QuandlAPI_C

Quandl API (C/C++) is developed to download numeric data from quandl.com, making it easy for those C/C++ developers.

The API is encapsulated within a header file: 1) quandl (windows).h for the Windows environment; or 2) quandl (linux).h for the Linux environment.

It is reccommended that users sign up on http://www.quandl.com/users/sign_up, to obtain an authentication token for downloading increased volume of data per day.

1.After downloading the right header file, please include it in your code by:

//The name by default is quandl (windows).h / quandl (linux).h. 
//You can change it to quandl.h as follows if you like.
//You might also put a full directory depending on the location of the header, e.g.: "#include "C:\Users\MyName\Desktop\API\quandl (windows).h"
#include "quandl.h"

2.Now you can verify your account by by following command. This step can be skipped if you don't have an token or your don't want to use it.

//to register with the authentication token denote by the string "code".
quandl::auth(code);

3.Then you can download the csv file by specifying the Quandl code.

//to download the csv file defined by the quandlcode of a stock
quandl::get(quandlcode);

Alternatively, you can set your preferred values for the available parameters by:

//to download the file specified by eight parameters:
//quandlcode -- quandl code for a stock;
//order -- "asc" / "desc";
//StartDate -- in the format of YYYY-MM-DD, the date from which prices are recorded; 
//EndDate -- in the format of YYYY-MM-DD, the date until prices are recorded;
//transformation -- "cummul" / "diff" / "rdiff" / "normalize" / "cumulative";
//collapse -- "daily" / "weekly" / "monthly" / "quarterly" / "annual";
//rows  -- the number of rows to record;
//type  -- the type of downloaded files ("csv" / "json" / "xml" );
quandl::get(quandlcode, order, StartDate, EndDate, transformation, collapse, rows, type); 

A case study: download the stock price of TENCENT HOLDINGS LTD (TCTZF). The quandlcode is GOOG/PINK_TCTZF. Then you might write the following code:

//#include "quandl (windows).h"
int main() {
    quandl ql;
    ql.auth("<code>"); // Replace <code> with your own token.
    ql.get("GOOG/PINK_TCEHY");
    return 0;
}

Please visit http://www.quandl.com/help/api to better understand the Quandl API design.