Data conversion-Delphi online data collection (Source: in case of a blog)

About Lo, hi, loword, hiword

Cardinal is a 4-byte unsigned integer. First, let's look at the number of examples:

Cardinal examples:	4277991664
By byte:	Fourth byte	Third byte	Second byte	First byte
Binary:	11111110	11111100	11111000	11110000
Hexadecimal:	Fe	FC	F8	F0
Decimal:	254	252	248	240
Divided by two bytes:	High dual		Two lower
Binary:	1111111011111100		1111100011110000
Hexadecimal:	FEFC		F8f0
Decimal:	65276		63728

// You can use the lo function to extract its low byte (that is, the first byte) const C: Cardinal = 4277991664; begin showmessagefmt ('% d ', [Lo (c)]); {240} end;
 // Actually, the lo function is not used. You can use byte type conversion to obtain the first byte const C: Cardinal = 4277991664; begin showmessagefmt ('% d ', [byte (c)]); {240} end;
 // The Hi function is used to obtain the high byte. In fact, it is used to obtain the second byte const C: Cardinal = 4277991664; begin showmessagefmt ('% d', [HI (c)]); {248} end;
 // If you want to get the lower two digits, it seems that there should be a loword function; it does, but it is not a function, it is just a alias for the word type. const C: Cardinal = 4277991664; begin showmessagefmt ('% d', [loword (c)]); {63728} showmessagefmt (' % d ', [word (c)]); {63728} end;
 //HiwordThe function is to extract the const C: Cardinal = 4277991664; begin showmessagefmt ('% d ',[Hiword(C)]); {65276} end;
 

Loword andHiwordPurpose:

For example, the mouse position is stored in the Message Parameter lparam of a mouse message. lparam is 4 bytes, and its low-two-digit storage is X and the high-two-digit storage is y...

In this example:

ProgramProject1;UsesWindows, messages; {custom process for wm_lbuttondown message call}ProcedureOnlbuttondown (H: hwnd );VaRBrushhandle: hbrush; rect: trect;BeginGetclientrect (H, rect); {get client rectangle} brushhandle: = createsolidbrush (RGB (255, 0, 0); {create red brush} fillrect (getdc (H), rect, brushhandle); {fill customer zone} deleteobject (brushhandle); {Delete brush}End; {Custom process for wm_lbuttonup message call}ProcedureOnlbuttonup (H: hwnd );VaRRect: trect;BeginGetclientrect (H, rect); {obtain the rectangle of the customer region} invalidaterect (H, @ rect, true); {invalidate the customer region and force re-painting}End; {Custom process for wm_mousemove message call}ProcedureOnmousemove (H: hwnd; lparam: integer );VaRPT: tpoint; Buf:Array[0 .. 255]OfChar;BeginPT. x: = loword (lparam); {the lower two digits in lparam are X coordinates} PT. y: = hiword (lparam); {the height two digits in lparam are Y coordinates} wvsprintf (BUF, '% d, % d', @ pt ); {format to buffer} setwindowtext (H, Buf); {display in title}End;FunctionWndproc (WND: hwnd; MSG: uint; wparam: integer; lparam: integer): integer;Stdcall;BeginResult: = 0;CaseMSGOfWm_lbuttondown: onlbuttondown (WND); {message with the left mouse button pressed} wm_lbuttonup: onlbuttonup (WND); {message with the left mouse button lifted} wm_mousemove: onmousemove (WND, lparam ); {cursor-moving message, coordinate position in lparam} wm_destroy: postquitmessage (0 );ElseResult: = defwindowproc (WND, MSG, wparam, lparam );End;End;FunctionRegmywndclass: Boolean;VaRCLS: twndclass;BeginCls. Style: = cs_hredrawOrCs_vredraw; Cls. lpfnwndproc: = @ wndproc; Cls. cbclsextra: = 0; Cls. cbwndextra: = 0; Cls. hinstance: = hinstance; Cls. hicon: = 0; Cls. hcursor: = loadcursor (0, idc_arrow); Cls. hbrbackground: = hbrush (color_window + 1); Cls. lpszmenuname: =Nil; Cls. lpszclassname: = 'mywnd'; Result: = registerclass (CLS) <> 0;End; {Program entry}ConstTit = 'new form'; Ws = ws_overlappedwindow; X = 100; y = 100; W = 300; H = 180;VaRHwnd: thandle; MSG: tmsg;BeginRegmywndclass; hwnd: = createwindow ('mywnd', tit, WS, X, Y, W, H, 0, 0, hinstance,Nil); Showwindow (hwnd, sw_shownormal); updatewindow (hwnd );While(Getmessage (MSG, 0, 0, 0 ))Do  BeginTranslatemessage (MSG); dispatchmessage (MSG );End;End.