Getting substring

Getting substring

[Heime]

I have a variable named 'multistr' which may consist of multiple parts separated by spaces.
How can I get the string before the first space in elisp ?

(setq multistr "this that")
(message "%s" str) giving "this" 

Re: Getting substring

[Heime]

------- Original Message -------
On Wednesday, August 16th, 2023 at 9:26 PM, Heime <heimeborgia@protonmail.com> wrote:


> I have a variable named 'multistr' which may consist of multiple parts separated by spaces.
> How can I get the string before the first space in elisp ?
> 
> (setq multistr "this that")
> (message "%s" str) giving "this"

Have used 

  (setq str "bigoplus ⨁︁")
  (message "%s TEST: " (car (split-string str)))
  (setq str "bigoplus︁")
  (message "%s TEST: " (car (split-string str)))

Bet there is something very wrong with it.

Re: Getting substring

[Heime]

Sent with Proton Mail secure email.

------- Original Message -------
On Thursday, August 17th, 2023 at 1:18 AM, Heime <heimeborgia@protonmail.com> wrote:


> ------- Original Message -------
> On Wednesday, August 16th, 2023 at 9:26 PM, Heime heimeborgia@protonmail.com wrote:
> 
> 
> 
> > I have a variable named 'multistr' which may consist of multiple parts separated by spaces.
> > How can I get the string before the first space in elisp ?
> > 
> > (setq multistr "this that")
> > (message "%s" str) giving "this"
> 
> 
> Have used
> 
> (setq str "bigoplus ⨁︁")
> (message "%s TEST: " (car (split-string str)))
> (setq str "bigoplus︁")
> (message "%s TEST: " (car (split-string str)))
> 
> But there is something very wrong with it.

Why does the following not print the first word?

(message "%s TEST: " (car (split-string grafm)))

Re: Getting substring

[Pierre Rouleau]

> Why does the following not print the first word?
>
> (message "%s TEST: " (car (split-string grafm)))
>

Are you sure it does not print it?  It prints bigoplus  for me.
You can also look into the '*Message*' buffer to see what was printed by
the message function.


-- 
/Pierre

Re: Getting substring

[Pierre Rouleau]

I mean,
 Executing :
> (setq str "bigoplus ⨁︁")
> (message "%s TEST: " (car (split-string str)))

prints bigoplus.

but

(message "%s TEST: " (car (split-string grafm)))

will depend of what grafm holds.

On Wed, Aug 16, 2023 at 10:30 PM Pierre Rouleau <prouleau001@gmail.com>
wrote:

>
> Why does the following not print the first word?
>>
>> (message "%s TEST: " (car (split-string grafm)))
>>
>
> Are you sure it does not print it?  It prints bigoplus  for me.
> You can also look into the '*Message*' buffer to see what was printed by
> the message function.
>
>
> --
> /Pierre
>


-- 
/Pierre

Re: Getting substring

[Heime]

Sent with Proton Mail secure email.

------- Original Message -------
On Thursday, August 17th, 2023 at 2:33 PM, Pierre Rouleau <prouleau001@gmail.com> wrote:


> I mean,
> Executing :
> 
> > (setq str "bigoplus ⨁︁")
> > (message "%s TEST: " (car (split-string str)))
> 
> 
> prints bigoplus.
> 
> but
> 
> (message "%s TEST: " (car (split-string grafm)))
> 
> will depend of what grafm holds.
> 
> On Wed, Aug 16, 2023 at 10:30 PM Pierre Rouleau prouleau001@gmail.com
> 
> wrote:
> 
> > Why does the following not print the first word?
> > 
> > > (message "%s TEST: " (car (split-string grafm)))
> > 
> > Are you sure it does not print it? It prints bigoplus for me.
> > You can also look into the 'Message' buffer to see what was printed by
> > the message function. - Pierre

I now realise my mistake of putting "%s" before "TEST".  I was thus doing things
correctly after all.

The command (car (split-string grafm)) also works if there are no spaces in
'grafm', it still returns the string as a first element in the list result.

Re: Getting substring

[Heime]

Sent with Proton Mail secure email.

------- Original Message -------
On Thursday, August 17th, 2023 at 2:52 PM, Heime <heimeborgia@protonmail.com> wrote:


> 
> 
> 
> 
> 
> Sent with Proton Mail secure email.
> 
> 
> ------- Original Message -------
> On Thursday, August 17th, 2023 at 2:33 PM, Pierre Rouleau prouleau001@gmail.com wrote:
> 
> 
> 
> > I mean,
> > Executing :
> > 
> > > (setq str "bigoplus ⨁︁")
> > > (message "%s TEST: " (car (split-string str)))
> > 
> > prints bigoplus.
> > 
> > but
> > 
> > (message "%s TEST: " (car (split-string grafm)))
> > 
> > will depend of what grafm holds.
> > 
> > On Wed, Aug 16, 2023 at 10:30 PM Pierre Rouleau prouleau001@gmail.com
> > 
> > wrote:
> > 
> > > Why does the following not print the first word?
> > > 
> > > > (message "%s TEST: " (car (split-string grafm)))
> > > 
> > > Are you sure it does not print it? It prints bigoplus for me.
> > > You can also look into the 'Message' buffer to see what was printed by
> > > the message function. - Pierre
> 
> 
> I now realise my mistake of putting "%s" before "TEST". I was thus doing things
> correctly after all.
> 
> The command (car (split-string grafm)) also works if there are no spaces in
> 'grafm', it still returns the string as a first element in the list result.

Have started to wonder whether the following is wrong to do

(setq grafm "bigoplus ⨁︁")
(pcase (car (split-string grafm))
  "bigoplus" ("Detected bigoplus")) 

It is not a string.

Re: Getting substring

[Pierre Rouleau]

Heime,

I think you need to learn a little bit of Emacs Lisp, or Lisp.  Read a book
on Lisp to get you going.   Asking questions like you do won't help you
much.  You first need to understand LIsp and the way it deals with
functions, the concepts.

LISPcraft from Robert Wilensky is old (1984) but small and it covers the
basics which apply to Emacs Lisp.    It's a nice read and the book is
relatively small.


On Wed, Aug 16, 2023 at 11:01 PM Heime <heimeborgia@protonmail.com> wrote:

>
>
>
>
>
> Sent with Proton Mail secure email.
>
> ------- Original Message -------
> On Thursday, August 17th, 2023 at 2:52 PM, Heime <
> heimeborgia@protonmail.com> wrote:
>
>
> >
> >
> >
> >
> >
> > Sent with Proton Mail secure email.
> >
> >
> > ------- Original Message -------
> > On Thursday, August 17th, 2023 at 2:33 PM, Pierre Rouleau
> prouleau001@gmail.com wrote:
> >
> >
> >
> > > I mean,
> > > Executing :
> > >
> > > > (setq str "bigoplus ⨁︁")
> > > > (message "%s TEST: " (car (split-string str)))
> > >
> > > prints bigoplus.
> > >
> > > but
> > >
> > > (message "%s TEST: " (car (split-string grafm)))
> > >
> > > will depend of what grafm holds.
> > >
> > > On Wed, Aug 16, 2023 at 10:30 PM Pierre Rouleau prouleau001@gmail.com
> > >
> > > wrote:
> > >
> > > > Why does the following not print the first word?
> > > >
> > > > > (message "%s TEST: " (car (split-string grafm)))
> > > >
> > > > Are you sure it does not print it? It prints bigoplus for me.
> > > > You can also look into the 'Message' buffer to see what was printed
> by
> > > > the message function. - Pierre
> >
> >
> > I now realise my mistake of putting "%s" before "TEST". I was thus doing
> things
> > correctly after all.
> >
> > The command (car (split-string grafm)) also works if there are no spaces
> in
> > 'grafm', it still returns the string as a first element in the list
> result.
>
> Have started to wonder whether the following is wrong to do
>
> (setq grafm "bigoplus ⨁︁")
> (pcase (car (split-string grafm))
>   "bigoplus" ("Detected bigoplus"))
>
> It is not a string.
>
>

-- 
/Pierre

Re: Getting substring

[Heime]

Sent with Proton Mail secure email.

------- Original Message -------
On Thursday, August 17th, 2023 at 3:07 PM, Pierre Rouleau <prouleau001@gmail.com> wrote:


> Heime,
> 
> I think you need to learn a little bit of Emacs Lisp, or Lisp. Read a book
> on Lisp to get you going. Asking questions like you do won't help you
> much. You first need to understand LIsp and the way it deals with
> functions, the concepts.
> 
> LISPcraft from Robert Wilensky is old (1984) but small and it covers the
> basics which apply to Emacs Lisp. It's a nice read and the book is
> relatively small.
 
The error message (wrong-type-argument listp "bigoplus"), suggests that the code 
expects a list argument but is receiving a string instead.

Doing C-h f pcase says

(pcase EXP &rest CASES)

Evaluate EXP to get EXPVAL; try passing control to one of CASES.

Does not specify whether EXP is a string or whatever.

> On Wed, Aug 16, 2023 at 11:01 PM Heime heimeborgia@protonmail.com wrote:
> 
> > Sent with Proton Mail secure email.
> > 
> > ------- Original Message -------
> > On Thursday, August 17th, 2023 at 2:52 PM, Heime <
> > heimeborgia@protonmail.com> wrote:
> > 
> > > Sent with Proton Mail secure email.
> > > 
> > > ------- Original Message -------
> > > On Thursday, August 17th, 2023 at 2:33 PM, Pierre Rouleau
> > > prouleau001@gmail.com wrote:
> > > 
> > > > I mean,
> > > > Executing :
> > > > 
> > > > > (setq str "bigoplus ⨁︁")
> > > > > (message "%s TEST: " (car (split-string str)))
> > > > 
> > > > prints bigoplus.
> > > > 
> > > > but
> > > > 
> > > > (message "%s TEST: " (car (split-string grafm)))
> > > > 
> > > > will depend of what grafm holds.
> > > > 
> > > > On Wed, Aug 16, 2023 at 10:30 PM Pierre Rouleau prouleau001@gmail.com
> > > > 
> > > > wrote:
> > > > 
> > > > > Why does the following not print the first word?
> > > > > 
> > > > > > (message "%s TEST: " (car (split-string grafm)))
> > > > > 
> > > > > Are you sure it does not print it? It prints bigoplus for me.
> > > > > You can also look into the 'Message' buffer to see what was printed
> > > > > by
> > > > > the message function. - Pierre
> > > 
> > > I now realise my mistake of putting "%s" before "TEST". I was thus doing
> > > things
> > > correctly after all.
> > > 
> > > The command (car (split-string grafm)) also works if there are no spaces
> > > in
> > > 'grafm', it still returns the string as a first element in the list
> > > result.
> > 
> > Have started to wonder whether the following is wrong to do
> > 
> > (setq grafm "bigoplus ⨁︁")
> > (pcase (car (split-string grafm))
> > "bigoplus" ("Detected bigoplus"))
> > 
> > It is not a string.
> 
> 
> --
> /Pierre

Re: Getting substring

[Pierre Rouleau]

Heime,

reading the following might help
- https://www.gnu.org/software/emacs/manual/html_node/elisp/pcase-Macro.html
- https://www.emacswiki.org/emacs/PatternMatching

On Wed, Aug 16, 2023 at 11:16 PM Heime <heimeborgia@protonmail.com> wrote:

>
>
>
>
>
> Sent with Proton Mail secure email.
>
> ------- Original Message -------
> On Thursday, August 17th, 2023 at 3:07 PM, Pierre Rouleau <
> prouleau001@gmail.com> wrote:
>
>
> > Heime,
> >
> > I think you need to learn a little bit of Emacs Lisp, or Lisp. Read a
> book
> > on Lisp to get you going. Asking questions like you do won't help you
> > much. You first need to understand LIsp and the way it deals with
> > functions, the concepts.
> >
> > LISPcraft from Robert Wilensky is old (1984) but small and it covers the
> > basics which apply to Emacs Lisp. It's a nice read and the book is
> > relatively small.
>
> The error message (wrong-type-argument listp "bigoplus"), suggests that
> the code
> expects a list argument but is receiving a string instead.
>
> Doing C-h f pcase says
>
> (pcase EXP &rest CASES)
>
> Evaluate EXP to get EXPVAL; try passing control to one of CASES.
>
> Does not specify whether EXP is a string or whatever.
>
> > On Wed, Aug 16, 2023 at 11:01 PM Heime heimeborgia@protonmail.com wrote:
> >
> > > Sent with Proton Mail secure email.
> > >
> > > ------- Original Message -------
> > > On Thursday, August 17th, 2023 at 2:52 PM, Heime <
> > > heimeborgia@protonmail.com> wrote:
> > >
> > > > Sent with Proton Mail secure email.
> > > >
> > > > ------- Original Message -------
> > > > On Thursday, August 17th, 2023 at 2:33 PM, Pierre Rouleau
> > > > prouleau001@gmail.com wrote:
> > > >
> > > > > I mean,
> > > > > Executing :
> > > > >
> > > > > > (setq str "bigoplus ⨁︁")
> > > > > > (message "%s TEST: " (car (split-string str)))
> > > > >
> > > > > prints bigoplus.
> > > > >
> > > > > but
> > > > >
> > > > > (message "%s TEST: " (car (split-string grafm)))
> > > > >
> > > > > will depend of what grafm holds.
> > > > >
> > > > > On Wed, Aug 16, 2023 at 10:30 PM Pierre Rouleau
> prouleau001@gmail.com
> > > > >
> > > > > wrote:
> > > > >
> > > > > > Why does the following not print the first word?
> > > > > >
> > > > > > > (message "%s TEST: " (car (split-string grafm)))
> > > > > >
> > > > > > Are you sure it does not print it? It prints bigoplus for me.
> > > > > > You can also look into the 'Message' buffer to see what was
> printed
> > > > > > by
> > > > > > the message function. - Pierre
> > > >
> > > > I now realise my mistake of putting "%s" before "TEST". I was thus
> doing
> > > > things
> > > > correctly after all.
> > > >
> > > > The command (car (split-string grafm)) also works if there are no
> spaces
> > > > in
> > > > 'grafm', it still returns the string as a first element in the list
> > > > result.
> > >
> > > Have started to wonder whether the following is wrong to do
> > >
> > > (setq grafm "bigoplus ⨁︁")
> > > (pcase (car (split-string grafm))
> > > "bigoplus" ("Detected bigoplus"))
> > >
> > > It is not a string.
> >
> >
> > --
> > /Pierre
>


-- 
/Pierre

Re: Getting substring

[Pierre Rouleau]

> > Why does the following not print the first word?
> > >
> > > > (message "%s TEST: " (car (split-string grafm)))
> > >
> > > Are you sure it does not print it? It prints bigoplus for me.
> > > You can also look into the 'Message' buffer to see what was printed by
> > > the message function. - Pierre
>
> I now realise my mistake of putting "%s" before "TEST".  I was thus doing
> things
> correctly after all.
>
> The command (car (split-string grafm)) also works if there are no spaces in
> 'grafm', it still returns the string as a first element in the list result.
>
> Not sure I follow you...
- You do understand that message is just a string formatting function that
takes arguments to put in places identified by the '%s', right?
- And that format does something similar but just returns the formatted
string.
- therefore you can use ielm to test your code (use it!):

Here's a session:

ELISP> (setq str "bigoplus ⨁︁")
"bigoplus ⨁︁"
ELISP> (car (split-string str))
"bigoplus"
ELISP> (format " 123-- %s -- " (car (split-string str)))
" 123-- bigoplus -- "
ELISP> (format "%s TEST" (car (split-string str)))
"bigoplus TEST"
ELISP> (format "Survey says: %s " (car (split-string str)))
"Survey says: bigoplus "
ELISP>









-- 
/Pierre

Re: Getting substring

[Emanuel Berg]

Heime wrote:

> How can I get the string before the first space in elisp ?
>
> (setq multistr "this that")

(car (split-string "first string")) ; "first"

See the docstring for `split-string'.

-- 
underground experts united
https://dataswamp.org/~incal

Re: Getting substring

[Philip Kaludercic]

Emanuel Berg <incal@dataswamp.org> writes:

> Heime wrote:
>
>> How can I get the string before the first space in elisp ?
>>
>> (setq multistr "this that")
>
> (car (split-string "first string")) ; "first"
>
> See the docstring for `split-string'.

Another idea is to use regular expressions and their match data:

--8<---------------cut here---------------start------------->8---
(let ((str "this that"))
  (and (string-match "\\([^[:space:]]+\\)[[:space:]]?" str)
       (match-string 1 str)))
--8<---------------cut here---------------end--------------->8---