# st: Writing macro contents to a file

 From Roger Newson To statalist@hsphsun2.harvard.edu Subject st: Writing macro contents to a file Date Wed, 25 Jun 2003 17:13:20 +0100

Hello All

A query re writing the contents of a Stata macro to a file. I have been trying to do this by using -file write-, with a file open for writing as an ASCII file, as I have not found a way of writing macro contents to a binary file. For instance, if the macro is a local macro named -linecur-, and the file handle is stored in another local macro named -uhandle-, then I might write

file write uhandle' "linecur'"' _n

to write the contents of the macro -linecur- to the file whose handle is stored in -uhandle-.

There is one problem with this approach, namely that it involves quoting. When Stata quotes a string, it substitutes each occurrence of the substring \\ (double backslash) with a \ (single backslash). This will cause problems if my macro -linecur- contains double backslashes. For instance, if -linecur- contains the string

\textit{Make}&\textit{Weight}\\

then the -file- command shown above will write, to the file, the string

\textit{Make}&\textit{Weight}\

(note that the double slash at the end is now single), and this will cause problems if the file being written is intended to be a LaTeX document.

I therefore decided to try using the -subinstr- macro extended function. If I write

local linecur:subinstr local linecur "\" "\\\\", all
file write uhandle' "linecur'"' _n

then I might expect all single backslashes in the value of -linecur- to be replaced with double backslashes (because the quadruple backslash \\\\ has been reduced by quoting to a double backslash \\), causing -linecur- to contain the string

\\textit{Make}&\\textit{Weight}\\\\

This string should in turn be converted by quoting in the -file- command, which should write to the file the string

\textit{Make}&\textit{Weight}\\

which is what I wanted it to write. Unfortunately, this does not happen. For some reason, under these conditions, Stata writes to the file

\\textit{Make}&\textit{Weight}\\

which I did not want. (Note the extra slash at the beginning of the string.)

Why should this be the case? And does anybody out there know of a better way to output the contents of a macro to a file? I am using Stata 8 under Windows 98 SE. The full log of what I did is listed below.

Best wishes (and thanks in advance)

Roger

*BEGINNING OF STATA LOG - CUT HERE!!!!

. file open uhandle' using nutz.txt,write text replace

. local linecur "\textit{Make}&\textit{Weight}\\\\"

. local lencur:length local linecur

. disp lencur'
31

. local linecur:subinstr local linecur "\" "\\\\", all

. local lencur:length local linecur

. disp lencur'
35

. file write uhandle' "linecur'"' _n

. file close `uhandle'

*END OF STATA LOG - CUT HERE!!!!

--
Roger Newson
Lecturer in Medical Statistics
Department of Public Health Sciences
King's College London
5th Floor, Capital House
42 Weston Street
London SE1 3QD
United Kingdom

Tel: 020 7848 6648 International +44 20 7848 6648
Fax: 020 7848 6620 International +44 20 7848 6620
or 020 7848 6605 International +44 20 7848 6605
Email: roger.newson@kcl.ac.uk
Website: http://www.kcl-phs.org.uk/rogernewson

Opinions expressed are those of the author, not the institution.

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