Probem with using global macro in a string before an underscore

[Pieter Seinen]

Hi statalisters,

I want to use global macro's to refer to folder names, but ran into some unexpected behaviour when using them before the underscore "_" symbol.

Stata seems to ignore the macro that goes before the underscore.

*For example when i do this:

global year "2019"
global month "10"

di "$year_$month"


The console prints: "10" and ignores my call for year.

I want to get to "2019_10".

Could someone explain to me why the first macro gets ignored, and how i could solve it?
Thanks in advance!

[German Rodriguez]

I think the problem may be that the name of the first macro is interpreted as "year_" and there is no such macro, so it displays as blank. You can get around the problem using braces around the macro name:

. global year "2019"

. global month "10"

. di "${year}_${month}"
2019_10

[Nick Cox]

That is,

1. Underscore is certainly allowed in Stata names.

2. Unless otherwise prompted, Stata keeps on going when it thinks it is reading a name and looks for the longest possible legal name.

I see no reason here not to use local macros, as in

local  year "2019"
local  month "10"

di "`year'_`month'"