Replace only specific instance of a character

[Sas48]

Hi,
I am looking for a way to replace only the last ‘,’ with ‘and’ , if there are multiple instances of ‘,’

Tranwd replaces all instances of ‘,’ with ‘and’

Input:
Alpha beta , for a , for b , for c
Expected output:
Alpha beta , for a , for b and for c

Thank you.

[Shmuel]

You can use next code:

ix = index(varname,',',-1);   * -1 scans right to left;
if ix > 0 then   /* 0 means no comma found */
varname = substr(varname,1,ix-1) || ' and ' || substr(varname, ix+1);

You may nead assign new length to the varnamre as length('and") > lenght(',').

[Patrick · Accepted solution]

And just for fun here a RegEx option.

data sample;
  infile datalines truncover;
  input have_string $50.;

  /* define want_string with a length long enough to ensure there is never string truncation */
  if 0 then want_string=have_string||'and';

  want_string=prxchange('s/ *, *([^,]+)$/ and $1/oi',1,strip(have_string));

  datalines;
Alpha beta , for a , for b , for c
Alpha beta , for a , for b, for c
Alpha beta , for a , for b,for c
;

proc print data=sample;
run;