a letter character else when Alt or Shift key + a letter key is pressed

What software let us have a letter character else when Alt or Shift key + a letter key is pressed for about 13-15 keys?

Up to the point that is creating new input method: a reliable single (right) handed keyboard capability

if Shift key + letter, the shift function is done by Ctrl+Shift to register upper case letter Please give correct solution
its a different signal from the hardware when you use the shift keys (shift, ctrl, alt, win/apple/other, numlock, whatever). unfortunately cin does not recognize this fact, and so you have to use either low level assembly code or a third party library (which is using inline assembly code, most likely). There may be a way to get the real signal from the keyboard, but I do not know how to do it easily.
I don't think you can get a "real signal from the keyboard" directly in a normal user-space program. Whether you are programming in C/C++ or in Assembler language doesn't make a difference in this regard. I think you would have to write a kernel-module and load it into the Linux kernel in order to get this kind of "low-level" hardware access. But that would require a deep understanding of kernel hacking and the hardware.

(and, of course, it would be very hardware-specific and non-portable)

Fortunately, the Linux kernel already provides an user-space interface to the keyboard, as a device file:
/dev/input/by-path/<youir_name_here>-kbd

Minimal example:
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#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <linux/input.h>

#define KEYMAP_SIZE ((KEY_MAX / 8) + 1)

int main()
{
	char key_map[KEYMAP_SIZE];
	FILE *kbd = fopen("/dev/input/by-path/platform-i8042-serio-0-event-kbd", "r");
	if (!kbd)
	{
		fputs("Error Failed to open keyboard device!\n", stderr);
		return EXIT_FAILURE;
	}
	for (;;)
	{
		memset(key_map, 0, sizeof(key_map));
		ioctl(fileno(kbd), EVIOCGKEY(sizeof(key_map)), key_map);
		for (size_t i = 0; i < KEYMAP_SIZE; ++i)
		{
			printf("%02X", key_map[i]);
		}
		puts("\n");
		usleep(100000);
	}
	return EXIT_SUCCESS;
}


Above code dumps the current state of all keys (including Shift, Ctrl and Alt), in regular intervals. If you are interested in a specific key, then you just need to extract the proper bit from the key_map array.

Note: You may need to run this with sudo, otherwise permission to the keyboard device may be denied.
Last edited on
hah, I had forgotten that existed -- too little unix time last few years.
directinput or whatever it morphed into may support 'close enough' for windows; it may not do it all (?) but it traps the special keys and even maps numeric pad vs normal keys or which (left or right) shifter you hit.
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