Question

我正在学习基础课作为高中课程。我在学校开始编程之前学过一些C ++。我正在撰写一个TELEPHONE DIRECTORY计划WRITES或READS FROM "Records.dat"文件。

当我运行程序并输入"Q"退出时，它运行正常。但是，如果我输入"E"输入APPEND MODE或"O"中的新记录以在OUTPUT模式或"V"中输入记录以查看记录，则该程序不会任何东西。它创建文件但不挂起，但它没有显示输出。这是代码：

10 CLS
20 Name$ = "0": Number$ = "0": Adrs$ = "0": Choice$ = "0": Mode$ = "0": Records = 0: Space = 0
30 PRINT "Telephone Directory Program."; "Press 'E' to Enter new records in Existing File"; "Press 'V' to View existing records"; "Press 'Q' to Exit"; "IF THERE ARE NO RECORDS PRESS O";
40 INPUT Mode$
50 IF Mode$ = "Q" THEN
    END
ELSEIF Mode$ = "E" THEN
    CLS
    OPEN "Records.dat" FOR APPEND AS #1
    ON ERROR GOTO 30
    PRINT "Enter Records when prompted.";
    WHILE Choice$ = "Y" OR Choice$ = "y"
        INPUT "Enter Name: ", Name$
        INPUT "Enter Phone Number: ", Number$
        INPUT "Enter Address: ", Adrs$
        WRITE #1, Name$, Number$, Adrs$
        INPUT "IF you want to enter new records, enter Y or y. Otherwise, press any other letter. ", Choice$
    WEND
    CLOSE #1
    GOTO 10
ELSEIF Mode$ = "O" THEN
    CLS
    OPEN "Records.dat" FOR OUTPUT AS #2
    PRINT "Enter Records when prompted.";
    WHILE Choice$ = "Y" OR Choice$ = "y"
        INPUT "Enter Name: ", Name$
        INPUT "Enter Phone Number: ", Number$
        INPUT "Enter Address: ", Adrs$
        WRITE #1, Name$, Number$, Adrs$
        INPUT "IF you want to enter new records, enter Y or y. Otherwise, press any other letter. ", Choice$
    WEND
    CLOSE #2
    GOTO 10
ELSEIF Mode$ = "V" THEN
    CLS
    OPEN "Records.dat" FOR INPUT AS #3
    PRINT SPC(24), "Directory Listing";
    WHILE NOT EOF(3)
        Records = Records + 1
    WEND
    IF Records = 0 THEN
        PRINT "NO RECORDS FOUND. ENTER O AT THE NEXT SCREEN";
        GOTO 10
    ELSE
        PRINT "Names", SPC(5), "Phone Numbers ", SPC(6), "Addresses";
        WHILE NOT EOF(3)
            INPUT #3, Name$, Number$, Adrs$
            PRINT Name$
            Space = (10 - (LEN(Name$)))
            PRINT SPC(Space)
            PRINT Number$
            Space = (20 - (LEN(Number$)))
            PRINT SPC(Space)
            PRINT Adrs$;
        WEND
        PRINT ;
        PRINT Records, " Records found";
        CLOSE #3
        GOTO 10
    END IF
END IF

Answer 1

WHILE Choice$ = "Y" OR Choice$ = "y"

您应该将Choice$初始化为"Y"而不是"0"来输入记录。否则，将跳过WHILE-WEND，因为在该循环之前无法为Choice$输入值。然后文件关闭，程序以GOTO 10重新启动。

查看记录时，您打开文件并想要记录记录。但是，WHILE NOT EOF(3)将永远运行;您不对该文件执行任何输入操作，因此它永远不会到达文件的末尾。如果没有记录，请不要忘记在CLOSE #3之前GOTO 10。

如果在创建数据库之前查看（V），也可能会出现“找不到文件”错误。您可以使用特殊的ON ERROR处理程序来解决此问题。以下内容应该有效：

    ON ERROR GOTO 900
    OPEN "Records.dat" FOR INPUT AS #3
    ON ERROR GOTO 0
    PRINT SPC(24), "Directory Listing";
    .
    .
    .
    END IF
END IF
END

900 PRINT "Records.dat not found; create it by entering records"
RESUME 10

请注意，我在最后END之后添加了END IF。由于您的程序现在是，当有人键入无效选项时，您不会执行任何操作。我猜这是你以后会做的事情。

无法用我的代码弄清楚错误（Qbasic 64bit）

1 个答案: