How does hex work in c++?

Question

int a = 15;
cout << hex << a;

//output is the small letter f

I'm assuming that hex means hexadecimal.
From the chart, decimal value of 15 gives hexadecimal value of 0F.
Reference chart: https://www.oreilly.com/library/view/ccna-routing-and/9780134466163/app01.html

Question 1:
Is 0F the same as f?
Is there some sort of conversion rule?

Question 2:
Does the second << operator in the last line of code have a special meaning?
Does it mean that the decimal value of variable a is to be converted to a hex value (instead of printing two different things)?

Answer 1

http://www.cplusplus.com/reference/ios/hex/
It doesn't matter what kind F/f will you use. It represent just a 15th position in the hexadecimal system. The value of "a" is converted to hex representation.