TP3/shell/tests/fixtures/t48_strcmp.pas

{ t48_strcmp: string comparison, all six operators, string VARIABLES.
  String subscripts s[i] are TChar, so s[i] = c is a char compare; this
  pins string-vs-string, which is cmpstr (TPSRC2) / vcompare (TPSRC9).

  Each block weights the six operators 1,2,4,8,16,32 for =,<>,<,<=,>,>= so
  the printed sum is a SIGNATURE of which ones held:

    41  equal (1+8+32)          14  left < right (2+4+8)
    50  left > right (2+16+32)

  A plain +1 per operator cannot tell < from >: both come to 3, and so does
  every other unequal pair, because [a<b]+[a<=b]+[a>b]+[a>=b] is always 2.
  That is not a hypothetical - it is how the first version of this fixture
  reported 3,3,3,3 while every ordering comparison was inverted. }
program t48_strcmp (input, output);
var
   a, b : string[8];
   n    : integer;
begin
   a := 'abc';
   b := 'abc';
   n := 0;
   if a =  b then n := n + 1;
   if a <> b then n := n + 2;
   if a <  b then n := n + 4;
   if a <= b then n := n + 8;
   if a >  b then n := n + 16;
   if a >= b then n := n + 32;
   writeln(n);                      { 41: =, <=, >= }

   b := 'abd';                      { same length, differs at byte 3 }
   n := 0;
   if a =  b then n := n + 1;
   if a <> b then n := n + 2;
   if a <  b then n := n + 4;
   if a <= b then n := n + 8;
   if a >  b then n := n + 16;
   if a >= b then n := n + 32;
   writeln(n);                      { 14: 'abc' < 'abd' }

   b := 'ab';                       { b is a strict PREFIX of a }
   n := 0;
   if a =  b then n := n + 1;
   if a <> b then n := n + 2;
   if a <  b then n := n + 4;
   if a <= b then n := n + 8;
   if a >  b then n := n + 16;
   if a >= b then n := n + 32;
   writeln(n);                      { 50: longer means greater }

   a := 'ab';                       { a is a strict PREFIX of b }
   b := 'abc';
   n := 0;
   if a =  b then n := n + 1;
   if a <> b then n := n + 2;
   if a <  b then n := n + 4;
   if a <= b then n := n + 8;
   if a >  b then n := n + 16;
   if a >= b then n := n + 32;
   writeln(n);                      { 14: shorter means less }

   b := '';                         { the empty string: min(lenL,lenR) = 0,
                                      the JCXZ arm of cmpstr's loop }
   n := 0;
   if a =  b then n := n + 1;
   if a <> b then n := n + 2;
   if a <  b then n := n + 4;
   if a <= b then n := n + 8;
   if a >  b then n := n + 16;
   if a >= b then n := n + 32;
   writeln(n);                      { 50: 'ab' > '' }

   b := 'abc';                      { all six as VALUES, not branches }
   writeln(a = b, ' ', a <> b, ' ', a < b, ' ', a <= b, ' ',
                   a > b, ' ', a >= b)
end.