**  主程序
set talk off
clear
use student2
for i=1 to 3 step 1
public a,b,flag
a="******"
b="******"
@ 4,50 say "學生操作系統"
@ 5,20 say "學生學號" get a
@ 6,20 say "學生密碼" get b
read
go top
flag=0
do while .not.eof()
if xh=a .and. mm=b
flag=1
endif
skip
enddo
if flag=1
clear
wait "歡迎登陸系統"
do 程序1.prg
**調用程序1 
do 程序1
clear
else
wait "輸入錯誤，請重新輸入"
endif
endfor
wait "3次錯誤，自動跳出
"
return