Hello maintainers

I was trying to use curl to POST something to an api.php when I get the following error:

{"error":{"code":"notoken","info":"The "token" parameter must be set.","*":"See https://wiki.octave.org/wiki/api.php for API usage. Subscribe to the mediawiki-api-announce mailing list at <https://lists.wikimedia.org/mailman/listinfo/mediawiki-api-announce> for notice of API deprecations and breaking changes."}}

My api.php is as follows: https://wiki.octave.org/wiki/api.php

My POSTFIELDs are as follows: username=myusrname&password=mypswd&rememberMe=1&logintoken=b86c77706c772328b4ece0e5dfde31b25af83fcf%2B%5C&loginreturnurl=http%3A%2F%2Fwiki.octave.org%2Fwiki%2Fapi.php 

Note that I'm using libcurl (curl_easy_perform() and alike) for my work. Please help me where I'm going wrong. I'll be really thankful to you. 
Looking forward in anticipation.

Thanks and Regards

Sahil