Programming Perl, 4th Edition

getc

getc FILEHANDLE
getc

This function returns the next character from the input file attached to FILEHANDLE. It returns undef at end-of-file or if an I/O error was encountered. If FILEHANDLE is omitted, the function reads from STDIN.

This function is somewhat slow, but it’s occasionally useful for single-character input from the keyboard—provided you manage to get your keyboard input unbuffered. This function requests unbuffered input from the standard I/O library. Unfortunately, the standard I/O library is not so standard as to provide a portable way to tell the underlying operating system to supply unbuffered keyboard input to the standard I/O system. To do that, you have to be slightly more clever, and in an operating-system-dependent fashion. Under Unix you might say this:

if ($BSD_STYLE) {
    system "stty cbreak </dev/tty >/dev/tty 2>&1";
} else {
    system "stty", "–icanon", "eol", "\001";
}

$key = getc;

if ($BSD_STYLE) {
    system "stty –cbreak </dev/tty >/dev/tty 2>&1";
} else {
    system "stty", "icanon", "eol", "^@"; # ASCII NUL
}
print "\n";

This code puts the next character typed on the terminal in the string $key. If your stty program has options like cbreak, you’ll need to use the code where $BSD_STYLE is true. Otherwise, you’ll need to use the code where it is false. Determining ...