Added set operations and example

examples/set_ops.c

@@ -0,0 +1,88 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "../src/macro_collections.h"
+
+// change to hashset to have the same effects
+COLLECTION_GENERATE(TREESET, PUBLIC, set, set, , , int)
+
+void print_set(set *s)
+{
+    size_t index;
+    int result;
+    set_iter iter;
+    set_iter_new(&iter, s);
+    for (set_iter_tostart(&iter); !set_iter_end(&iter);)
+    {
+        set_iter_next(&iter, &result, &index);
+        if (index == 0)
+            printf("[ %2d, ", result);
+        else if (index == s->count - 1)
+            printf("%2d ]\n", result);
+        else
+            printf("%2d, ", result);
+    }
+}
+
+int intcmp(int a, int b)
+{
+    return a - b;
+}
+
+int main(int argc, char const *argv[])
+{
+    set *set1 = set_new(intcmp);
+    set *set2 = set_new(intcmp);
+
+    for (int i = 1; i <= 20; i++)
+        set_insert(set1, i);
+
+    for (int i = 11; i <= 30; i++)
+        set_insert(set2, i);
+
+    set *set3 = set_union(set1, set2);
+
+    print_set(set1);
+    printf("UNION\n");
+    print_set(set2);
+    printf("=\n");
+    print_set(set3);
+
+    printf("\n\n");
+
+    set *set4 = set_intersection(set1, set2);
+
+    print_set(set1);
+    printf("INTERSECTION\n");
+    print_set(set2);
+    printf("=\n");
+    print_set(set4);
+
+    printf("\n\n");
+
+    set *set5 = set_difference(set1, set2);
+
+    print_set(set1);
+    printf("DIFFERENCE\n");
+    print_set(set2);
+    printf("=\n");
+    print_set(set5);
+
+    printf("\n\n");
+
+    set *set6 = set_symmetric_difference(set1, set2);
+
+    print_set(set1);
+    printf("SYMMETRIC DIFFERENCE\n");
+    print_set(set2);
+    printf("=\n");
+    print_set(set6);
+
+    set_free(set1);
+    set_free(set2);
+    set_free(set3);
+    set_free(set4);
+    set_free(set5);
+    set_free(set6);
+
+    return 0;
+}