c++ - 从 wxString 转换为 double 时，小数位被解释为零

Question

我正在为 GUI 使用 wxWidgets，我需要将文本框中的字符串转换为 double ，这样我才能正确处理它们并将其用于计算，但程序似乎用 0 替换了所有小数位。这是当我将它从 wxString 转换为 double 时。我评论了错误发生的地方。我想你可能会看到整个代码。有点在下面。这是代码:

C++代码:

#include <wx/wx.h>
#include "determinantsFrame.h"
#include "starter.h"
#include <cmath>
#include <ctype.h>

using namespace std;

BEGIN_EVENT_TABLE(determinantsFrame, wxFrame)
    EVT_MENU(wxID_ABOUT, determinantsFrame::OnAbout)
    EVT_MENU(wxID_EXIT, determinantsFrame::OnQuit)
    EVT_CLOSE(determinantsFrame::OnClose)
    EVT_BUTTON(ID_Calculate, determinantsFrame::OnCalculateClick)
    EVT_BUTTON(ID_Reset, determinantsFrame::OnResetClick)
    EVT_BUTTON(ID_Fill, determinantsFrame::OnFillEmptyCellsWithZeroClick)
END_EVENT_TABLE()

int n;
wxTextCtrl *numbers[100][100];
const long determinantsFrame::ID_Calculate = wxNewId();
const long determinantsFrame::ID_Reset = wxNewId();
const long determinantsFrame::ID_Fill = wxNewId();

void determinantsFrame::OnClose(wxCloseEvent &event)
{
    exit(1);
}

void determinantsFrame::OnAbout(wxCommandEvent &event)
{
    wxString msg;
    msg.Printf(wxT("Toolkit used: %s"), wxVERSION_STRING);
    wxMessageBox(msg, wxT("About Determinants Calculator"));
}

void determinantsFrame::OnQuit(wxCommandEvent &event)
{
    Close();
}

determinantsFrame::~determinantsFrame()
{
    Destroy();
}

determinantsFrame::determinantsFrame() : wxFrame(NULL, wxID_ANY, wxT("Determinants Calculator"), wxDefaultPosition, wxDefaultSize, wxDEFAULT_FRAME_STYLE)
{
    fileMenu = new wxMenu;
    helpMenu = new wxMenu;
    menuBar = new wxMenuBar();

    helpMenu->Append(wxID_ABOUT, wxT("&About"), wxT("Show about dialog"));
    fileMenu->Append(wxID_EXIT, wxT("&Exit"), wxT("Quit this program"));

    menuBar->Append(fileMenu, wxT("&File"));
    menuBar->Append(helpMenu, wxT("&Help"));
    SetMenuBar(menuBar);

    while(true)
    {
        td = new wxTextEntryDialog(this, wxT("Enter the number of dimensions: "), wxGetTextFromUserPromptStr, wxT("2"));
        td->ShowModal();

        str = td->GetValue();
        n = wxAtoi(str);
        if (n != 0)
            break;
        else
            wxMessageBox(wxT("The dimension is n x n. You may have entered zero or an invalid character. Only an integer will be accepted such that n \nrepresents the dimension."));
    }

    mainBox = new wxBoxSizer(wxVERTICAL);
    MainPanel = new wxPanel(this, wxID_ANY);
    matrix = new wxStaticBoxSizer(wxVERTICAL, MainPanel, "Matrix: ");
    cells = new wxFlexGridSizer(0, n, 0, 0);
    subBox = new wxBoxSizer(wxVERTICAL);

    for (int i = 0; i < n; i++)
        for (int j = 0; j < n; j++)
        {
            numbers[i][j] = new wxTextCtrl(MainPanel, wxID_ANY, wxT(""), wxDefaultPosition, wxSize(50,20), 0, wxDefaultValidator, _T("ID_TextCtrl"));
            cells->Add(numbers[i][j], 0, wxALL | wxALIGN_CENTER_HORIZONTAL|wxALIGN_CENTER_VERTICAL, 5);
        }

    matrix->Add(cells, 1, wxALL|wxEXPAND|wxALIGN_CENTER_HORIZONTAL|wxALIGN_CENTER_VERTICAL, 2);
    subBox->Add(matrix, 1, wxALL|wxEXPAND|wxALIGN_CENTER_HORIZONTAL|wxALIGN_CENTER_VERTICAL, 5);

    wxBoxSizer *enb = new wxBoxSizer(wxHORIZONTAL);
    wxBoxSizer *rnb = new wxBoxSizer(wxHORIZONTAL);
    wxBoxSizer *bc = new wxBoxSizer(wxHORIZONTAL);

    Enter = new wxButton(MainPanel, ID_Calculate, _("Calculate"), wxDefaultPosition, wxDefaultSize, 0, wxDefaultValidator, _T("ID_Calculate"));
    Reset = new wxButton(MainPanel, ID_Reset, _("Reset"), wxDefaultPosition, wxDefaultSize, 0, wxDefaultValidator, _T("ID_Reset"));
    enb->Add(Enter, 1, wxALL |wxEXPAND|wxALIGN_CENTER_HORIZONTAL|wxALIGN_CENTER_VERTICAL, 5);
    rnb->Add(Reset, 1, wxALL |wxEXPAND|wxALIGN_CENTER_HORIZONTAL|wxALIGN_CENTER_VERTICAL, 5);
    bc->Add(enb, 0, wxALL | wxEXPAND);
    bc->Add(rnb, 0, wxALL | wxEXPAND);
    Enter->Bind(wxEVT_BUTTON, &determinantsFrame::OnCalculateClick, this);
    Reset->Bind(wxEVT_BUTTON, &determinantsFrame::OnResetClick, this);
    subBox->Add(bc, 0, wxALIGN_CENTER_HORIZONTAL|wxALIGN_CENTER_VERTICAL);
    FillEmptyCells = new wxButton(MainPanel, ID_Fill, _("Fill Empty Cells With Zero"), wxDefaultPosition, wxDefaultSize, 0, wxDefaultValidator, _T("ID_Fill"));
    subBox->Add(FillEmptyCells, 0, wxALL|wxALIGN_CENTER_HORIZONTAL|wxALIGN_CENTER_VERTICAL, 5);
    FillEmptyCells->Bind(wxEVT_BUTTON, &determinantsFrame::OnFillEmptyCellsWithZeroClick, this);
    MainPanel->SetSizer(subBox);
    mainBox->Add(MainPanel);
    mainBox->Fit(this);
    this->SetSizer(mainBox);
    CentreOnScreen();
}

void determinantsFrame::OnResetClick(wxCommandEvent &event)
{
    determinantsFrame *df;
    this->Show(false);
    df = new determinantsFrame();
    df->Show(true);
}

void determinantsFrame::OnFillEmptyCellsWithZeroClick(wxCommandEvent &event)
{
    for (int i = 0; i < n; i++)
        for (int j = 0; j < n; j++)
            if (numbers[i][j]->GetValue() == wxEmptyString)
                numbers[i][j]->SetValue(wxT("0"));
}

void determinantsFrame::OnCalculateClick(wxCommandEvent &event)
{
    double elem[MAX][MAX]; double det; string test; bool doIt = true;
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < n; j++)
        {
            test = (numbers[i][j]->GetValue()).mb_str();
            if (test == "")
            {
                doIt = false;
                break;
            }

            for (int k = 0; k < test.length(); k++)
                if (isalpha(test[k]) || test[k] == ' ')
                {
                    doIt = false;
                    break;
                }

            if (doIt == false)
                break;
        }
        if (doIt == false)
            break;
    }

    if (doIt)
    {
        for (int i = 0; i < n; i++)
            for (int j = 0; j < n; j++)
            {
                elem[i][j] = static_cast<double>(wxAtoi(numbers[i][j]->GetValue())); //here's where the problem occurs
                wxMessageBox(wxString::Format(wxT("The determinant is: %.2lf"), elem[i][j])); // here's what I use to test the values inside.
            }
        det = determinant(elem, n);
        wxMessageBox(wxString::Format(wxT("The determinant is: %.2lf"),det));
    }
    else
        wxMessageBox(wxT("You may have entered an invalid character. Please try again"));
}

double determinantsFrame::determinant(double matrix[MAX][MAX], int order)
{
    double det = 0; double temp[MAX][MAX]; int row, col;

    if (order == 1)
        return matrix[0][0];
    else if (order == 2)
        return ((matrix[0][0] * matrix[1][1]) - (matrix[0][1] * matrix[1][0]));
    else
    {
        for (int r = 0; r < order; r++)
        {
            col = 0; row = 0;
            for (int i = 1; i < order; i++)
            {
                for (int j = 0; j < order; j++)
                {
                    if (j == r)
                        continue;

                    temp[row][col] = matrix[i][j];
                    col++;

                    if (col == order - 1)
                        col = 0;
                }
                row++;
            }
            det = det + (matrix[0][r] * pow(-1, r) * determinant(temp, order - 1));
        }
        wxMessageBox(wxString::Format(wxT("The determinant is: %.2lf"),matrix[0][0]));
        return det;
    }
}

Answer 1

elem[i][j] = static_cast<double>(wxAtoi(numbers[i][j]->GetValue()));

替换为:

elem[i][j] = wxAtof(numbers[i][j]->GetValue());

函数 int wxAtoi (const wxString &str) 将 wsString 转换为 int。您需要 double wxAtof (const wxString &str) 将 wxString 转换为 double

wxWidgets 函数称为 CRT 函数包装器 的文档很少，因为每个这样的函数都包装了一些 CRT 函数。您可以在 C++ 引用中找到完整的 CRT 函数文档。例如，对于 wxAtoi，请参见 atoi 函数:http://www.cplusplus.com/reference/cstdlib/atoi/ ，对于 wxAtof 参见 atof 函数:http://www.cplusplus.com/reference/cstdlib/atof/