who knows why it will never be optimal to exercise an american call option on non-dividend stocks prior to maturity, thus american call and european call have same value?
I do.
please explain
I’ve always known those things since my father taught me when I was young.
lol… thank you for answering my question. That’s exactly what I need to know. 
I don’t think it’s part of the exam but it would be interesting to know
You would never exercise an American call early (on a nondivd. Stock) because, the price of the option is priced for volatility and uncertainty. By exercising you would only receive the market price of the stock. Instead of early exercise you would just sell the option and receive the “margin” priced into the call for price uncertainty.