TVATCalculator 含稅金額計算類別

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VAT or Value Added Tax is a common form of taxation in the European Union (EU). VAT is added on top of the cost of a product or service and generates revenue for a government.

1. type TVATCalculator = class
   
2. private
   
3.    fVatRate: double;
   
4. public
   
5.    property VatRate : double read fVatRate;
   
6.    constructor Create (const vatValue : double) ;
   
7. 
   
8.    function Vat(const netValue : double) : double;
   
9.    function Gross(const netValue : double) : double;
   
10.    function Net(const grossValue : double) : double;
    
11.    function VatFromGross(const grossValue : double) : double;
    
12.    function NetFromVat(const vatValue : double) : double;
    
13.    function GrossFromVat(const vatValue : double) : double;
    
14. end;
    
15. 
    
16. implementation
    
17. 
    
18. constructor TVATCalculator.Create(const vatValue: double) ;
    
19. begin
    
20.    fVatRate := vatValue;
    
21. end;
    
22. 
    
23. function TVATCalculator.Gross(const netValue: double): double;
    
24. begin
    
25.    result := netValue + Vat(netValue) ;
    
26. end;
    
27. 
    
28. function TVATCalculator.GrossFromVat(const vatValue: double): double;
    
29. begin
    
30.    result := vatValue + NetFromVat(vatValue) ;
    
31. end;
    
32. 
    
33. function TVATCalculator.Net(const grossValue: double): double;
    
34. begin
    
35.    result := 100 / (100 + VatRate) * grossValue;
    
36. end;
    
37. 
    
38. function TVATCalculator.NetFromVat(const vatValue: double): double;
    
39. begin
    
40.    result := vatValue * 100 / VatRate;
    
41. end;
    
42. 
    
43. function TVATCalculator.Vat(const netValue: double): double;
    
44. begin
    
45.    result := VatRate * netValue / 100 ;
    
46. end;
    
47. 
    
48. function TVATCalculator.VatFromGross(const grossValue: double): double;
    
49. begin
    
50.    result := grossValue - Net(grossValue) ;
    
51. end;

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使用方式

1. var
   
2.    vc : TVATCalculator;
   
3.    valueIn : double;
   
4. begin
   
5.    valueIn := StrToFloat(edValue.Text);
   
6.    vc := TVATCalculator.Create(StrToFloat(edVat.Text));
   
7.    try
   
8.      edVat.Text := FormatFloat(',.00',vc.Vat(valueIn));
   
9.      edGross.Text := FormatFloat(',.00',vc.Gross(valueIn));
   
10.      edNet.Text := FormatFloat(',.00',vc.Net(valueIn));
    
11.      edVatFromGross.Text := FormatFloat(',.00',vc.VatFromGross(valueIn));
    
12.      edNetFromVat.Text := FormatFloat(',.00',vc.NetFromVat(valueIn));
    
13.      edGrossFromVat.Text := FormatFloat(',.00',vc.GrossFromVat(valueIn));
    
14.    finally
    
15.      vc.Free;
    
16.    end;
    
17. end;

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執行畫面

2010-9-9 09:58 上傳

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用  5% 計算 100 的結果

2010-9-9 09:58 上傳

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資料來源 http://delphi.about.com/od/delph ... -vat-calculator.htm