shift and push question in perl Post: 302123939

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Top Forums Shell Programming and Scripting shift and push question in perl Post 302123939 by cbkihong on Wednesday 27th of June 2007 10:05:36 PM

06-27-2007

Registered User

Quote:

Originally Posted by hankooknara

2) not understanding how shift @last5 if @last5 > 5 works.. can somone let me know item by item please?

No, because it is the overall effect of the entire while() loop that causes the last 5 lines to be stored in the @last5 array variable, not due to that shift() function alone.

While each line is added to the array in each iteration, if the "shift() .... if ..." finds that more than 5 (maximum 6, actually) lines stored in the array, it will start removing a single line each time from the top so the count is maintained at 5. You can view this as a circular buffer. Of course, when the loop terminates, the items inside must be the last 5 lines read from the file (or may be less, if the file has < 5 lines).

If you still don't get it, put some print() in the loop to print the loop content in each iteration to see for yourself the change in content in action. Of course you can use debugger. Good only if you know how to use it, and the Perl debugger is, em, well .......

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LEARN ABOUT X11R4

xkbkeysymentry

XkbKeySymEntry(3)						   XKB FUNCTIONS						 XkbKeySymEntry(3)

NAME

       XkbKeySymEntry -  Returns the keysym corresponding to shift level shift and group grp from the two-dimensional array of keysyms for the key
       corresponding to keycode

SYNOPSIS

       KeySym XkbKeySymEntry macro ( xkb, keycode, shift, grp )
	     XkbDescPtr xkb;
	     KeyCode keycode;
	     int shift;
	     int grp;

ARGUMENTS

       - xkb  Xkb description of interest

       - keycode
	      keycode of interest

       - shift
	      shift level of interest

       - grp  group of interest

DESCRIPTION

       The key width and number of groups associated with a key are used to form a small two-dimensional array of KeySyms for a  key.  This  array
       may be different sizes for different keys. The array for a single key is stored as a linear list, in row-major order. The arrays for all of
       the keys are stored in the syms field of the client map. There is one row for each group associated with a key  and  one  column  for  each
       level. The index corresponding to a given group and shift level is computed as:

	    idx = group_index * key_width + shift_level

       The offset field of the key_sym_map entry for a key is used to access the beginning of the array.

       XkbKeySymEntry  returns	the  keysym corresponding to shift level shift and group grp from the two-dimensional array of keysyms for the key
       corresponding to keycode.

X Version 11							   libX11 1.2.1 						 XkbKeySymEntry(3)