There’s fourth the most important and imho the only important type of comment: a comment which helps understanding why code does what it does when it is not exp

There’s fourth the most important and imho the only important type of comment: a comment which helps understanding why code does what it does when it is not expressed in code itself. E. g. // do two iterations of bubble sort before // falling back two qsort // because 99% of data comes almost sorted This information cannot be obtained by reading function body, thus it should be added to comment.