Error Message! Could someone help!

[Bobbyunccstudent]

I continue getting this error message. I have tried several different things but cannot seem to figure out how to fix this error. Could someone help.
ERROR:HDLParsers:164 - "/afs/uncc.edu/usr/k/jmoone11/linux/apps/xilinx/Project4/Project4.vhd" Line 48. parse error, unexpected CHARACTER_LITERAL, expecting THEN

This is some of the program so far. I numbered a few lines so you would know approx where the error is located.

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

-- Uncomment the following library declaration if using
-- arithmetic functions with Signed or Unsigned values
--use IEEE.NUMERIC_STD.ALL;

-- Uncomment the following library declaration if instantiating
-- any Xilinx primitives in this code.
--library UNISIM;
--use UNISIM.VComponents.all;

entity Project4 is
    Port ( Clock : in  STD_LOGIC;
           Resetn : in  STD_LOGIC;
           R : in  STD_LOGIC;
           S : in  STD_LOGIC;
           T : in  STD_LOGIC;
           Z : out  STD_LOGIC);
end Project4;

architecture Behavioral of Project4 is
type state_type is (A, B, C, D);
signal y : State_type;

45.begin
46.Process (Resetn, clock, )
begin
47.If resetn '0' then y<= 'A';
48.Else If ( clock' Event and Clock = '1') Then
49.Case y is
50.when A => 
51.If s = '1' and T = '1' then y <= A;
52.else If s = '1' and T = '0' then y <= B;
else If s = '0' then y <= C;
else If S= '0'; End If;

When B=> 
If R= '0' then y<=B;
Else If R='1' the y<=C;

when c=> 
If R='0' and T='0' then y<=B;
else if R='1' and T='1' then y<=B;
else if R='1' and T='0' then y<=A;
else if R='0' and T='1' then y<=D;
when D=>
If R='0' then y<=A;
else y<=D; end if
end case;
end if;
end process;



end Behavioral;

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I numbered the lines incorrectly sorry. It starts at 45 but I skipped the begin it should 47 and so on.

 

[jayanth.devarayanadurga]

---

Code C - [expand]
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else S= '0'; End If;
 
When B=> 
If R = '0' then y <= B;
Else If R = '1' then y <= C;

---

 

[Bobbyunccstudent]

I dont understand

- - - Updated - - -

Ifigured the error out I didnt have a =. I had If resetn '0' then y<= 'A'; it should be If resetn= '0' then y<= 'A';

47.If resetn '0' then y<= 'A';
48.Else If ( clock' Event and Clock = '1') Then
49.Case y is
50.when A => 
51.If s = '1' and T = '1' then y <= A;
52.else If s = '1' and T = '0' then y <= B;
else If s = '0' then y <= C;
else If S= '0'; End If;