This document deals with accepting function keys in an Extended Curses programming environment and has been tested against AIX 3.2.5.
Acquisition of certain key strokes can be problematic because terminals send mutli-byte strings for many of the non-alphanumeric keys. For example, the HFT produces 'ESC' [001q when Function Key 1 is pressed. Adding to the difficulty, the strings produced by the special keys is often different from one terminal type to another. Code development is made much simpler when the Extended Curses library is used to return to an integer value for each special key pressed independent of the terminal type.
This document includes a program which serves to illustrate the use of the Extended Curses library functions to achieve terminal independence and interpretation of multi-byte special key strings into integer values.
InfoExplorer, "General Programming Concepts", Chapter 2, "The Curses Library".
Strang, John. "Programming with curses", O'Reilly & Associates, Inc.
This item contains characters that may not print or display correctly on all systems. A flag line has been placed BENEATH each line that contains one or more of those characters. Flag lines can be identified by the characters "@@" in columns 64 and 65. The position of each unprintable or nondisplayable character is identified by one of the following letters contained in the flag line and located directly beneath that character.
A - left square bracket G - logical not B - right square bracket H - exclamation point C - left brace I - vertical bar D - right brace J - back slash E - percent sign K - tilde F - caret (circumflex) L - back quote (accent)
Provided below is a sample program that will accept a function key in the Base, Shift, or Ctrl state and print out the function key pressed. The function keys are recognized as follows:
Function Key Base Shift Ctrl
F1 F1 F13 F25
F2 F2 F14 F26
F3 F3 F15 F27
F4 F4 F16 F28
F5 F5 F17 F29
F6 F6 F18 F30
F7 F7 F19 F31
F8 F8 F20 F32
F9 F9 F21 F33
F10 F10 F22 F34
F11 F11 F23 F35
F12 F12 F24 F36
The sample program uses the following curses subroutines:
getch() csavetty(TRUE) extended(FALSE) cresetty(FALSE)
#define KEY_F0 0x180 /* function key - */ #define KEY_F(n) (KEY_F0+(n))/* reserve 128 values */
It is not necessary to use csavetty() in the sample program. Input modes could be set up with their respective subroutines. However, keypad(TRUE) and nonl() must be used in order to retrieve function keys on the IBM 3151.
The following program has been tested with the IBM 3151 Model 310, a vt100 emulator, the HFT, and aixterm. Please note that not all terminals support the Base, Shift, and Ctrl states of function keys (e.g. IBM 3151 does not support Ctrl-Function Keys and VT100 only has F1 - F4 keys).
/********************************************************
* funkey.c - Prints out the function key pressed. *
* Recognizes F1 - F36: *
* F1 - F12 *
* Shift F1 - Shift F12 (= f13 - f24) *
* Ctrl F1 - Ctrl F12 (= f25 - f36) *
* To Compile: cc -o funkey.c -0 funkey -lcur *
* To Run: funkey *
********************************************************/
#include<cur01.h>
#include<cur02.h>
#define ESC 0x1b
main() {
C @@
int retval;
/* --- initialize the curses control structures, etc. */
initscr();
/* --- preserve the current state of the tty */
csavetty(TRUE);
/* --- turn multibyte processing off */
extended(FALSE);
/* --- enable horizontal scrolling */
scrollok (stdscr,TRUE);
printw("Enter a function key (ESC to exit)
");
refresh();
J @@
/* --- get keys - quit on ESCape - display function key value */
while( (retval = getch()) != ESC ) {
H C @@
if( retval > KEY_F(0) && retval < KEY_F(37) )
printw("*** F%d ***
",retval - KEY_F(0));
E J @@
else
switch(retval ) {
C @@
case KEY_UP: printw("*** Up Arrow ***
"); break;
J @@
case KEY_DOWN: printw("*** Down Arrow ***
"); break;
J @@
case KEY_LEFT: printw("*** Left Arrow ***
"); break;
J @@
case KEY_RIGHT: printw("*** Right Arrow ***
"); break;
J @@
case KEY_NPAGE: printw("*** Next Page ***
"); break;
J @@
case KEY_PPAGE: printw("*** Previous Page ***
"); break;
J @@
case KEY_HOME: printw("*** Home ***
"); break;
J @@
case KEY_END: printw("*** End ***
"); break;
J @@
case KEY_DELETE: printw("*** Delete ***
"); break;
J @@
case KEY_IC: printw("*** Insert ***
"); break;
J @@
default: printw("Some other character
"); break;
J @@
}
D @@
refresh();
}
D @@
/* --- reset the tty to its original state */
cresetty(FALSE);
endwin();
}
D @@
[ Doc Ref: 90605203014666 Publish Date: Nov. 09, 1999]