glitch problem...

Hi. I want to know difference between two code , especially glitch problem.

I saw a two examples in the book and the book said first code has a glitch, but second code doesn't have the glitch, and show me the waveform editor picture.

why does the book says first code have a glitch, and second code doesn't have the glitch?

I want to know the reason why first code has glitch and second doesn't have!

first code!

LIBRARY IEEE;

USE IEEE.STD_LOGIC_1164.ALL;

ENTITY ex12_11 is

port(

ncp,nre : in std_logic;

q : buffer integer range 0 to 15);

end ex12_11;

ARCHITECTURE arc of ex12_11 is

begin

process(ncp,nre)

begin

if(nre='0' or q = 10) then

q<=0;

elsif(ncp'event and ncp='0') then

q<=q+1;

end if;

end process;

end arc;

second code

LIBRARY IEEE;

USE IEEE.STD_LOGIC_1164.ALL;

ENTITY ex12_12 is

port(

ncp,nrd : in std_Logic;

q : buffer integer range 0 to 15);

end ex12_12;

ARCHITECTURE arc of ex12_12 is

begin

process(ncp,nrd)

begin

if(nrd ='0') then

q<=0;

elsif(ncp'event and ncp='0') then

if(q=10) then

q<=0;

else q<=q+1;

end if;

end if;

end process;

end arc;

p.s

( is there any way to find a glitch in model_sim?

Is there any button to find glitch? Do I have to zoom in and see all the pulse one by one?)