大家帮忙看一下我这个编程对么 我要把time从时间型换成字符型 格式不匹配 替换不了
data a ;
input datetime datetime18. ;
format datetime datetime20.;
cards;
04jul1776:11:00
11dec1941:10:00
20apr1971:13:50
25dec2000:15:01
;
run;
data b;
set a;
time=timepart(datetime);
if time < '12:00't then time = 'morning';
else if time>'13:00't then time='afernoon';
run;