How %cmpres function works

[thanikondharish]

%let a= abcd efgh ijkl ;

%put %cmpres(&a) ;

Above a macro variable not compressing.
The %cmpres how works
I need value like abcdefghijkl

[Shmuel]

Either run code preceding with options mprint symbolgen; and post the log

Or change code to %compress(&a);

[jvdl]

The %CMPRES function removes multiple spaces, as well as leading and trailing spaces. However, it will preserve single spaces in between.

Try the following:

%let a= abcd efgh ijkl ;
%put %sysfunc(compress(&a));

[Tom]

Note that system macro is ancient.  You can use %SYSFUNC() now and avoid those macro loops.  To get similar results to %CMPRES() use %SYSFUNC(COMPBL()).  To remove all spaces use %SYSFUNC(COMPRESS()).

152   %let a= abcd    efgh ijkl ;
153
154   %put a        |&a| ;
a        |abcd    efgh ijkl|
155   %put cmpress  |%cmpres(&a)| ;
cmpress  |abcd efgh ijkl|
156   %put compbl   |%sysfunc(compbl(&a))| ;
compbl   |abcd efgh ijkl|
157   %put compress |%sysfunc(compress(&a))| ;
compress |abcdefghijkl|

If you want to see how CMPRES works you can read the code.

%macro cmpres(text);
%*********************************************************************;
%*                                                                   *;
%*  MACRO: CMPRES                                                    *;
%*                                                                   *;
%*  USAGE: 1) %cmpres(argument)                                      *;
%*                                                                   *;
%*  DESCRIPTION:                                                     *;
%*    This macro returns the argument passed to it in an unquoted    *;
%*    form with multiple blanks compressed to single blanks and also *;
%*    with leading and trailing blanks removed.                      *;
%*                                                                   *;
%*    Eg. %let macvar=%cmpres(&argtext)                              *;
%*                                                                   *;
%*  NOTES:                                                           *;
%*    The %LEFT and %TRIM macros in the autocall library are used    *;
%*    in this macro.                                                 *;
%*                                                                   *;
%*********************************************************************;
%local i;
%let i=%index(&text,%str(  ));
%do %while(&i ne 0);
  %let text=%qsubstr(&text,1,&i)%qleft(%qsubstr(&text,&i+1));
  %let i=%index(&text,%str(  ));
%end;
%left(%qtrim(&text))
%mend;

Of course you will also need the code for the %LEFT() and %QTRIM() macros.

%macro left(text);                                                      
%*********************************************************************; 
%*                                                                   *; 
%*  MACRO: LEFT                                                      *; 
%*                                                                   *; 
%*  USAGE: 1) %left(argument)                                        *; 
%*                                                                   *; 
%*  DESCRIPTION:                                                     *; 
%*    This macro returns the argument passed to it without any       *; 
%*    leading blanks in an unquoted form. The syntax for its use     *; 
%*    is similar to that of native macro functions.                  *; 
%*                                                                   *; 
%*    Eg. %let macvar=%left(&argtext)                                *; 
%*                                                                   *; 
%*  NOTES:                                                           *; 
%*    The %VERIFY macro is used to determine the first non-blank     *; 
%*    character position.                                            *; 
%*                                                                   *; 
%*********************************************************************; 
%local i;                                                               
%if %length(&text)=0 %then %let text=%str( );                           
%let i=%verify(&text,%str( ));                                          
%if &i %then %substr(&text,&i);                                         
%mend;    

%macro qtrim(value);
%*********************************************************************;
%*                                                                   *;
%*  MACRO: QTRIM                                                     *;
%*                                                                   *;
%*  USAGE: 1) %qtrim(argument)                                       *;
%*                                                                   *;
%*  DESCRIPTION:                                                     *;
%*    This macro returns the argument passed to it without any       *;
%*    trailing blanks in a quoted form. The syntax for its use       *;
%*    is similar to that of native macro functions.                  *;
%*                                                                   *;
%*    Eg. %let macvar=%qtrim(&argtext)                               *;
%*                                                                   *;
%*  NOTES:                                                           *;
%*    None.                                                          *;
%*                                                                   *;
%*********************************************************************;
  %local i;
  %do i=%length(&value) %to 1 %by -1;
    %if %qsubstr(&value,&i,1) ne %str( ) %then %goto trimmed;
  %end;
  %trimmed: %if &i>0 %then %qsubstr(&value,1,&i);
%mend;

Which to understand you will have to read the VERIFY macro.

%macro verify(text,target);
%*********************************************************************;
%*                                                                   *;
%*  MACRO: VERIFY                                                    *;
%*                                                                   *;
%*  USAGE: 1) %verify(argument,target)                               *;
%*                                                                   *;
%*  DESCRIPTION:                                                     *;
%*    This macro returns the position of the first character in the  *;
%*    argument that is not in the target value. If every character   *;
%*    that is in the argument is also in the target value then this  *;
%*    fuction returns a value of 0. The syntax for its use is        *;
%*    is similar to that of native macro functions.                  *;
%*                                                                   *;
%*    Eg. %let i=%verify(&argtext,&targtext)                         *;
%*                                                                   *;
%*  SUPPORT: sassmo                                                  *;
%*  NOTES:                                                           *;
%*    Both values to this function must have non-zero lengths or an  *;
%*    error message will be produced.                                *;
%*                                                                   *;
%*********************************************************************;
%local i;
%if %length(&text)=0 OR %length(&target)=0 %then %do;
  %put ERROR: ARGUMENT TO VERIFY FUNCTION MISSING.;

  %goto errout;
%end;
%do i=1 %to %length(&text);
  %if NOT %index(&target,%qsubstr(&text,&i,1)) %then %goto verfnd;
%end;
%verfnd: %if &i>%length(&text) %then 0;
           %else &i;
%errout:
%mend;