getch

Syntax

#include "graphics.h"
int getch(void);

Description

The getch function is available in the winbgim implementation of BGI graphics. You do not need to include conio.h; just include graphics.h. The function reads one character from the keyboard and returns its ASCII value (without waiting for a return key). In order to work, the user must click in the graphics window (i.e., the Windows focus must be in the graphics window). For special keys, the getch function first returns ASCII 0. The next call will then return one of these special keys:

  #define KEY_HOME       71
  #define KEY_UP         72
  #define KEY_PGUP       73
  #define KEY_LEFT       75
  #define KEY_CENTER     76
  #define KEY_RIGHT      77
  #define KEY_END        79
  #define KEY_DOWN       80
  #define KEY_PGDN       81
  #define KEY_INSERT     82
  #define KEY_DELETE     83
  #define KEY_F1         59
  #define KEY_F2         60
  #define KEY_F3         61
  #define KEY_F4         62
  #define KEY_F5         63
  #define KEY_F6         64
  #define KEY_F7         65
  #define KEY_F8         66
  #define KEY_F9         67

Return Value

The ASCII value of a key that has been pressed.

See also

kbhit

Example

#include "graphics.h"
#include <stdio.h>      // Provides sprintf
#include <iostream.h>   // Provides cout

void outintxy(int x, int y, int value);

int main( )
{
    int i;
    char c;

    // Initialize the graphics window.
    init_window(400, 300);

    // Convert some numbers to strings and draw them in graphics window:
    outtextxy(10, 10, "Here are some numbers:");
    for (i = 10; i <= 100; i += 10)
        outintxy(20, i+10, i);

    // Get some characters from the keyboard until an X is typed:
    outtextxy(20, 130, "Click in this graphics window,");
    outtextxy(20, 140, "and then press arrow keys.");
    outtextxy(20, 150, "Watch the console window while pressing.");
    outtextxy(20, 160, "Press X to exit.");
    do
    {
        c = (char) getch( );
        if (c != 0)
            cout << "That is ASCII value: " << (int) c << endl;
        else
        {   // Process one of the special keys:
            c = (char) getch( );
            switch (c)
            {
                case KEY_HOME:    cout << "Home key."   << endl; break;
                case KEY_UP:      cout << "Up key."     << endl; break;
                case KEY_PGUP:    cout << "PgUp key."   << endl; break;
                case KEY_LEFT:    cout << "Left key."   << endl; break;
                case KEY_CENTER:  cout << "Center key." << endl; break;
                case KEY_RIGHT:   cout << "Right key."  << endl; break;
                case KEY_END:     cout << "End key."    << endl; break;
                case KEY_DOWN:    cout << "Down key."   << endl; break;
                case KEY_PGDN:    cout << "PgDn key."   << endl; break;
                case KEY_INSERT:  cout << "Insert key." << endl; break;
                case KEY_DELETE:  cout << "Delete key." << endl; break;
                case KEY_F1:      cout << "F1 key."     << endl; break;
                case KEY_F2:      cout << "F2 key."     << endl; break;
                case KEY_F3:      cout << "F3 key."     << endl; break;
                case KEY_F4:      cout << "F4 key."     << endl; break;
                case KEY_F5:      cout << "F5 key."     << endl; break;
                case KEY_F6:      cout << "F6 key."     << endl; break;
                case KEY_F7:      cout << "F7 key."     << endl; break;
                case KEY_F8:      cout << "F8 key."     << endl; break;
                case KEY_F9:      cout << "F9 key."     << endl; break;
                default: cout << "Unknown extended key." << endl;
            }
        }
    }   while ((c != 'x') && (c != 'X'));

    closegraph( );
}

void outintxy(int x, int y, int value)
{
   char digit_string[20];
   sprintf(digit_string, "%d", value);
   outtextxy(x, y, digit_string);
}