Nick and Martin, thank you very much!
Just as Nick pointed, I recognized my confusion was the use of -di-. However, I do need learn the use of -macro- too.
A doubt appears when learning the use of -di-. What is the difference between "" and `""'?
In -di- help,I guess the only difference is the latter allows embedded quotes, am I right?
Additionally, there is a small question below.
. foreach i in a" "b" "c {
2. di `"`i'"'
3. }
a"
b
c
Where is the quote before c. Namely, I think the result should be
a"
b
"c
Thank you again for any help!
Best regards,
Rose.
----- Original Message -----
From: Nick Cox <[email protected]>
To: [email protected]
Subject: Re: AW: st: How to use the marco names?
Date: 2009-8-6 23:47:19
Not so.
First off, a literal string here is one marked as such by " " or `" "'
delimiters.
Second, it is key that the -display- command never sees the text
`level'
as it is a reference to a local macro. Stata replaces the reference to
the macro with its contents _before_ -display- ever gets to work. So,
-display- sees
a b c
and without the " " that is not a literal string.
nICK
[email protected] wrote:
> Nick, thank you for your help, which lets me understand more.
>
> I suddenly think of the following typing,
>
> .local level a b c
>
> . di "`level'"
> a b c
>
> . di `"level"'
> level
>
> . di `level'
> a not found
> r(111);
>
> If -di- is to display literal strings or the contents of the names
> supplied, the results for the above three should be,
>
> `level' // literal string
>
> error // no local name "level",but local name level.
>
> a b c // the contents of the names.
>
>
> Please forgive my ignorance, thank you.
>
> Best regards,
>
> Rose.
>
>
>
>
>
> ----- Original Message -----
> From: Nick Cox <[email protected]>
> To: [email protected]
> Subject: Re: AW: st: How to use the marco names?
> Date: 2009-8-6 22:38:04
>
> In addition to other advice, note that a major issue here is not macros,
> but the use of -display-.
>
> -display- is quite happy to display several things one after another. It
> is also happy to display literal strings or the contents of the names
> supplied. The " " or `" "' are essential to disambiguate.
>
> Thus for example
>
> di "a b c"
>
> is an instruction to display the literal string "a b c". -display-
> neither knows nor cares what that string means.
>
> In contrast,
>
> di a b c
>
> is an instruction to display the contents of a, followed by the contents
> of b, followed by the contents of c. -display- now needs to work at
> finding out what a, b and c are.
>
> Nick
>
> Rose a.k.a. [email protected] wrote:
>
>> Dear Martin,Dan and others,
>>
>> I am completely confused by the use of local marco.
>>
>> Take some examples,
>> r(files) after -fs-
>>
>> r(names) after -est dir-
>>
>> r(mean) after -su-
>>
>> //maybe the three above are not local marco, but I need to use it in my following procedure.
>>
>> r(levels) after -levelsof-
>> // it seems different when the type of variable following -levelsof- is different.
>> ........
>>
>> How to display and use them in my follwing procedure?
>> di `r(levels)'
>> di `"`r(levels)'"'
>> di `r(files)'
>> di `"`r(files)'"'
>> di `r(names)'
>> di r(mean)
>>
>> Something similar is,
>> local x="1 2"
>> local x "1 2"
>> local x 1 2
>> local x: r(mean)
>>
>> Concretely, when to add single quote and double quote? when to use colon?
>> especially,the difference among them.
>>
>
> *
> * For searches and help try:
> * http://www.stata.com/help.cgi?search
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
>
> *
> * For searches and help try:
> * http://www.stata.com/help.cgi?search
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
>
>
> ------------------------------------------------------------------------
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 8.5.392 / Virus Database: 270.13.45/2285 - Release Date: 08/06/09 05:57:00
>
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
