Why do all my programs use 100% CPU?

hamsterman (4538)
For example 
1
2
3
4
5
6
7
8
9
 
#include <windows.h>

int main(){
    POINT p;
    do{
        GetCursorPos(&p);
    }while(p.x>10);
    return 0;
}

Help please
mahlerfive (119)
Because it is the only program making use of the CPU at the time, so it is given 100% of the resources. Try running two of your programs at once. Or try running your program alongside some other program that is doing a lot of work.
Duthomhas (13282)
It is because you are constantly polling the cursor position (or whether or not there is keyboard input, etc) instead of letting windows tell you where it is.

I presume you are playing with a console application (and not a GUI application)? To get mouse events in a Win32 console application, assume the following:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
 
#include <windows.h>

const char ERR_NOT_A_CONSOLE[] =
  "You must run this program interactively in a console window.\n";

//-----------------------------------------------------------------------------
HANDLE hstdin;
HANDLE hstdout;
BOOL   done = FALSE;

//-----------------------------------------------------------------------------
void write( const char* message )
  {
  DWORD foo;
  WriteConsole(
    hstdout,
    (const void*)message,
    lstrlen( message ),
    &foo,
    NULL
    );
  }

//-----------------------------------------------------------------------------
COORD get_cursor_pos()
  {
  CONSOLE_SCREEN_BUFFER_INFO csbi;
  GetConsoleScreenBufferInfo( hstdout, &csbi );
  return csbi.dwCursorPosition;
  }

//-----------------------------------------------------------------------------
void set_cursor_pos( COORD pos )
  {
  SetConsoleCursorPosition( hstdout, pos );
  }

//-----------------------------------------------------------------------------
void key_event_handler( KEY_EVENT_RECORD event )
  {
  if (event.wVirtualKeyCode == VK_ESCAPE) done = TRUE;
  }

//-----------------------------------------------------------------------------
void mouse_event_handler( MOUSE_EVENT_RECORD event )
  {
  char message[ 100 ];
  COORD pos;
  pos = get_cursor_pos();
  wsprintf(
    message,
    "%3d %3d [%c][%c][%c]",
    event.dwMousePosition.X,
    event.dwMousePosition.Y,
    (event.dwButtonState & FROM_LEFT_1ST_BUTTON_PRESSED) ? 'x' : ' ',
    (event.dwButtonState & FROM_LEFT_2ND_BUTTON_PRESSED) ? 'x' : ' ',
    (event.dwButtonState & RIGHTMOST_BUTTON_PRESSED) ? 'x' : ' '
    );
  write( message );
  set_cursor_pos( pos );
  }

//-----------------------------------------------------------------------------
int main()
  {
  DWORD        mode;
  DWORD        count;
  INPUT_RECORD console_event;
  BOOL         blink = TRUE;

  // Validate the console
  hstdin  = GetStdHandle( STD_INPUT_HANDLE );
  hstdout = GetStdHandle( STD_OUTPUT_HANDLE );
  if (!GetConsoleMode( hstdin, &mode ))
    {
    WriteFile(
      GetStdHandle( STD_ERROR_HANDLE ),
      (const void*)ERR_NOT_A_CONSOLE,
      lstrlen( ERR_NOT_A_CONSOLE ),
      &count,
      NULL
      );
    return 1;
    }

  // Select raw input and mouse events
  SetConsoleMode( hstdin, ENABLE_MOUSE_INPUT );


  write( "Press Esc to quit.\n." );

  // Main loop
  while (!done)
    {
    if (WaitForSingleObject( hstdin, 350 ) == WAIT_OBJECT_0)
      {
      if (!ReadConsoleInput( hstdin, &console_event, 1, &count )) continue;

      switch (console_event.EventType)
        {
        case KEY_EVENT:
          key_event_handler( console_event.Event.KeyEvent );
          break;

        case MOUSE_EVENT:
          mouse_event_handler( console_event.Event.MouseEvent );
          break;

        }
      }

    blink = !blink;
    if (blink) write( "\b." );
    else       write( "\b " );
    }


  // All done
  SetConsoleMode( hstdin, mode );
  return 0;
  }

If you want the mouse to work, make sure that Properties --> Options --> Quick Edit Mode is OFF. I still don't know how to change that programmatically.

Here's a tutorial I found that you might like.
http://www.adrianxw.dk/SoftwareSite/index.html
helios (17607)
The reason regular programs don't use 100% CPU is because they spend most of the time either waiting for input (for example, a text editor), or inside a delay function (such as Sleep()).
The problem in your case is that you're constantly checking where the mouse is, while the user is not constantly moving the mouse around. I reckon there must be some function that waits for the user to perform some input. if there isn't, then at least you can wait a certain amount of time between each check. Even waiting 10 ms will lower CPU usage to about 0% (depending on the system).
Topic archived. No new replies allowed.