TStringGrid 输入验证仅允许 C++ Builder XE8 上的数字、小数和逗号

TStringGrid Input Validation to permit only numbers, decimals, and commas on C++ Builder XE8

这个问题是另一个问题的延伸:

我有一个可编辑的TStringGrid。我只希望用户为网格中的每个单元格键入数字和最多一位小数点或逗号。

从上面的内容 link,我了解了如何只允许某些键,但不知道如何跟踪给定单元格中某个键值已存在的次数。

从上面link,我有这个:

void __fastcall TSetDataForm::ProbabilityGridKeyPress(TObject *Sender, System::WideChar &Key)
{
    if( Key == VK_BACK )
        return;

    if( (Key < L'0') || (Key > L'9') )
    {
        ShowMessage("Please enter numerals only");
        Key = 0;
    }
}

如何允许 '.'',' 但只有一次?

我的问题是因为我不知道如何阅读用户正在写入的单元格中的文本。

这是我的解决方案,供任何感兴趣的人使用:

void __fastcall TSetDataForm::ProbabilityGridKeyPress(TObject *Sender, System::WideChar &Key)
{
    if( Key == VK_BACK )
        return;

    if( !((Key >= L'0') && (Key <= L'9') || (Key == L'.')))
    {
        ShowMessage("Please enter numerals only");
        Key = 0;
    }
    else if ((Key == L'.') &&
        (Pos(Key, ProbabilityGrid->Cells[ProbabilityGrid->Col][ProbabilityGrid->Row]) > 0))
    {
        ShowMessage("Two dots!");
        Key = 0;
    }
}

我建议使用 TryStrToFloat() 来验证输入,这样用户是否输入了有效的十进制字符串就毫无疑问了。您只需要处理以下额外情况:

  • 用户正在编辑字段末尾以外的地方键入字符,选择或未选择文本。

  • 用户正在copy/pasting文本编辑器中。

例如:

class TStringGridAccess : public TStringGrid
{
public:
    __property InplaceEditor;
};

void __fastcall TSetDataForm::ProbabilityGridKeyPress(TObject *Sender, System::WideChar &Key)
{
    switch (Key)
    {
        case 3: // Ctrl-C
        case 8: // Backspace
            return;

        case 22: // Ctrl-V
        {
            Key = 0;

            TInplaceEdit *Editor = ((TStringGridAccess*)ProbabilityGrid)->InplaceEditor;

            String SaveCellText = ProbabilityGrid->Cells[ProbabilityGrid->Col][ProbabilityGrid->Row];

            String SaveEditText = Editor->Text;
            int SaveSelStart = Editor->SelStart;
            int SaveSelLen = Editor->SelLength;

            Editor->Perform(WM_PASTE, 0, 0);

            TFormatSettings fmt = TFormatSettings::Create();
            fmt.DecimalSeparator = _D('.');

            double value;
            if (TryStrToFloat(Editor->Text, value, fmt))
                return;

            ProbabilityGrid->Cells[ProbabilityGrid->Col][ProbabilityGrid->Row] = SaveCellText;

            Editor->Text = SaveEditText;
            Editor->SelStart = SaveSelStart;
            Editor->SelLength = SaveSelLen;

            break;
        }

        case _D('0'):
        case _D('1'):
        case _D('2'):
        case _D('3'):
        case _D('4'):
        case _D('5'):
        case _D('6'):
        case _D('7'):
        case _D('8'):
        case _D('9'):
        case _D('.'):
        {
            TInplaceEdit *Editor = ((TStringGridAccess*)ProbabilityGrid)->InplaceEditor;

            String str = Editor->Text;
            int idx = Editor->SelStart;
            int len = Editor->SelLength;

            String str2 = str.SubString(1, idx) + Key + str.SubString(1+idx+len, MaxInt);

            TFormatSettings fmt = TFormatSettings::Create();
            fmt.DecimalSeparator = _D('.');

            double value;
            if (TryStrToFloat(str2, value, fmt))
                return;

            break;
        }
    }

    ShowMessage(_D("Please enter decimals only"));
    Key = 0;
}