Clear
Accept "请输入字符串" to st
rt=""
i=len(st)
Do while ___________
rt=_______ +substr(st,i,1)
i=i-1
Enddo
?rt
横线填的啥

Clear
Accept "请输入字符串" to st
rt=""
i=len(st) && 取字符串长度
Do while ____i>0______ && 或者 i>=1
rt=___rt____ +substr(st,i,1) && 倒位累加字符，如输入 ABC,rt="C",rt="CB",rt="CBA"
i=i-1
Enddo
?rt

还可以这样写
Clear
Accept "请输入字符串" to st
rt=""
FOR i=LEN(st) TO 1 STEP -1
  rt=rt+substr(st,i,1) && 倒位累加字符，如输入 ABC,rt="C",rt="CB",rt="CBA"
ENDFOR
?rt


Clear
Accept "请输入字符串" to st
rt=""
FOR i=1 TO LEN(st)
 rt=substr(st,i,1) + rt && 倒位累加字符，如输入 ABC,rt="C",rt="CB",rt="CBA"
ENDFOR
?rt

Clear
Accept "请输入字符串" to st
rt=""
i=len(st)
Do while i>0
rt=rt +substr(st,i,1)
i=i-1
Enddo
?rt