Thanks Malcolm

#include <windows.h>
#include<cmath>
HWND text_box1; // declare before the switch otherwise you have cross initialisation
HWND text_box2; // declare before the switch otherwise you have cross initialisation
HWND text_box3; // declare before the switch otherwise you have cross initialisation
HWND text_box4; // declare before the switch otherwise you have cross initialisation

HWND button1; // declare before the switch otherwise you have cross initialisation
HWND button2; // declare before the switch otherwise you have cross initialisation
HWND button3; // declare before the switch otherwise you have cross initialisation
HWND button4; // declare before the switch otherwise you have cross initialisation


void  convert_to_bin(int myint,char buff[])
{   int index=1;
    for (int j=0;j<=31;j++)
	{
		if ( ( myint & index ) !=0  ) buff[31-j]='1';
		else buff[31-j]='0';
        index=index<<1;
    }//for
}// convert operation

int back_to_int(char buff[])
{
    int digit,num=0;
    for (int j=1;j<=31;j++)
    {
	if (buff[j]=='1') digit=1;
	else digit=0;
    num=2*num+digit;
    }
    if (buff[0]=='1'){ num=num+(int)pow(2,31)+1; }   // negative numbers
    return num;
}
void floatToBinary(float my_float, char buff[])
{

    int *ptrToTheFloat = (int*) &my_float;
    int indexX = 1;
    for(int i = 0; i < 31; i++)
    {
        buff[i] = ((*ptrToTheFloat) & indexX)/indexX + '0';
        indexX *= 2;
    }



}
/*
void binaryToFloat(float *theNumber, char array[], const int *sizeOfTheArray)
{
    cout <<"enter a binary" << endl;
    cin >> array;
    int *ptrToTheFloat = (int*) &(*theNumber);
    *theNumber = 0;
    for(int i = 0; i < *sizeOfTheArray; i++)
    {
        *ptrToTheFloat = ((*ptrToTheFloat)*2) + array[i] -'0';
    }

    cout << *theNumber << endl;

}



*/



/* This is where all the input to the window goes to */
LRESULT CALLBACK WndProc(HWND hwnd, UINT Message, WPARAM wParam, LPARAM lParam) {
	int i_text1=1;
	int i_text2=1;
	int i_text3=1;
	int i_text4=1;
	int i_button1=3;
	int i_button2=3;
	int i_button3=3;
	int i_button4=3;


	switch(Message) {

		/* Upon destruction, tell the main thread to stop */
		case WM_DESTROY:
			PostQuitMessage(0);
			break;

		case  WM_CREATE:    // after case WM_destroy
		// 1. Creating Text box
			text_box1= CreateWindow(TEXT("EDIT"), TEXT(" myint"),WS_VISIBLE
			| WS_BORDER | WS_CHILD |ES_AUTOHSCROLL,
			20,10,200,25,hwnd, (HMENU)i_text1, NULL,NULL);

			text_box2= CreateWindow(TEXT("EDIT"), TEXT(" myBinary"),WS_VISIBLE
			| WS_BORDER | WS_CHILD |ES_AUTOHSCROLL,
			250,10,300,25,hwnd, (HMENU)i_text2, NULL,NULL);


			text_box3= CreateWindow(TEXT("EDIT"), TEXT(" myFloat"),WS_VISIBLE
			| WS_BORDER | WS_CHILD |ES_AUTOHSCROLL,
			20,200,200,25,hwnd, (HMENU)i_text3, NULL,NULL);

			text_box4= CreateWindow(TEXT("EDIT"), TEXT(" myBinary"),WS_VISIBLE
			| WS_BORDER | WS_CHILD |ES_AUTOHSCROLL,
			250,200,300,25,hwnd, (HMENU)i_text4, NULL,NULL);


			button1= CreateWindow(TEXT("BUTTON"), TEXT(" To Binary"),WS_VISIBLE
			| WS_BORDER | WS_CHILD,
			20,100,80,25,hwnd, (HMENU)i_button1, NULL,NULL);

			button2= CreateWindow(TEXT("BUTTON"), TEXT(" To Integer"),WS_VISIBLE
			| WS_BORDER | WS_CHILD,
			250,100,80,25,hwnd, (HMENU)i_button2, NULL,NULL);

			button3= CreateWindow(TEXT("BUTTON"), TEXT(" To Binary"),WS_VISIBLE
			| WS_BORDER | WS_CHILD,
			20,300,80,25,hwnd, (HMENU)i_button3, NULL,NULL);

			button4= CreateWindow(TEXT("BUTTON"), TEXT(" To float"),WS_VISIBLE
			| WS_BORDER | WS_CHILD,
			250,300,80,25,hwnd, (HMENU)i_button4, NULL,NULL);




			break;
			case WM_COMMAND:
				if (LOWORD(wParam)==i_button1)
            {MessageBox(hwnd,"I wil do it for you, don't worry","title",
			MB_OK|MB_ICONINFORMATION);
			char my_int_text[80];
			char buff[33];
			buff[32]='\0';
			int bufsize = GetWindowTextLength(text_box1) ;
            int i=GetWindowText(text_box1  ,  (char *)my_int_text,bufsize+1);
			int my_int = atoi(my_int_text);
			convert_to_bin(my_int,buff);	//convert to binary
			SetWindowText(text_box2, buff);
			} //button1


			if(LOWORD(wParam)==i_button2)
			{
				char buff[33];
				buff[32]='\0';
			int bufsize = GetWindowTextLength(text_box2) ;
            int i=GetWindowText(text_box2  ,  (char *)buff,bufsize+1);
            int my_int = back_to_int(buff);
            char int_text[10];
            itoa(my_int,int_text,9);
            SetWindowText(text_box1, int_text);
		}

            //float
            if (LOWORD(wParam)==i_button3)
            {MessageBox(hwnd,"I wil do it for you, don't worry","title",
			MB_OK|MB_ICONINFORMATION);
			char my_float_text[80];
			char buff[33];
			buff[32]='\0';
			int bufsize = GetWindowTextLength(text_box3) ;
            int i=GetWindowText(text_box3  ,  (char *)my_float_text,bufsize+1);
			float my_float = atof(my_float_text);
			floatToBinary(my_float,buff);	//convert to binary
			SetWindowText(text_box4, buff);
			} //button1

            if(LOWORD(wParam)==i_button4)
			{
				char buff[33];
				buff[32]='\0';
			int bufsize = GetWindowTextLength(text_box4) ;
            int i=GetWindowText(text_box4  ,  (char *)buff,bufsize+1);
            int my_int = back_to_int(buff);
            char int_text[10];
            itoa(my_int,int_text,9);
            SetWindowText(text_box3, int_text);

			}
		break;
		/* All other messages (a lot of them) are processed using default procedures */
		default:
			return DefWindowProc(hwnd, Message, wParam, lParam);
	}
	return 0;
}

/* The 'main' function of Win32 GUI programs: this is where execution starts */
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) {
	WNDCLASSEX wc; /* A properties struct of our window */
	HWND hwnd; /* A 'HANDLE', hence the H, or a pointer to our window */
	MSG msg; /* A temporary location for all messages */

	/* zero out the struct and set the stuff we want to modify */
	memset(&wc,0,sizeof(wc));
	wc.cbSize		 = sizeof(WNDCLASSEX);
	wc.lpfnWndProc	 = WndProc; /* This is where we will send messages to */
	wc.hInstance	 = hInstance;
	wc.hCursor		 = LoadCursor(NULL, IDC_ARROW);

	/* White, COLOR_WINDOW is just a #define for a system color, try Ctrl+Clicking it */
	wc.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
	wc.lpszClassName = "WindowClass";
	wc.hIcon		 = LoadIcon(NULL, IDI_APPLICATION); /* Load a standard icon */
	wc.hIconSm		 = LoadIcon(NULL, IDI_APPLICATION); /* use the name "A" to use the project icon */

	if(!RegisterClassEx(&wc)) {
		MessageBox(NULL, "Window Registration Failed!","Error!",MB_ICONEXCLAMATION|MB_OK);
		return 0;
	}

	hwnd = CreateWindowEx(WS_EX_CLIENTEDGE,"WindowClass","Caption",WS_VISIBLE|WS_OVERLAPPEDWINDOW,
		CW_USEDEFAULT, /* x */
		CW_USEDEFAULT, /* y */
		640, /* width */
		480, /* height */
		NULL,NULL,hInstance,NULL);

	if(hwnd == NULL) {
		MessageBox(NULL, "Window Creation Failed!","Error!",MB_ICONEXCLAMATION|MB_OK);
		return 0;
	}

	/*
		This is the heart of our program where all input is processed and
		sent to WndProc. Note that GetMessage blocks code flow until it receives something, so
		this loop will not produce unreasonably high CPU usage
	*/
	while(GetMessage(&msg, NULL, 0, 0) > 0) { /* If no error is received... */
		TranslateMessage(&msg); /* Translate key codes to chars if present */
		DispatchMessage(&msg); /* Send it to WndProc */
	}
	return msg.wParam;
}