Trace back output of loops

[Roman von Vorgestern]

Dear Statalist forum,

I need to understand someone else's code, which includes a long loop containing many local variables and temp-files. I do not completely understand what is done by just looking at the code, so it would certainly help to run each line of code step by step and see what each line of code does with my dataset.

However, I am struggling to find commands that allow me to do so within a loop, where everything is executed at once. For instance, I was already using

set trace on

etc., but this just helps me spot the exact line where my error occurs.

So, I am wondering if you might have any tips for commands you usually use when trying to understand single lines of codes of long loops (if something like that exists)?

Many thanks in advance.

[Nick Cox]

You can pepper the code with display statements even down to

di 1 
di 2 
di 3

so that you can see where you got to.

I sometimes use a brutal device of putting say

STOP

at some point in the code so at that point it fails, given an illegal command. Then you can look at your local macros and your dataset to see where you are. Then move that break to later in the code.

It is a common view that Stata debugging is not especially easy, but then there are some good reasons for that.

[Bjarte Aagnes]

and

set traceexpand on

will show the lines after macro expansion

[William Lisowski]

help pause

provides another approach to allowing you to see what your code does with your dataset.

[Roman von Vorgestern]

Thank you all for the tips, I will try them.