proc format;
   value typefmt 1='$groupx'
                 2='$groupy'
                 3='$groupz';
   value $groupx 'positive'='agree'
                 'negative'='disagree'
                 'neutral'='notsure ';
   value $groupy 'positive'='accept'
                 'negative'='reject'
                 'neutral'='possible';

   value $groupz 'positive'='pass    '
                 'negative'='fail'
                 'neutral'='retest';
run;

data answers;
   length word $ 8;
   input type response $;
   respfmt = put(type, typefmt.);
   word = putc(response, respfmt);
   datalines;
1 positive
1 negative
1 neutral
2 positive
2 negative
2 neutral
3 positive
3 negative
3 neutral
;

原本有一个数值型的变量，我copy成字符型的，想规定它的长度

put(source,format)

format具体填写什么，比如我生成的字符型变量长度是14

In this example, the first statement converts the values of CC, a numeric variable, into the four-character hexadecimal format, and the second writes the same value that the PUT function returns.
cchex=put(cc,hex4.);
put cc hex4.;