what does this code do?

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C#

getkey()
{
union REGS i,o;
i.h.ah=0;
int86(22,&i,&o);
return o.h.ah;
}
main()
{
int k=getkey();
}

Posted 10-Oct-10 3:55am

DhanashreeRamya

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3 solutions

Solution 3

As Griff said, it uses the BIOS to read a keystroke.

Second, the most important point is that it doesn't work on XP. Oh I know, you've compiled your code and it gives an answer but what you're actually doing is compiling it for DOS and running the program under NTVDM (which is the real mode DOS emulator that's been shipped with Windows since NT 3.1 came out yonks ago).

So... (a) bin the antique compiler you're using. 64 bit versions of windows can't run DOS applications so sooner or later "this code works fine" will become "unsupported 16 bit application."

(b) when you've got a decent compiler (VC++ or gcc are both good) then look up how you do I/O. Don't grope around with code from 1991 - find out how modern C and C++ programs work and see how they do it portably.

Cheers,

Ash

Posted 10-Oct-10 6:14am

Aescleal

Updated 10-Oct-10 8:20am

v2

Solution 4

If you just want get the input character.

This code snippet would be sufficient:

C

main()
{
    int k=getchar();
    printf("%d\n",k);
}

Posted 10-Oct-10 6:23am

Zhan Zongru

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OriginalGriff · Accepted Answer · 2010-10-10T04:01:00

Solution 1

It calls BIOS interrupt number 22 to fetch keystrokes. To be honest, I wouldn't use it - use getch instead.
Hardware access via in86 is severely restricted in XP and higher, or in Linux in any compatible way.

Posted 10-Oct-10 4:01am

OriginalGriff

Comments

Sandeep Mewara 10-Oct-10 12:16pm

Comment from OP:
Answer 2
Accept Answer Reject Answer

thanks for your help.but now next question arises is how to use getch instead of this code in my program..this code works fine on XP and gives output as k=28.
waiting for your reply....
thanks in advance....