伪代码:
主程序
start:
result = getResult(mark)
if result > 0 then goto start
getResult
if mark < 0 then return -1
if mark > 100 then output("over 100") return 1
if 0 =mark then output("FAIL") return 2
if 50 =mark then output("PASS ") return 3
if 70 =mark then output("DISTINCTION ") return 4