Task: Set
C: #include <stdio.h>

typedef unsigned int set_t; 

void show_set(set_t x, const char *name)
{
	int i;
	printf("%s is:", name);
	for (i = 0; (1U << i) <= x; i++)
		if (x & (1U << i))
			printf(" %d", i);
	putchar('\n');
}

int main(void)
{
	int i;
	set_t a, b, c;
	
	a = 0; 
	for (i = 0; i < 10; i += 3) 
		a |= (1U << i);
	show_set(a, "a");

	for (i = 0; i < 5; i++)
		printf("\t%d%s in set a\n", i, (a & (1U << i)) ? "":" not");

	b = a;
	b |= (1U << 5); b |= (1U << 10); 
	b &= ~(1U << 0);	
	show_set(b, "b");

	show_set(a | b, "union(a, b)");
	show_set(c = a & b, "c = common(a, b)");
	show_set(a & ~b, "a - b"); 
	show_set(b & ~a, "b - a");
	printf("b is%s a subset of a\n", !(b & ~a) ? "" : " not");
	printf("c is%s a subset of a\n", !(c & ~a) ? "" : " not");

	printf("union(a, b) - common(a, b) %s union(a - b, b - a)\n",
		((a | b) & ~(a & b)) == ((a & ~b) | (b & ~a))
			? "equals" : "does not equal");

	return 0;
}

VB: 





Private Function createSet(t As Variant) As Collection
    Dim x As New Collection
    For Each elem In t
        x.Add elem, elem
    Next elem
    Set createSet = x
End Function
Private Function isElement(s As Variant, x As Collection) As Boolean
    Dim errno As Integer, t As Variant
    On Error GoTo err
    t = x(s)
    isElement = True
    Exit Function
err:
    isElement = False
End Function
Private Function setUnion(A As Collection, B As Collection) As Collection
    Dim x As New Collection
    For Each elem In A
        x.Add elem, elem
    Next elem
    For Each elem In B
        On Error Resume Next 
        x.Add elem, elem
    Next elem
    Set setUnion = x
End Function
Private Function intersection(A As Collection, B As Collection) As Collection
    Dim x As New Collection
    For Each elem In A
        If isElement(elem, B) Then x.Add elem, elem
    Next elem
    For Each elem In B
        If isElement(elem, A) Then
            On Error Resume Next
            x.Add elem, elem
        End If
    Next elem
    Set intersection = x
End Function
Private Function difference(A As Collection, B As Collection) As Collection
    Dim x As New Collection
    For Each elem In A
        If Not isElement(elem, B) Then x.Add elem, elem
    Next elem
    Set difference = x
End Function
Private Function subset(A As Collection, B As Collection) As Boolean
    Dim flag As Boolean
    flag = True
    For Each elem In A
        If Not isElement(elem, B) Then
            flag = False
            Exit For
        End If
    Next elem
    subset = flag
End Function
Private Function equality(A As Collection, B As Collection) As Boolean
    Dim flag As Boolean
    flag = True
    If A.Count = B.Count Then
        For Each elem In A
            If Not isElement(elem, B) Then
                flag = False
                Exit For
            End If
        Next elem
    Else
        flag = False
    End If
    equality = flag
End Function
Private Function properSubset(A As Collection, B As Collection) As Boolean
    Dim flag As Boolean
    flag = True
    If A.Count < B.Count Then
        For Each elem In A
            If Not isElement(elem, B) Then
                flag = False
                Exit For
            End If
        Next elem
    Else
        flag = False
    End If
    properSubset = flag
End Function
Public Sub main()
    
    Dim s As Variant
    Dim A As Collection, B As Collection, C As Collection
    s = [{"Apple","Banana","Pear","Pineapple"}]
    Set A = createSet(s) 
    
    Debug.Print isElement("Apple", A) 
    Debug.Print isElement("Fruit", A) 
    
    s = [{"Fruit","Banana","Pear","Orange"}]
    Set B = createSet(s)
    Set C = setUnion(A, B)
    
    Set C = intersection(A, B)
    
    Set C = difference(A, B)
    
    Debug.Print subset(A, B)
    
    Debug.Print equality(A, B)
    
    Debug.Print properSubset(A, B)
    
    A.Remove "Apple"
    
    A.Remove 1
    
    A.Add "10", "10"
End Sub