The IDL_GetKbrd() function returns the character code of the next available character from IDL_STDIN_UNIT:

int IDL_GetKbrd(int should_wait)


Set this argument to TRUE if IDL_GetKbrd() should wait for a key to be struck, FALSE otherwise.

If should_wait is FALSE and no input characters are waiting in the input stream, IDL_GetKbrd() returns NULL. Otherwise, it waits until a key is struck (if necessary) and then returns its ASCII value. This function will generate an error and return to the interpreter if IDL_STDIN_UNIT is not a terminal.