CURLOPT_POSTFIELD value not recognized - c++

Question

Thanks to #Mat 's comment i got the solution:
I replaced
curl_easy_setopt(curl, CURLOPT_POSTFIELDS, cQuery);
with
curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, strlen(cQuery));
curl_easy_setopt(curl, CURLOPT_COPYPOSTFIELDS, cQuery);
i am currently struggling at a more or less strange problem which drives me nuts.
I am using the following code to create the value i want to use for CURLOPT_POSTFIELDS to perform a CURL request.
string query;
map<string, string> parameters = resource->GetParameters();
typedef std::map<std::string, std::string>::iterator it_type;
int i = 0;
for (it_type iterator = parameters.begin(); iterator != parameters.end(); iterator++, i++) {
if (i > 0)
query.append("&");
query = query.append(iterator->first).append("=").append(iterator->second);
}
curl_easy_setopt(curl, CURLOPT_POST, true);
const char *cQuery = query.c_str();
cout << cQuery << endl;
cout << "grant_type=client_credentials&scope=default" << endl;
curl_easy_setopt(curl, CURLOPT_POSTFIELDS, cQuery);
The output of both cout are:
grant_type=client_credentials&scope=default
grant_type=client_credentials&scope=default
If I am using the cQuery variable as the value, the server is responding that i didnt specify the grant type.
If I am replacing
curl_easy_setopt(curl, CURLOPT_POSTFIELDS, cQuery);
with
curl_easy_setopt(curl, CURLOPT_POSTFIELDS, "grant_type=client_credentials&scope=default");
it works fine.
My background is more Java and C# related, so i am assuming i missunderstand some of the c++ basics. I am also a newbie on stackoverflow, so if i am doing sth. wrong please let me know.
I am looking forward to your answers. Thank you for your help.

Answer 1

Thanks to #Mat 's comment i got the solution:
I replaced
curl_easy_setopt(curl, CURLOPT_POSTFIELDS, cQuery);
with
curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, strlen(cQuery));
curl_easy_setopt(curl, CURLOPT_COPYPOSTFIELDS, cQuery);