Check If Arrow Key Is Pressed

How to detect that someone has pressed up, down, left, or right arrow key ?

I  used  getch(); but the integer that I got is 244 for all those 4 keys.
I also tried calling getch(); twice because someone told me that when I press
special keys, integer 0 will be returned first, then the 2nd getch(); will return
the true value. This doesn't work either.

Is getch() standard for C++? In which library getch() is? conio.h or stdio.h ?

Someone gave me this code but it didn't work.

  int ch = getch();
  if(ch == 0) {
      ch = getch();      // retrieve the second byte
        switch (ch) {
            case UP_ARROW:
                // do some code
                break;
            case DOWN_ARROW:
                // do some code;
                break;
            case LEFT_ARROW:
                // do some code;
                break;
            case F1:
                // do some code;
                break;
            case F2:
                // do some code;
                break;
             // ... etc ...
        }                        
    }
bubblebobbleAsked:
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

x
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

galkinCommented:
What platform are you developing on?
0
q2guoCommented:
the variable ch should be delcared as a char
so, line
int ch = getch();
should read
char ch = getch();

Also, remember to include the header file conio.h.
by the way, what did you set constant LEFT_ARROW
UP_ARROW, RIGHT_ARROW, DOWN_ARROW.  They should equal to
75 72 77 80 respectively
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
ozoCommented:
No, getch() is actually an int
0
OWASP Proactive Controls

Learn the most important control and control categories that every architect and developer should include in their projects.

q2guoCommented:
ozo, I tried on my computer, it worked out.
0
bubblebobbleAuthor Commented:
q2guo, I haven't changed ch type yet, but getch() should return int. Here is what MSVC help said

Get a character from the console without echo (_getch) or with echo (_getche).
int _getch( void );
int _getche( void );

The _getch function reads a single character from the console without echoing. _getche reads a single character from the console and echoes the character read. Neither function can be used to read CTRL+C. When reading a function key or an arrow key, _getch and _getche must be called twice; the first call returns 0 or 0xE0, and the second call returns the actual key code.

Also, what is the different between getch() and getchar() ?? Which one is standard?
0
q2guoCommented:
Are you using Visual C++??
0
bubblebobbleAuthor Commented:
yes and also I tested my code using gnu c++
0
vsinhaCommented:
There are three functions normally used to get char. from the console: getc, getch and getchar.
getchar() is equivalent to getc(stdin)
getc(stream) reads a character from a stream
getch() is different.

getch() is used [together with ungetch()] when it is necessary to 'put back' characters into the stream. Thse two functions work by using a common buffer for the characters.

you could try using getchar() instead of getch().
0
ozoCommented:
q2guo, I didn't mean that char won't work, I meant that the int was not a problem.
getchar and is part of the ANSI C standard, and so should be portable, while getch is not.
On the other hand, getchar makes no particular guarantees about buffering or echoing.
THe ANSI standard function to put back a getc(FILE *stream) is ungetc(int c,FILE *stream)
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
C++

From novice to tech pro — start learning today.