Many years ago, we interviewed a guy from a similar background as yours. He worked for a company that made scientific instruments and he was their software guy. He was looking to become a full time developer.
Back then we gave a C test to applicants. We explained at great length that the purpose of the test was just to see where their knowledge of the language fell. Questions ranged from very basic to quite difficult. Since he was new, we didn't expect him to finish the test or even get half the questions correct.
The recruiter came over about 20 minutes later and said that the applicant was very distraught. He wasn't able to answer any of the questions and he wanted to basically run out the door. The easy questions were very basic: stuff like:
int *p = &i;
*p = 6;
After executing this code, what is the value of i?
Anyway, we calmed him down and said "okay, maybe you aren't ready for a job with us, but we've blocked out the time for an interview and you've blocked out time for an interview, so why not lets us talk to you, see what you know and we can give you some pointers on what we think you should do next to work in the field."
What we found was that, although he understood some syntax of the language, he had absolutely no training in computer science.
So that's where you seem to be. I urge you to learn about computer science. More importantly, pick up a book in data structures and algorithms and study it carefully.
Sorry for the long-winded response.,