Spotting an amateur with a small “p”

In my English writing class, we were told when referring to the President of the United States, one should always write the word President using a capital “P”.

As I recall the teacher saying that by using the small “p” you could be writing in reference to the president of a bank, club or company.

The teacher went on to say, however, if in your writings you specifically write the name of that president of the bank, club or company, you would be grammatically correct using the capital “P”.

In other words, the stand alone word “President” refers to only one person in the United States of America wherein the stand alone word "president" does not. I understood from my teacher this is of scrupulous importance in professional writings. In my English classes, as in most English classes at a university, there were students going to be doctors, lawyers who would have to write briefs, people who would be writing as a profession, students eventually writing their dissertations and so forth.

I constantly read post thinking they are written by professional writers, at least they are identified as such, until I see the stand along word “president” referring to President Obama. Ouch!
As always,
BB