Syntax for the * comment

[Julian Reif]

Stata has two types of single-line comments: // and *. The comment // has identical syntax to single-line comments used by, e.g., C and R. However, while * can be placed anywhere on a line, it cannot be placed after code. For example:

* This is a valid comment
   * This is a valid comment
gen var = 3 * This is not a valid comment
gen var = 3 // But this is a valid comment

I am aware of some languages, like Fortran, that require comments at a certain place in the column. Are there examples of other languages that have a single-line comment syntax like Stata's *, which can be placed anywhere on the line but not after code?

[Sven-Kristjan Bormann]

The single-line comment with * cannot be placed after code, because the "*" becomes a multiplication operator and does not work anymore as a sign for the beginning of a comment. It is probably a case of operator overloading. Whether it was good a choice to overload * to use it in two different contexts for two completely distinct functions is probably up to debate.

[William Lisowski]

We should note that only the * comment is valid when used interactively; the // comment and the /* ... */ comment (not mentioned in post #1) are allowed only in programs.

For a more complete discussion, see the output of

help comments

[Nick Cox]

As a comment, rather than a complete answer to the question: when I wrote programs in Fortran IV in the 1970s, then usually called FORTRAN IV, a C character in the first position of a line turned the line into a comment.. A quick Google suggests more flexibility in recent versions.