The forward-slash character ‘/’ indicates the beginning of a comment. Actually, it instructs the interpreter to ignore everything from it to the end of the line.
Tip: At least one whitespace character must separate ‘/’ intended to begin a comment from any text to the left of it on a line.
In the following example, no definition of c is seen by the interpreter, so an error occurs.
q)b:1+a:42 / nothing here counts c:6*7 q)c ‘c
Notice the succinct (ahem) format of q errors: a single vertical quote (called “tick” in q-speak) followed by a terse error message. In this case, the error should be interpreted as “Error: c is not recognized.”
The following generates an even more succinct error.
q)a:42/ intended to be a comment ‘
Coding Style Recommendation: The q gods have no need for explanatory error messages or comments since their q code is perfect and self-documenting. Even experienced mortals spend hours poring over cryptic q error messages such as the ones above. Moreover, many mortals eschew comments in misanthropic coding macho. Don't.
Reprinted with the author's permission from: q for Mortals Version 3, An Introduction to Q Programming by Jeffry A. Borror.
©2015 Jeffry A. Borror/ q4m LLC