P1：Code

/*********************************************************************
***  Program: ms_char_set_len.sas
***  Programmer: Kai Cao
***  Date: 10Sep2021
***  Study: all study
***  Version: 1.0 
***  Input dataset: dataset len 
***  Output : __len_list
***  Description: Use SAS Macros to set uniform lengths for data set variables 
 

        dataset:   required. Data set whose length needs to be modified.
                             such as td1 ;
        len    :   optional. Set the length of string variables uniformly.
                             the default is 12000;
*********************************************************************
***  MODIFICATIONS:
***  Programmer:
***  Date:
***  Reason:
***
*********************************************************************/

/*%let len=12000;*/
/*%let dataset=ae2_;*/


%macro ms_char_set_len(dataset=%str(td1),
                        len=%str(12000));
    /*create column-len mapping*/
    data null;
        set &dataset.;
        array char_vars{*} $&len. _character_;
        if _N_=1 then do ;
            do i= 1 to dim(char_vars);
                __column=vname(char_vars{i});
                __len=&len.;output; 
            end;
        end;
        keep __:;
    run;

    /*convert to macros vars*/
    proc sql noprint;
        select "length " ||strip(__column)||" $&len. ;" into : __len_list separated by " "
        from null
    ;
    quit;

    /*delect the work.null dataset*/
    proc sql noprint;
        drop table work.null;
    quit;
    
%mend;

/*%put &__len_list.;*/


*---------------------------------------------------*
* Example                                           *
*---------------------------------------------------*;
/*%include "/usrfiles/bgcrh/support/utilities/init/init_global.sas";*/
/*libname uatdata_ "&import/irt_data" ;*/
/**/
/*proc copy in=uatdata_ out=work;*/
/*    select td td1;*/
/*run;*/
/**/
/*options mlogic mprint nosymbolgen;*/
/*%ms_char_set_len(dataset=%str(td1)); *%ms_char_set_len(dataset=%str(td1),len=%str(100));*/
/*data test2;*/
/*   &__len_list.*/
/*  set td1;*/
/*run;*/

P2：Usage:

导入td1数据集，对字符变量设置恒定长度；

%include "/usrfiles/bgcrh/build/training_project_1/practice_wh/cp/dev/pgm/vendor_recon/kai_cao/ms_char_set_len.sas";
libname uatdata_ "&import/irt_data" ;

proc copy in=uatdata_ out=work;
    select td td1;
run;

options mlogic mprint nosymbolgen;
%ms_char_set_len(dataset=%str(td1)); *%ms_char_set_len(dataset=%str(td1),len=%str(100));
data test2;
     &__len_list.
    set td1;
run;