 1;
}
/* Extract the socket from the curl handle - we'll need it for waiting.
* Note that this API takes a pointer to a 'long' while we use
* curl_socket_t for sockets otherwise.
*/
res = curl_easy_getinfo(curl, CURLINFO_LASTSOCKET, &sockextr);
if(CURLE_OK != res)
{
printf("Error: %s\n", curl_easy_strerror(res));
return 1;
}
sockfd = sockextr;
/* wait for the socket to become ready for sending */
if(!wait_on_socket(sockfd, 0, 60000L))
{
printf("Error: timeout.\n");
return 1;
}
puts("Sending request.");
/* Send the request. Real applications should check the iolen
* to see if all the request has been sent */
res = curl_easy_send(curl, request, strlen(request), &iolen);
if(CURLE_OK != res)
{
printf("Error: %s\n", curl_easy_strerror(res));
return 1;
}
puts("Reading response.");
/* read the response */
for(;;)
{
char buf[1024];
wait_on_socket(sockfd, 1, 60000L);
res = curl_easy_recv(curl, buf, 1024, &iolen);
if(CURLE_OK != res)
break;
printf("Received %u bytes.\n", iolen);
}
/* always cleanup */
curl_easy_cleanup(curl);
}
return 0;
}
the error I am getting is that it says a ";" is missing in line 40, which is nothing but the json string, even though I ahve a ";" on that line. It looks like to send json string i need to do something, which I am not aware of. Do I need to specify some flags while compiling the code.

Answer 1

const char *request = "reactantsJSON={"O=O":{"N":1}}&productsJSON=["O=O","[O]"]&temperature=2273.15&pressure=101.325";
You need to escape " in your string literal.
const char *request = "reactantsJSON={\"O=O\":{\"N\":1}}&productsJSON=[\"O=O\",\"[O]\"]&temperature=2273.15&pressure=101.325";