C++ Win32 - 将文本附加到编辑控件
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Win32 - Appending text to an Edit Control
提问by ShrimpCrackers
Trying to append text to an edit control inside a dialog box. I can't get _tcscat_s to append correctly. It crashes and says something about the buffer being too small or something about a null terminated string.
尝试将文本附加到对话框内的编辑控件。我无法让 _tcscat_s 正确附加。它崩溃并说明缓冲区太小或空终止字符串。
int WINAPI WinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow )
{
return DialogBox( hInstance, MAKEINTRESOURCE( IDD_MAIN ), NULL, DlgProc );
}
BOOL CALLBACK DlgProc( HWND hwnd, UINT Message, WPARAM wParam, LPARAM lParam )
{
switch( Message )
{
case WM_INITDIALOG:
OpenAndReadFile( hwnd );
return TRUE;
case WM_COMMAND:
switch( LOWORD( wParam ) )
{
case IDSTART:
EndDialog( hwnd, IDSTART );
break;
case IDQUIT:
EndDialog( hwnd, IDQUIT );
break;
}
break;
case WM_CLOSE:
EndDialog( hwnd, 0 );
break;
default:
return FALSE;
}
return TRUE;
}
BOOL OpenAndReadFile( const HWND &hwnd )
{
// Open the file
HANDLE hFile;
hFile = CreateFile( TEXT( "sites.txt" ), // file to open
GENERIC_READ, // open for reading
FILE_SHARE_READ, // share for reading
NULL, // default security
OPEN_EXISTING, // existing file only
FILE_ATTRIBUTE_NORMAL, // normal file
NULL ); // no attr. template
if ( hFile == INVALID_HANDLE_VALUE )
{
SetDlgItemText( hwnd, IDC_OUTPUT, TEXT( "Error: File could not be opened\r\n" ) );
return FALSE;
}
else
SetDlgItemText( hwnd, IDC_OUTPUT, TEXT( "sites.txt opened\r\n" ) );
AppendText( hwnd, TEXT("TEXT") );
// Read data from file
const DWORD BUFFERSIZE = GetFileSize( hFile, NULL );
char *ReadBuffer = new char [BUFFERSIZE]();
DWORD dwBytesRead = 0;
// read one character less than the buffer size to save room for the
// terminate NULL character.
//if ( FALSE == ReadFile( hFile, ReadBuffer, BUFFERSIZE - 1, &dwBytesRead, NULL ) )
{
}
return TRUE;
}
void AppendText( const HWND &hwnd, TCHAR *newText )
{
// get size to determine buffer size
int outLength = GetWindowTextLength( GetDlgItem( hwnd, IDC_OUTPUT ) );
// create buffer to hold current text in edit control
TCHAR * buf = ( TCHAR * ) GlobalAlloc( GPTR, outLength + 1 );
// get existing text from edit control and put into buffer
GetDlgItemText( hwnd, IDC_OUTPUT, buf, outLength + 1 );
// append the newText to the buffer
_tcscat_s( buf, outLength + 1, newText );
// Set the text in the dialog
SetDlgItemText( hwnd, IDC_OUTPUT, buf );
}
回答by Remy Lebeau
GetWindowTextLength()returns the number of TCHARelements in the text, but GlobalAlloc()expects a byte count instead. If you are compiling for Unicode, TCHARis 2 bytes, not 1 byte, but you are not taking that into account. You are also not allocating the buffer large enough to hold both the existing text and the new text being appended. You are also leaking the memory that you allocate.
GetWindowTextLength()返回TCHAR文本中的元素数，但GlobalAlloc()需要字节数。如果您正在为 Unicode 编译，TCHAR则是 2 个字节，而不是 1 个字节，但您没有考虑到这一点。您也没有分配足够大的缓冲区来容纳现有文本和附加的新文本。您也正在泄漏您分配的内存。
Try this:
尝试这个：
void AppendText( const HWND &hwnd, TCHAR *newText )
{
// get edit control from dialog
HWND hwndOutput = GetDlgItem( hwnd, IDC_OUTPUT );
// get new length to determine buffer size
int outLength = GetWindowTextLength( hwndOutput ) + lstrlen(newText) + 1;
// create buffer to hold current and new text
TCHAR * buf = ( TCHAR * ) GlobalAlloc( GPTR, outLength * sizeof(TCHAR) );
if (!buf) return;
// get existing text from edit control and put into buffer
GetWindowText( hwndOutput, buf, outLength );
// append the newText to the buffer
_tcscat_s( buf, outLength, newText );
// Set the text in the edit control
SetWindowText( hwndOutput, buf );
// free the buffer
GlobalFree( buf );
}
Alternatively:
或者：
#include <vector>
void AppendText( const HWND &hwnd, TCHAR *newText )
{
// get edit control from dialog
HWND hwndOutput = GetDlgItem( hwnd, IDC_OUTPUT );
// get new length to determine buffer size
int outLength = GetWindowTextLength( hwndOutput ) + lstrlen(newText) + 1;
// create buffer to hold current and new text
std::vector<TCHAR> buf( outLength );
TCHAR *pbuf = &buf[0];
// get existing text from edit control and put into buffer
GetWindowText( hwndOutput, pbuf, outLength );
// append the newText to the buffer
_tcscat_s( pbuf, outLength, newText );
// Set the text in the edit control
SetWindowText( hwndOutput, pbuf );
}
With that said, getting the window's current text into memory, appending to it, and then replacing the window's text is a very inefficient way to append text to an edit control. Use the EM_REPLACESELmessage instead:
话虽如此，将窗口的当前文本放入内存，附加到它，然后替换窗口的文本是将文本附加到编辑控件的一种非常低效的方式。改用EM_REPLACESEL消息：
void AppendText( const HWND &hwnd, TCHAR *newText )
{
// get edit control from dialog
HWND hwndOutput = GetDlgItem( hwnd, IDC_OUTPUT );
// get the current selection
DWORD StartPos, EndPos;
SendMessage( hwndOutput, EM_GETSEL, reinterpret_cast<WPARAM>(&StartPos), reinterpret_cast<WPARAM>(&EndPos) );
// move the caret to the end of the text
int outLength = GetWindowTextLength( hwndOutput );
SendMessage( hwndOutput, EM_SETSEL, outLength, outLength );
// insert the text at the new caret position
SendMessage( hwndOutput, EM_REPLACESEL, TRUE, reinterpret_cast<LPARAM>(newText) );
// restore the previous selection
SendMessage( hwndOutput, EM_SETSEL, StartPos, EndPos );
}
回答by fider
http://support.microsoft.com/kb/109550
http://support.microsoft.com/kb/109550
Is your answer:
你的答案是：
string buffer = "append this!"
HWND hEdit = GetDlgItem (hDlg, ID_EDIT);
int index = GetWindowTextLength (hEdit);
SetFocus (hEdit); // set focus
SendMessageA(hEdit, EM_SETSEL, (WPARAM)index, (LPARAM)index); // set selection - end of text
SendMessageA(hEdit, EM_REPLACESEL, 0, (LPARAM)buffer.c_str()); // append!
