[英]GetWindowText() in Win32 C++ is not working
以下代碼不起作用。我正在嘗試從編輯控件中獲取文本,但它不起作用。嘗試通過所有可能的代碼來查找msdn等上的文檔感到厭倦...
case WM_COMMAND:
switch(LOWORD(wParam)){
case 1:
::MessageBox(hwnd,"button clicked","message",MB_OK);
break;
case 2:
TCHAR t[20]; //
GetWindowText(text_box,t,19);// this is not working????????????????
::MessageBox(hwnd,t,t,MB_OK);
cout<<t;
break;
以下是完整的代碼:
#include <windows.h>
#include<iostream>
using namespace std;
const char g_szClassName[] = "myWindowClass";
// Step 4: the Window Procedure
LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
HWND text_field, button , text_box;
char text_saved[20];
switch(msg)
{ case WM_CREATE:
text_field = CreateWindow("STATIC",
"Hello World",
WS_VISIBLE | WS_CHILD | WS_BORDER,
20,20, 90,25,
hwnd,
NULL,NULL,NULL);
button = CreateWindow("BUTTON",
"push button",
WS_VISIBLE | WS_CHILD | WS_BORDER,
20,50, 100,20,
hwnd,
(HMENU)1,NULL,NULL
) ;
text_box = CreateWindow("EDIT",
" ",
WS_VISIBLE | WS_CHILD | WS_BORDER,
20,80, 200,25,
hwnd,
NULL,NULL,NULL
);
CreateWindow("BUTTON",
"Save",
WS_VISIBLE | WS_CHILD | WS_BORDER,
20,120, 100,20,
hwnd,
(HMENU)2,NULL,NULL
);
break;
case WM_COMMAND:
switch(LOWORD(wParam)){
case 1:
::MessageBox(hwnd,"button clicked","message",MB_OK);
break;
case 2:
TCHAR t[20];
GetWindowText(text_box,t,19);
::MessageBox(hwnd,t,t,MB_OK);
cout<<t;
break;
}
break;
case WM_CLOSE:
DestroyWindow(hwnd);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hwnd, msg, wParam, lParam);
}
return 0;
}
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPSTR lpCmdLine, int nCmdShow)
{
WNDCLASSEX wc;
HWND hwnd;
MSG Msg;
//Step 1: Registering the Window Class
wc.cbSize = sizeof(WNDCLASSEX);
wc.style = 0;
wc.lpfnWndProc = WndProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = hInstance;
wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
wc.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
wc.lpszMenuName = NULL;
wc.lpszClassName = g_szClassName;
wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
if(!RegisterClassEx(&wc))
{
MessageBox(NULL, "Window Registration Failed!", "Error!",
MB_ICONEXCLAMATION | MB_OK);
return 0;
}
// Step 2: Creating the Window
hwnd = CreateWindowEx(
WS_EX_CLIENTEDGE,
g_szClassName,
"The title of my window",
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, CW_USEDEFAULT, 500,500,
NULL, NULL, hInstance, NULL);
if(hwnd == NULL)
{
MessageBox(NULL, "Window Creation Failed!", "Error!",
MB_ICONEXCLAMATION | MB_OK);
return 0;
}
ShowWindow(hwnd, nCmdShow);
UpdateWindow(hwnd);
// Step 3: The Message Loop
while(GetMessage(&Msg, NULL, 0, 0) > 0)
{
TranslateMessage(&Msg);
DispatchMessage(&Msg);
}
return Msg.wParam;
}
您已將text_box
(和其他變量)定義為WndProc
函數的本地變量,這意味着每次調用該函數來處理消息時,它們的值都會丟失。 如果要將它們的值從一條消息保留到下一條消息,則需要將它們移出函數范圍(或使其變為static
)。
這是代碼的有效版本,用數字控件ID和GetDlgItem
用法替換了本地變量text_box
(不會保留從一個調用到下一個調用的信息),從ANSI更改為Unicode文本,並修復了其他一些問題東西,同時主要保持格式:
#undef UNICODE
#define UNICODE
#include <windows.h>
#include<iostream>
#include <string>
using namespace std;
namespace g {
const auto class_name = L"myWindowClass";
const auto push_button_id = 1;
const auto save_button_id = 2;
const auto edit_field_id = 3;
const auto h_instance = ::GetModuleHandle( nullptr );
} // namespace g
// Step 4: the Window Procedure
void create_controls( const HWND hwnd )
{
CreateWindow( L"STATIC",
L"Hello World",
WS_VISIBLE | WS_CHILD | WS_BORDER,
20,20, 90,25,
hwnd,
nullptr, g::h_instance, nullptr );
CreateWindow( L"BUTTON",
L"push button",
WS_VISIBLE | WS_CHILD | WS_BORDER,
20,50, 100,20,
hwnd,
(HMENU) g::push_button_id, g::h_instance, nullptr
) ;
CreateWindow( L"EDIT",
L"",
WS_VISIBLE | WS_CHILD | WS_BORDER,
20,80, 200,25,
hwnd,
(HMENU) g::edit_field_id, g::h_instance, nullptr
);
CreateWindow( L"BUTTON",
L"Save",
WS_VISIBLE | WS_CHILD | WS_BORDER,
20,120, 100,20,
hwnd,
(HMENU) g::save_button_id, g::h_instance, nullptr
);
}
LRESULT CALLBACK WndProc( HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam )
{
switch(msg)
{
case WM_CREATE:
create_controls( hwnd );
break;
case WM_COMMAND:
switch(LOWORD(wParam)) {
case 1:
::MessageBox( hwnd, L"button clicked", L"message", MB_SETFOREGROUND );
break;
case 2:
const HWND text_box = GetDlgItem( hwnd, g::edit_field_id );
const int n = GetWindowTextLength( text_box );
wstring text( n + 1, L'#' );
if( n > 0 )
{
GetWindowText( text_box, &text[0], text.length() );
}
text.resize( n );
::MessageBox(hwnd, text.c_str(), L"The text:", MB_SETFOREGROUND );
break;
}
break;
case WM_CLOSE:
DestroyWindow(hwnd);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hwnd, msg, wParam, lParam);
}
return 0;
}
int main()
{
//Step 1: Registering the Window Class
WNDCLASSEX wc = { sizeof( WNDCLASSEX ) };
wc.style = 0;
wc.lpfnWndProc = WndProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = g::h_instance;
wc.hIcon = LoadIcon(nullptr, IDI_APPLICATION);
wc.hCursor = LoadCursor(nullptr, IDC_ARROW);
wc.hbrBackground = reinterpret_cast<HBRUSH>(COLOR_WINDOW+1);
wc.lpszMenuName = nullptr;
wc.lpszClassName = g::class_name;
wc.hIconSm = LoadIcon(nullptr, IDI_APPLICATION);
if(!RegisterClassEx(&wc))
{
MessageBox(nullptr, L"Window Registration Failed!", L"Error!",
MB_ICONEXCLAMATION | MB_SETFOREGROUND );
return E_FAIL;
}
// Step 2: Creating the Window
const HWND hwnd = CreateWindowEx(
WS_EX_CLIENTEDGE,
g::class_name,
L"The title of my window",
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, CW_USEDEFAULT, 500,500,
nullptr, nullptr, g::h_instance, nullptr);
if(hwnd == nullptr)
{
MessageBox(nullptr, L"Window Creation Failed!", L"Error!",
MB_ICONEXCLAMATION | MB_SETFOREGROUND);
return E_FAIL;
}
ShowWindow(hwnd, SW_SHOWDEFAULT); // Note: any other value is replaced.
UpdateWindow(hwnd); // Not strictly necessary.
// Step 3: The Message Loop
MSG Msg;
int get_message_result;
while( (get_message_result = GetMessage(&Msg, nullptr, 0, 0)) > 0 )
{
TranslateMessage(&Msg);
DispatchMessage(&Msg);
}
return (get_message_result < 0? E_FAIL : Msg.wParam);
}
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.