Introduction to Stata 8 - (GRIPS

15.7. ado-files [U] 20-21, [P] (Programming manual)
An ado-file is a program. Most users will never write programs themselves, but just use
existing programs. If you are a freak, read more in the User's Guide ([U] 20-21) and the
programming manual [P]. Save user-written programs in c:\ado\personal. To see the
locations of all ado-files issue the command sysdir.
The simplest form of an .ado file is a single command or a do-file with a leading program
define command and a terminating end command. There must be a new line after the
terminating end.
Here is an example to demonstrate that creating your own commands is not that impossible.
datetime displays date and time
program define datetime
// c:\ado\personal\datetime.ado. Displays date and time.
display " $S_DATE $S_TIME "
end
Just enter datetime in the command window, and the date and time is displayed:
. datetime
9 Feb 2003 16:54:15
Two ado-files useful for the interaction between Stata and NoteTab are shown in appendix 3.
foreach and forvalues
[P] foreach; forvalues
These commands are documented in the programming manual, and in the online help (whelp
foreach). Also see the FAQ www.stata.com/support/faqs/data/foreach.html. They enable
you to repeat a command for a number of variables or values. The commands can be used not
only in ado-files, but also in do-files and even interactively. Look at the sequence in section
11.1:
foreach Q of varlist q1-q10 {
tabulate `Q' sex
}
Q is a local macro (see [U] 21.3); foreach defines it as a stand-in for the variables q1 to
q10, and the sequence generates ten tabulate commands. The local macro is in effect
only within the braces {} which must be placed as shown.
When referring to the local macro Q it must be enclosed in single quotes: `Q'. In the
manuals single quotes are shown differently; but with a Danish keyboard the opening quote is
` (accent grave), and the ending quote the simple '.
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