Continue when a certain key is pressed/get pressed key

[coding4fun]

Hi. I'm kind of new to C++ and I was wondering if it's possible to make a program pause until a certain key is pressed. (I don't mean any key, I mean a certain key.

Also, is it possible to set a parameter's value to the key pressed?
I use Windows XP and my compiler is Visual C++ 2010 professional.

Thanks!

[freddie1]

I'm surprised nobody answered you coding4fun. That's easy to do. When a key is pressed, a key code is generated by the keyboard driver. There are ways to obtain this key code using the C Standard Library functions, the C++ Standard Library functions, and the Windows Api. For example, the Asci code (decimal) of the numeric zero key is 48. I havn't played with this stuff in awhile, but was quickly able to dig this up for you. There are many other ways to do it...

//Main.cpp
#include <stdio.h>
#include <conio.h>
#include <string.h>


typedef struct KEY
{
 bool blnKeyPressed;   //1 byte
 bool blnExtended;     //1 byte
 char ch;              //1 byte
 char code;            //1 byte
}KEY;


void Inkey(KEY& k)
{
 int ch;

 memset(&k,0,4);
 if(_kbhit())
 {
    ch=getch();
    if(ch==0x00||ch==0xE0)
    {
       k.blnExtended=true,  k.blnKeyPressed=true;
       k.ch='\0',           k.code=getch();
    }
    else
    {
       k.blnExtended=false, k.blnKeyPressed=true;
       k.ch=(char)ch,       k.code=(char)ch;
    }
 }
}


int main(void)
{
 KEY key;

 printf("key.blnKeyPressed\tkey.blnExtended\t\tkey.ch\t\tkey.code\n");
 printf("========================================================================\n");
 while(1)
 {
  Inkey(key);
  if(key.blnKeyPressed)
  {
     if(key.code==13||key.code==27)
        break;
     printf("%u\t\t\t%u\t\t\t%c\t\t%u\n",key.blnKeyPressed,key.blnExtended,key.ch,key.code);
  }
 };

 return 0;
}

Compile and run the program as a console program. Any key you hit will show up in the display. You can end the program by hitting the [ENTER] key (13) or the [ESCAPE] key (27). Hope this helps!

[freddie1]

Here's an even better one for you. It not only shows keys pressed, but mouse movements too!. It is fairly advanced though, and uses the kernel functions in the Windows Api. Hit [ESCAPE] to exit.

#include <windows.h>
#include <stdio.h>

int main(void)
{
 HANDLE hStdInput,hStdOutput;
 INPUT_RECORD ir[128];
 bool blnLoop=true;
 DWORD nRead;
 COORD xy;
 UINT i;

 hStdInput=GetStdHandle(STD_INPUT_HANDLE);
 hStdOutput=GetStdHandle(STD_OUTPUT_HANDLE);
 SetConsoleMode(hStdInput,ENABLE_MOUSE_INPUT|ENABLE_EXTENDED_FLAGS);
 FlushConsoleInputBuffer(hStdInput);
 do
 {
   if(WaitForSingleObject(hStdInput,INFINITE)==WAIT_TIMEOUT)
      break;
   else
   {
      ReadConsoleInput(hStdInput,ir,128,&nRead);
      for(i=0;i<nRead;i++)
      {
          switch(ir[i].EventType)
          {
           case KEY_EVENT:
             if(ir[i].Event.KeyEvent.wVirtualKeyCode==VK_ESCAPE)
                blnLoop=false;
             else
             {
                xy.X=0;xy.Y=0;
                SetConsoleCursorPosition(hStdOutput,xy);
                printf
                (
                 "AsciiCode = %d: symbol = %c\n",
                 ir[i].Event.KeyEvent.uChar.AsciiChar,
                 ir[i].Event.KeyEvent.uChar.AsciiChar
                );
             }
             break;
           case MOUSE_EVENT:
             xy.X=0, xy.Y=1;
             SetConsoleCursorPosition(hStdOutput,xy);
             printf
             (
              "%.3d\t%.3d\t%.3u",
              ir[i].Event.MouseEvent.dwMousePosition.X,
              ir[i].Event.MouseEvent.dwMousePosition.Y,
              (unsigned int)ir[i].Event.MouseEvent.dwButtonState & 0x07
             );
             break;
          }//end switch
      }//end for
   }//end if
 }//end do
 while(blnLoop==true);

 return 0;
}

[coding4fun]

Awesome, thanks! Both programs work!