Thread: Keyboard input: Array of characters

I want to get some input from the user, put it in an array, and then display what they are typing on the screen. I'm using TextOut to do part of this, but am unable to figure out a way to update the output as the user fills the array.

When the user hits the enter key, I want to display what was entered, add one to it, and display the new number.

I would be grateful for any help anyone can give me.

Code:

//message handler (window procedure)
long CALLBACK WindowProc(HWND hwnd,UINT message,
                         WPARAM wParam,LPARAM lParam)
{
	HDC hdc;
	hdc = GetDC(hwnd);

	char * entstr = "Enter an Integer";
	TextOut(hdc, 280, 150, entstr, strlen(entstr));

	char * plus = "+ 1 =";
	
	char USERstr[11];
	USERstr[0] = 0;

	char strptr[11];
	strptr[0] = 0;

	int count = 280;

  switch(message)
  {
    case WM_ACTIVATEAPP: ActiveApp=wParam; break;
    case WM_CREATE: break; 
    case WM_KEYDOWN: //keyboard hit
		
     if(wParam >= 48 && wParam <= 57 && wParam != VK_RETURN) 
	{
				
	USERstr[0] = wParam;

	TextOut(hdc, count, 250 ,USERstr, 1);

	strcat(strptr, USERstr);

	count = count + 10;

	}

     if(wParam == VK_RETURN)
     {
	TextOut(hdc, 350, 400, strptr, strlen(strptr));
	TextOut(hdc, 390, 400, plus, strlen(plus));

     }


      if(wParam == VK_ESCAPE)DestroyWindow(hwnd);break;
	
    case WM_DESTROY: //end of game
      if(lpDirectDrawObject!=NULL){ //if DD object exists
        if(lpPrimary!=NULL) //if primary surface exists
          lpPrimary->Release(); //release primary surface
        lpDirectDrawObject->Release(); //release DD object
      }
      ShowCursor(TRUE); //show the mouse cursor
      PostQuitMessage(0); //and exit
      break;
    default: //default window procedure
      return DefWindowProc(hwnd,message,wParam,lParam);
  } //switch(message)
  return 0L;
} //WindowProc

Is there a reason you are trying to work with Windows API instead of console code? IMO it makes it much more difficult to learn C++ when trying to use the API.

Reading around the API doodah's you appear to be trying to use a char array as a string but you haven't NULL terminated it.

In this line:

USERstr[0] = wParam;

assuming the value in wParam can be interpretted as an ASCII char then you are assigning a single char to the first element of USERstr by doing this. But, since there is no terminating NULL char at then end of USERstr at this point, it is not a string, but just a char array with a char at element 0. Therefore, if TextOut() needs a string as the third parameter (which I suspect it does because I haven't seen an API function that takes just single char values yet, though my experience with Window API is far from extensive):

TextOut(hdc, count, 250 ,USERstr, 1);

then this call will fail. And I know this will fail, too:

strcat(strptr, USERstr);

for the same reason. To fix this you need to add a NULL char at the end of USERstr before you try to use it--like this:

USERstr[0] = wParam;
USERstr[1] = '\0'; //or whatever symbol you like to use for NULL. This assumes that wParam is a valid ASCII char value.

Also, I don't know whether you can concatenate onto the end of an empty string or not. If not, then you will need to use strcpy() the first time you want to "concatenate" USERstr onto strptr.

elad
I'm taking a class, and trying to learn how to use the API. Up until a few weeks ago, I had only worked with console code (with some success).

Thanks for that info.

joshdick
I'm unfamiliar with the string class.


I'm having difficulty stepping through my array. I don't know if I need an iteration inside the switch statement or not.

I'd like to step through the array and fill up as many buckets (up to ten) as I want with numbers (0-9). Convert that string to an integer, add one to the number and then print it out on the screen.