Pascal 程序抛出未知错误：EConvertError

我正在尝试创建一个程序，它接受用户的输入，并检查其有效日期是否为2000-2099年。当我对代码进行bug测试时，我连续两次输入enter作为输入，第一次输入enter时，没有抛出错误，但第二次控制台闪烁消息并崩溃。我在它崩溃时拍了一张截图，这是它显示的错误

An unhandled exception occured at $0040CDE1
EConvertError : "" is an invalid integer

我最好的猜测是，这个错误是由我的一个stroint由于EConvertError引起的，但我不清楚为什么它只在第二次运行时抛出，而不是第一次运行时抛出。我怀疑错误发生在第85、98、111或195行

当我最初编写这个程序时，a是Pascal的初学者，所以我为任何草率的代码提前道歉

下面是所有的代码，如果你想自己运行它

program DateVerifierAssignment;

uses crt, sysutils;

var
    userInputArray: array[0..7] of string;  
    len, i, day, month, year: integer;
    date, userInput, stringDay, stringMonth, stringYear: string;
    errorCatch: boolean;

//DECLARING FUNCTIONS & PROCEDURES
procedure TitleScreen();
    begin
    //prints a coloured wall of text to give information like name and instructions
    WriteLn(' o-------------------------o');
    Write(' | ');TextColor(White);Write('Date Validation Program');TextColor(Cyan);WriteLn(' |');
    WriteLn(' o-------------------------o');
    WriteLn();
    WriteLn(' o-------------------------o');
    Write(' |      ');TextColor(White);Write('Instructions');TextColor(Cyan);WriteLn('       |');
    WriteLn(' o-------------------------o');
    Write(' |   ');TextColor(White);Write('Enter a date and the');TextColor(Cyan);WriteLn('  |');
    Write(' | ');TextColor(White);Write('program will verify it');TextColor(Cyan);WriteLn('  |');
    Write(' |  ');TextColor(White);Write('and convert it to its');TextColor(Cyan);WriteLn('  |');
    Write(' |        ');TextColor(White);Write('long form');TextColor(Cyan);WriteLn('        |');
    WriteLn(' o-------------------------o');
    WriteLn();
    TextColor(White);
    Write('   press any key to begin');
    
    //waits for user input then clears the screen and returns the text color to white
    ReadKey();
    ClrScr;
    end;
         
       
function DateVerification(var userInput: string): boolean;
    var
        errorLimit : boolean;
        bounds: integer;
    begin
    errorLimit := True;
    //stores the length of the string as a variable
    len := Length(userInput);
    
    //checks to see if entry is 8 chracters long and displays an error message and returns user to input screen if it doesn't fit
    if (len <> 8) and (errorLimit = True) then
        begin
        ClrScr();
        TextColor(Red);
        WriteLn('input was not the right length (8 characters)');
        TextColor(White);
        Write('make sure date fits format ');
        TextColor(LightGreen);
        WriteLn('dd/mm/yy');
        TextColor(White);
        Readkey();
        ClrScr();
        errorLimit := false;
        Dateverification := false;
        end;
    
    //spits each character into its own spot in an array
    for i := 1 to len do
          userInputArray[i - 1] := userInput[i];
            
    //tests if every slot in the array where a slash should be is a slash
    for i := 0 to len-1 do
        begin
        if (userInputArray[2] <> '/') or (userInputArray[5] <> '/') and (errorLimit = true) then
            begin
            ClrScr();
            TextColor(Red);
            WriteLn('input did not have slashes in correct locations ');
            TextColor(LightGreen);
            WriteLn('dd/mm/yy');
            TextColor(White);
            Readkey();
            ClrScr();
            errorLimit := false;
            Dateverification := false;
            end;
        end;
        
    year := ((StrToInt(userInputArray[6]))*10) + StrToInt(userInputArray[7]);
    if (year < 1) or (year > 99) and (errorLimit = true) then
        begin
        ClrScr();
        TextColor(Red);
        WriteLn('year was not from 0 to 99');
        TextColor(White);
        Readkey();
        ClrScr();
        errorLimit := false;
        Dateverification := false;
        end;
        
    month := ((StrToInt(userInputArray[3]))*10) + StrToInt(userInputArray[4]);
        if (month < 1) or (month > 12) and (errorLimit = true) then
        begin
        ClrScr();
        TextColor(Red);
        WriteLn('month was not from 1 to 12');
        TextColor(White);
        Readkey();
        ClrScr();
        errorLimit := false;
        Dateverification := false;
        end;
    
    day :=  ((StrToInt(userInputArray[0]))*10) + StrToInt(userInputArray[1]);
    if (month = 4) or (month = 6) or (month = 9) or (month = 11) then
        bounds := 30;
    
    if (month = 2) then
        begin
        if (IsLeapYear(year) = true) then
            bounds := 29
        else
            bounds := 28;
        end
    else
        bounds := 31;    
    
    if (day < 1) or (day > bounds) and (errorLimit = true) then
            begin
            ClrScr();
            TextColor(Red);
            WriteLn('day was not from 1 to days in month');
            TextColor(White);
            Readkey();
            ClrScr();
            errorLimit := false;
            Dateverification := false;
            end;
    
    if (errorLimit = true) then  
        DateVerification := True;   
    end;    


function IsLeapYear(var year: integer): boolean;
//simple function to determine if a year is a leap year on the gregorian calender
    begin
        if (year mod 4) = 0 then
            if (year mod 100 <> 0) then
                if (year mod 400 = 0) then
                    IsLeapYear := true
                else
                    IsLeapYear := false
            else
                IsLeapyear := false
        else
            IsLeapyear := false    
    end;


procedure DateToAlpha(var userInput: string);
    begin
    
    end;
    

//MAIN PROGRAM
begin
    //preparing for while loop later in code and changes text colour to cyan
    errorCatch := true;
    TextColor(Cyan);
    
    //Displays a title screen and instruction about how to use(stored in a procedure to help with readability)
    TitleScreen();
     
    //begins a loop so that if an error is to occur the program can easily ask for a new date and try again
    while (errorCatch = true) do
        begin
        //sets error catch to 0 so that if there a no errors the program will not loop
        errorCatch := false;
        
        //displays information on how to input a date as well as an example with different colours for better readability
        Write('Enter a date in the format');TextColor(LightGreen); WriteLn(' dd/mm/yy');TextColor(White);
        Write('e.g. ');TextColor(LightGreen);WriteLn(' 09/07/20'#13#10);TextColor(White);
        
        //takes date user inputs and stores it
        ReadLn(userInput); 
        
        //calls the date verification function to see if the date is valid        
        //(refer to dateVerification at the top of the program for more info and comments)
        if (DateVerification(userInput) = false) then
            errorCatch := true;
            
        len := Length(userInput);
        for i := 1 to len do
          userInputArray[i - 1] := userInput[i];
        
        year := ((StrToInt(userInputArray[6]))*10) + StrToInt(userInputArray[7]);
        readKey();
        end;   
end.

---

通常情况下，我们不会提供完全编码的qs答案，这显然是课程作业

在这种情况下，我想我会破例，因为很明显，你是在犯错误 这是不必要的恶劣天气，而您编写代码的方式很可能会妨碍您 调试它并使其正常工作

下面的例子展示了一个非常简单的， 以dd/mm/yyyy格式提供的验证21世纪日期的干净方法。信息技术 显示处理和验证步骤的正确顺序；如果它检测到错误 在任何步骤中，它都会指出问题所在并停止。如果执行到最后， 提供的日期字符串必须有效

我故意省略了任何循环 或者美化代码，因为首先要做的最重要的事情是简洁明了 处理和验证步骤的编码。如果你想使用循环，很好，但是你使用的方式 e、 errorCatch，我敢打赌如果你在6个月后回到你的代码，你不会记得怎么做了 这应该是有效的。此任务不需要任何复杂的标志或循环-用户只需能够键入后跟[Enter]的八个字符，然后代码就会告诉您它是否有效

注意，我使用了标准的复制功能来分离 输入日期。顺便说一句，你的声明

userInputArray: array[0..7] of string;

这完全是错误的。如果您想要一个包含一定数量字符的数组，很好，但这会 只是不必要地使处理和处理用户键入的内容变得复杂。太远了 更简单，因此接受8个字符的单个字符串时更不容易出错 处理好这件事。但在任何情况下，为了允许字符串包含日期和月份数字之后的/字符，字符串的长度应为10，而不是8，以允许这些数字和4年数字

program DateVerification;

uses
  SysUtils;

var
  sUserInput,
  sDay,
  sMonth,
  sYear : String;
  iDay,
  iMonth,
  iYear,
  iDays: Integer;
  bIsLeapYear : Boolean;

function DaysInMonth(iMonth, iYear : Integer) : Integer;
begin
  Result := -1; //  you supply the code for this taking into account leap year for February
end;

begin
  writeln('Please enter a date between 01/01/2000 and 31/12/2099 in the format shown');
  readln(sUserInput);
  if Length(sUserInput) <> 10 then begin
    writeln('Input is wrong length.');
    Halt;
  end;
  if (sUserInput[3] <> '/') or (sUserInput[6] <> '/') then begin
    writeln('Input is incorrectly delimited.');
    Halt;
  end;

  sDay := Copy(sUserInput, 1, 2);
  sMonth := Copy(sUserInput, 4, 2);
  sYear := Copy(sUserInput, 7, 4);

  iYear := StrToInt(sYear);
  if (iYear < 2000) or (iYear > 2099) then begin
    writeln('Invalid year : ', sYear);
    Halt;
  end;

  bIsLeapYear := IsLeapYear(iYear); //  you supply the code for IsLeapYear

  iMonth := StrToInt(sMonth);
  if (iMonth < 1) or (iMonth > 12) then begin
    writeln('Invalid month : ', sMonth);
    Halt;
  end;

  iDay := StrToInt(sDay);

  if (iDay < 1) or (iDay > DaysInMonth(iMonth, iYear)) then begin
    //  You need to supply the DaysInMoth function, which of course
    //  needs to account for February in a leap year
    writeln('Invalid day of month: ', sMonth);
    Halt;
  end;

  writeln(sUserInput, ' is a valid date.');
  readln;

end.

---

你可能想和你的老师坐下来讨论课程。帮助您学习是他们的工作。在ReadLnuserInput之后，您应该做的第一件事是检查userInput的长度是否正确6？如果不是，则发出错误信号。错误长度的一个具体情况是用户刚刚按下[Enter]，在这种情况下，userInput将为空，在其任何部分调用StrToIn都会引发您提到的异常。顺便说一句，您有太多的变量-您不应该需要全部三个或errorLimit、errorCatch和DateVerification。简化…这篇文章中的代码太多了。请把它简化为一个注释，用“最小”这个词来说明你遇到的具体问题。@AndreasRejbrand[拍打额头的声音]哎呀！你当然是对的！结果是，我原来的代码没有考虑分隔符或四位数年份，然后我改变了主意，决定处理它们。我马上纠正它。非常感谢！