Yes, you should capitalize 'President' when it refers to a specific person ('The President of the United States'). It should be left uncapitalized when it is non-specific (Past presidents have included ... ').
Barack Obama
Barack Obama was the president of the United States.
President Barack Obama.
qwek qwak ... add me sa ym abizhal13 :]] IMPROVED ANSWER : hmm..Barack Obama is the President of the United States of America. Barack Obama is the subject IS is the linking verb and PRESIDENT is the subjective complement like saying barack obama = president
President Barack Obama, is wherever the U.S. needs him to be.
Barack Obama is the president of the United States of America.
Barack Obama. (The President is Barack Obama II.)
Barack Obama ... that was a no brainer :-)
Yes Barack Obama can legally be president.
Donald J. Trump became the President after Barack Obama.
No, Barack Obama is the President of the United States of America.
barack obama