I was a professional programmer before becomming a trader, but all my programming was on mainframes. I am salf-taught in PC programming. I made the decision in 1996 to learn Delphi, because it was about as fast and powerful as C++ but easier to learn. VBasic, version 4, was interpreted, not compiled, making Delphi a very good compromise between the two. The biggest drawback is that there is no demand for Delphi skill. If I were to make the decision today, I would go with VB(dot)Net. My second choice would be Java. The best language to use is usually the one you already know.
Regarding Delphi and IB's API, if you use Ross Hemingway's component (which I highly recommend) previously mentioned in this thread, you won't have to worry about calling conventions. The component comes with a sample application, and support is excellent.
Regarding Delphi and IB's API, if you use Ross Hemingway's component (which I highly recommend) previously mentioned in this thread, you won't have to worry about calling conventions. The component comes with a sample application, and support is excellent.