Pascal. Case instead If - if-statement

Question

I m just trying to write my second (yes, it s absolutely new for me) teaching programm on Pascal. I ve made once, using "if", here it is:
program DemoBool;
Var A: Boolean ; B: Boolean ;
C:Integer ; D:Integer ;
I:Integer;
begin
write('Enter A(1/0): '); readln(I);
if (I= 1)
then A:=true else A:=false;
writeln(A);
write('Enter B(1/0): '); readln(I);
if I=1
then B:=true else B:=false;
writeln(B);
write('enter C: '); readln(C);
write('enter D: '); readln(D);
IF ((A=B) AND (C>D)=TRUE OR NOT A )
THEN IF ((TRUE<>A) AND (C-D<3))
THEN writeln('a=b, c>d, or not A=true, (true<>a and c-d<3)=true')
ELSE writeln('a=b, c>d, or not A=true, (true<>a and c-d<3)=false')
ELSE writeln('a<>b, c<d, or not A=false') ;
readln;
end.
And how can I use case instead if for latest conditions?..
Can I write new Var-s , F, F2- Boolean and then somehow, making this:
F:= ((A=B) AND (C>D)=TRUE OR NOT A ) ;
F2:= ((TRUE<>A) AND (C-D<3));
use Case?
It s really not easy for me, but hope, I can manage this task) sorry for my explanation. Thank you for attention

Answer 1

There are several improvments possible to your use of boolean, but this is normal since you learn.
1
if (I= 1) then A:=true else A:=false;
You can directly assign to A the comparison result of I equal to 1
A := (I = 1);
Which leads to better byte code, even without optimization (a TEST than a SETZ instruction). The Paren pair is just for readability.
2
IF ((A=B) AND (C>D)=TRUE OR NOT A )
You don't need to compare the result of boolean operation to true of false.
if ((a=b) and (c>d) or not a)
The expression statements (a=b) and (c>d) already evaluates to a Boolean.
3
If you want to use the case of expression, let's say to replace the end of the program:
case (A = B) and (C > D)) and A and (C - D < 3) of
true: writeln('yep');
false: writeln('nope');
end;
note that I use the simplified statements of lurker comment.

Answer 2

As far as I understood you insisted on using a case statement. Though I entirely agree with #lurker and suppose that case statement is not useful here I have the following proposal.
program DemoBool;
var
BitLogic: byte;
tmpb: byte;
A: Boolean;
B: Boolean;
C: Integer;
D: Integer;
I: Integer;
function GetBoolBit(const B: Boolean; Offset: byte): byte;
begin
if B then
begin
result := 1;
result := result shl Offset;
end
else
result := 0;
end;
begin
//input the values
BitLogic := GetBoolBit(A = B, 0);
tmpb := GetBoolBit(A, 1);
BitLogic := tmpb or BitLogic;//make comparison and store the result
// in bit-by-bit mode - every new boolean with the new offset
// the code is unscrolled here. We can optimize it writing the following instead:
// BitLogic := GetBoolBit(A, 1) or BitLogic;
tmpb := GetBoolBit(C > D, 2);
BitLogic := tmpb or BitLogic;
tmpb := GetBoolBit(C - D < 3, 3);
BitLogic := tmpb or BitLogic;
// we get the following the lower bit will store the first boolean - A=B
// the second - the second - A
// the third - C>D etc.
// the fourth - C-D<3 etc.
//now we can make an adequate case statement:
case BitLogic of
0: {00000000b}writeln('all false');
1: {00000001b}writeln('A=B');
2: {00000010b}writeln('A(=true)');
3: {00000011b}writeln('A and A=B');
4: {00000100b}writeln('C>D');
5: {00000101b}writeln('C>D and A=B');
6: {00000110b}writeln('C>D and A');
7: {00000111b}writeln('C>D and A and A=B');
8: {00001000b}writeln('C - D < 3');
9: {00001001b}writeln('C - D < 3 and A=B');
10:{00001010b}writeln('C - D < 3 and A');
11:{00001011b}writeln('C - D < 3 and A and A=B');
12:{00001100b}writeln('C - D < 3 and C>D');
13:{00001101b}writeln('C - D < 3 and C>D and A=B');
14:{00001110b}writeln('C - D < 3 and C>D and A');
15:{00001111b}writeln('C - D < 3 and C>D and A and A=B');
end;
end.
P.S. Check the logics of your if then else statements. There is a false decision: you decide that if not C > D then C < D. It is C <= D. I would advise you to read this SO answer as well.