Edit Control in Microsoft Windows

An edit control in Microsoft Windows lets you type in a word or number. You probably also want an OK button for the user to press after typing in the word or number. How to Create a Single Line Edit Control.

Create the project

1. In Bloodshed Dev-Cpp, create a new project.
   File → New → Project…
   Press the Basic tab and select Windows Application.
   Name: Project1
   • C++ Project
   In the “Create a new project” window, select Desktop. Then press the yellow New Folder icon in the upper right (with rays coming out of its upper right corner). Name the new folder Project1.


2. File → New → Resource File
   Add new Resource to the current project?
   Yes
   This will create a new, empty resource file named Untitled1.rc. Put the following into it.

   //#include "resource.h"
   #include "windows.h"
   #include "winuser.h"
   #include "windef.h"
   
   //My window contains an edit control.
   #define IDD_MYWINDOW        1
   #define IDC_MYEDITCONTROL   2
   
   #ifndef IDC_STATIC
   #define IDC_STATIC (-1)
   #endif
   
   IDD_MYWINDOW DIALOGEX 0, 0, 169, 82
   STYLE DS_SETFONT | DS_MODALFRAME | WS_POPUP | WS_VISIBLE | WS_CAPTION | WS_SYSMENU
   CAPTION "This is my window."
   FONT 8, "MS Sans Serif", 0, 0, 0x0
   
   BEGIN
   	GROUPBOX        "Please input an integer.", IDC_STATIC, 10, 10, 150, 60
   	LTEXT           "The integer:", IDC_STATIC, 15, 20,70,8
   	EDITTEXT        IDC_MYEDITCONTROL, 15, 30, 44, 12, ES_AUTOHSCROLL
   	DEFPUSHBUTTON   "OK", IDOK, 15, 48, 50, 14
   END
   



3. At the start of the main.cpp file, before including windows.h, insert the following.

   #include <sstream>	//for classes istringstream and ostringstream
   using namespace std;
   



4. Define the same two macros at the start of main.cpp after including windows.h.

   #define IDD_MYWINDOW        1
   #define IDC_MYEDITCONTROL   2
   



5. Insert the following statement into the WinMain function in main.cpp immediately after the call to ShowWindow.

   	CreateDialog(
   		hThisInstance,
   		MAKEINTRESOURCE(IDD_MYWINDOW),
   		hwnd,
   		myDialogProc
   	);
   



6. The following function will be called when the user types a number and presses the OK button. Define the function immediately before the definition of the WinMain function.

   static INT_PTR CALLBACK myDialogProc(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
   {
   	switch (message) {
   	case WM_COMMAND:
   		switch(wParam) {
   		case IDOK: {
   			const size_t n = 12;	//number of characters
   			TCHAR lpszInteger[n];
   
   			//Get number of characters.
   			const WORD cchInteger = SendDlgItemMessage(hDlg,
                                   IDC_MYEDITCONTROL,
                                   EM_LINELENGTH,
                                   static_cast<WPARAM>(0),
                                   static_cast<LPARAM>(0)
   			);
   
   			if (cchInteger >= n) {
   				MessageBox(hDlg, "Too many characters.",
   					"Error", MB_OK);
   				EndDialog(hDlg, TRUE);
   				return FALSE;
   			}
   
   			if (cchInteger == 0) {
   				MessageBox(hDlg, "No characters entered.",
   					"Error", MB_OK);
   				EndDialog(hDlg, TRUE);
   				return FALSE;
   			}
   
   			//Put the number of characters into 1st word of buffer.
   			*reinterpret_cast<LPWORD>(lpszInteger) = cchInteger;
   
   			//Get the characters.
   			SendDlgItemMessage(
   				hDlg,
   				IDC_MYEDITCONTROL,
   				EM_GETLINE,
   				static_cast<WPARAM>(0),	//line 0
   				reinterpret_cast<LPARAM>(lpszInteger)
   			);
   
   			//Null-terminate the string.
   			lpszInteger[cchInteger] = '\0';
   
   			//Convert the string of characters to an integer.
   			const string s(lpszInteger);
   			istringstream ist(s);
   			int i;        //uninitialized variable
   			ist >> i;
   
   			++i;	//Perform arithmetic on the integer.
   
   			ostringstream ost;
   			ost << i;
   
   			MessageBox(hDlg, ost.str().c_str(), "Added 1:", MB_OK);
   			EndDialog(hDlg, TRUE);
   			return TRUE;
   		}
   
                   case IDCANCEL:
   			EndDialog(hDlg, TRUE);
   			return TRUE;
   
   		default:;
   		}
   
   	default:;
   	}
   
   	return FALSE;
   	UNREFERENCED_PARAMETER(lParam);
   }