C - Pruebas de entrada para el carácter CTRL +

Question

se preguntaba cómo podía probar la entrada que se guarda en una matriz de caracteres como ...

   char input[INPUT_SIZE];

y usando

fgets(input,INPUT_SIZE,stdin);

Para obtener la entrada del usuario, pero se preguntaba cómo podría usar una instrucción IF para probar si la entrada de los usuarios ha sido, por ejemplo, ctrl + d o cualquier ctrl + anykey?

Intenté usar el valor ASCCI como este .. es un ejemplo para probar CTRL D

  if(result = 'EOT') {printf("EOT");}

El resultado es una matriz de caracteres también.

Answer 1

You can only test Ctrl+d as your read returning EOF, see the manual of your read to have more info on this, but generally it returns 0. Same goes for Ctrl+c, as both are sending signals to your program.

For other Ctrl+key combinations, it highly depends on your system.

On linux Ctrl+a and Ctrl+e in a shell or emacs will move you to the beginning or the end / beginning of the line respectively.

The easiest to get what you want is to write a small program using read, unbuffered (see ioctl), with a 8-bytes buffer, and dump your read bytes each time you exit the read.

int nbr;
int i;
char buf[8];

nbr = 42;
while (nbr > 0)
{
  nbr = read(0, buf, 8);
  i = 0;
  while (i < nbr)
    printf("%x ", buf[i++]);
  printf("\n");
}

You will have the hex version of the ctrl+key received sequences. Likely to begin with \ESC or \033 (the escape character sequence). For example the arrow-up key looks like \033[A