VB6 Unsigned


Author: Dave
Date: 06.02.15 - 5:30pm



There are a couple ways that come to mind to deal with unsigned ints and longs in VB6. MS outlined a native way here

Its slightly bulky to use, and Im not sure of its overflow behavior. I want numeric overflow to be handled the same way as C natively would (wrap)

So if C already has the right behavior..use C! The below example shows just how simple it is.

I have also added 64 bit number support to the Source repo here

enum op{
	op_add = 0,
	op_sub = 1,
	op_div = 2,
	op_mul = 3,
	op_mod = 4,
	op_xor = 5,
	op_and = 6,
	op_or  = 7
};

unsigned int __stdcall ULong(unsigned int v1, unsigned int v2, int operation){

	switch(operation){
		case op_add: return v1 + v2;
		case op_sub: return v1 - v2;
		case op_div: return v1 / v2;
		case op_mul: return v1 * v2;
		case op_mod: return v1 % v2;
		case op_xor: return v1 ^ v2;
		case op_and: return v1 & v2;
		case op_or:  return v1 | v2;
	}

	return -1;

}

unsigned short __stdcall UInt(unsigned short v1, unsigned short v2, int operation){

	switch(operation){
		case op_add: return v1 + v2;
		case op_sub: return v1 - v2;
		case op_div: return v1 / v2;
		case op_mul: return v1 * v2;
		case op_mod: return v1 % v2;
		case op_xor: return v1 ^ v2;
		case op_and: return v1 & v2;
		case op_or:  return v1 | v2;
	}

	return -1;

} 


Option Explicit

Enum op
    op_add = 0
    op_sub = 1
    op_div = 2
    op_mul = 3
    op_mod = 4
    op_xor = 5
    op_and = 6
    op_or = 7
End Enum

Private Declare Function ULong Lib "utypes.dll" (ByVal v1 As Long, ByVal v2 As Long, ByVal operation As Long) As Long
Private Declare Function UInt Lib "utypes.dll" (ByVal v1 As Integer, ByVal v2 As Integer, ByVal operation As Long) As Integer

Private Sub Command1_Click()
    On Error Resume Next
    Dim a As Long
    Dim b As Integer
    
    a = 2147483647 + 1
    MsgBox Hex(2147483647) & " + 1 = " & Hex(a) & " Error: " & Err.Description
    Err.Clear
    
    a = -2147483648# - 1
    MsgBox Hex(-2147483648#) & " - 1 = " & Hex(a) & " Error: " & Err.Description
    
    b = 32767 + 1
    MsgBox Hex(32767) & " + 1 = " & Hex(b) & " Error: " & Err.Description
    Err.Clear
    
    b = -32768 - 1
    MsgBox Hex(-32768) & " - 1 = " & Hex(b) & " Error: " & Err.Description

End Sub

Private Sub Form_Load()

    testLong 2147483647, 1, op_add
    testLong -2147483648#, 1, op_sub
    
    testInt 32767, 1, op_add
    testInt -32768, 1, op_sub
    
End Sub


Sub testLong(a As Long, b As Long, opp As op) Dim ret As Long, o As Variant, msg As String o = Array("+", "-", "/", "*", "mod", "xor", "and", "or") ret = ULong(a, b, opp) msg = Hex(a) & " " & o(opp) & " " & Hex(b) & " = " & Hex(ret) List1.AddItem msg Debug.Print msg End Sub Sub testInt(a As Integer, b As Integer, opp As op) Dim ret As Integer, o As Variant, msg As String o = Array("+", "-", "/", "*", "mod", "xor", "and", "or") ret = UInt(a, b, opp) msg = Hex(a) & " " & o(opp) & " " & Hex(b) & " = " & Hex(ret) List1.AddItem msg Debug.Print msg End Sub




Output:
7FFFFFFF + 1 = 80000000
80000000 - 1 = 7FFFFFFF
7FFF + 1 = 8000
8000 - 1 = 7FFF







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