foreach loop running but not giving results

问题

I am having trouble running a foreach loop. The loop runs without error but gives no output. Can someone tell me what they think might be going on? Many thanks in advance!

Here is the code:

cd "O:\RESEARCH\ikhilko\Subway Big Data project"
local datafiles : dir . files  "*.txt"

foreach file in `datafiles' {
insheet using `file', 
clear
insheet using `file',
drop v9-v43
save date1, replace
}

UPDATE:

Interestingly, the code runs when I just type it into the command line, rather than doing it from the .do file, any idea what might be going on there?

回答1:

It is important to note that local macros are precisely that, i.e. defined and visible only locally.

Locally means within

the same interactive session

or

the same program

or

the same do file (or do file editor contents)

or

the same part of the do file (or ...) executed by selection

Locality is, it seems, biting you here. A local macro defined in one place is not visible in another. A local macro reference will evaluate to missing, i.e. an empty string, if the macro is not visible.

回答2:

Some code for the debugging. display the contents of your local datafiles to see what's going into the loop:

local datafiles : dir . files "*.txt"
display `"`datafiles'"'

local wordx : word 1 of `datafiles'
display `"`wordx'"'

foreach file in `datafiles' {
    display "`file'"
}

(The code does not format well in the comments section.)

来源：https://stackoverflow.com/questions/21613915/foreach-loop-running-but-not-giving-results