GPC supports Standard Pascal set operations. In addition it supports
the Extended Pascal set operation symmetric difference
(set1 >< set2
) operation whose result consists of those
elements which are in exactly one of the operannds.
It also has a function that counts the elements in the set: a := Card (set1).
In the following description, S1 and S2 are variables of set type, s is of the base type of the set.
S1 := S2
S1 + S2
S1 - S2
S1 * S2
S1 >< S2
S1 = S2
True
if
S1
has the same elements as S2
.
S1 <> S2
True
if
S1
does not have the same elements as S2
.
S1 < S2
S2 > S1
True
if
S1
is a strict subset of S2
.
S1 <= S2
S2 >= S1
True
if
S1
is a subset of (or equal to) S2
.
s in S1
s
and a set. Returns
boolean result. True
if s
is an element of S1
.
The following example demonstrates some set
operations. The results
of the operations are given in the comments.
program SetOpDemo; type TCharSet = set of Char; var S1, S2, S3: TCharSet; Result: Boolean; begin S1 := ['a', 'b', 'c']; S2 := ['c', 'd', 'e']; S3 := S1 + S2; { S3 = ['a', 'b', 'c', 'd', 'e'] } S3 := S1 * S2; { S3 = ['c'] } S3 := S1 - S2; { S3 = ['a', 'b'] } S3 := S1 >< S2; { S3 = ['a', 'b', 'd', 'e'] } S1 := ['c', 'd', 'e']; Result := S1 = S2; { False } Result := S1 < S2; { False } Result := S1 <= S2; { True } S1 := ['c', 'd']; Result := S1 <> S2; { True } Result := S2 > S1; { True } Result := S2 >= S1 { True } end.