key_shifts - Bitmask containing the current state of modifier keys. Allegro game programming library.

       Bitmask  containing  the current state of shift/ctrl/alt, the special Windows keys, and the accent escape
       characters. Wherever possible this value will be updated  asynchronously,  but  if  keyboard_needs_poll()
       returns  TRUE, you must manually call poll_keyboard() to update it with the current input state. This can
       contain any of the flags:

          KB_SHIFT_FLAG
          KB_CTRL_FLAG
          KB_ALT_FLAG
          KB_LWIN_FLAG
          KB_RWIN_FLAG
          KB_MENU_FLAG
          KB_COMMAND_FLAG
          KB_SCROLOCK_FLAG
          KB_NUMLOCK_FLAG
          KB_CAPSLOCK_FLAG
          KB_INALTSEQ_FLAG
          KB_ACCENT1_FLAG
          KB_ACCENT2_FLAG
          KB_ACCENT3_FLAG
          KB_ACCENT4_FLAG

       Example:

          if (key[KEY_W]) {
             if (key_shifts & KB_SHIFT_FLAG) {
                /* User is pressing shift + W. */
             } else {
                /* Hmmm... lower case W then. */
             }
          }

       key_shifts - Bitmask containing the current state of modifier keys. Allegro game programming library.

install_keyboard(3alleg4), poll_keyboard(3alleg4), key(3alleg4), excamera(3alleg4), exkeys(3alleg4)

Allegro                                           version 4.4.3                              key_shifts(3alleg4)

#include<allegro.h>externvolatileintkey_shifts;