旧 Pascal 代码中十六进制数之和的条件

Question

我有一个非常古老的 Pascal 程序。单元顶部是一组常量，如下所示：

feature1 = $01; 
feature2 = $02; 
feature3 = $04;
feature4 = $08; 
feature5 = $10;

数据库中有一列代表属性，并且有上述特征组合的总和。我认为它可能非常有用，即使在今天它也可以让我们避免复杂的情况 条件块，但我想阅读更多相关内容并查看更多此类代码的解释良好的示例。因此，如果您之前看到类似的内容，我将不胜感激一些文章和练习的链接，因为我什至不知道我必须在 Google 中搜索什么。

Answer 1

这是一个使用 Free Pascal 中常量的示例

Program HexConstants;

Const
    (* In Pascal a hexadecimal numeric literal is indicated by prefixing a numeric literal with a $ *)
    feature1 = $01;
    feature2 = $02;
    feature3 = $04;
    feature4 = $08;
    feature5 = $10;

Var
    features : integer;

procedure PrintFeatureDecimalValues();
Var
    feature : integer;
begin
    feature := feature1;
    Writeln(' feature1 = ', feature);
    features := feature2;
    Writeln(' feature2 = ', feature2);
    features := feature3;
    Writeln(' feature3 = ', feature3);
    features := feature4;
    Writeln(' feature4 = ', feature4);
    features := feature5;
    Writeln(' feature5 = ', feature5);
    Writeln('__________________________________');
end;

procedure ShowFeaturesThatAreSet(features : integer);
begin
    if features = 0 then
        Writeln('No features are set');
    if features and feature1 = feature1 then
        Writeln('Feature 1 is set');
    if features and feature2 = feature2 then
        Writeln('Feature 2 is set');
    if features and feature3 = feature3 then
        Writeln('Feature 3 is set');
    if features and feature4 = feature4 then
        Writeln('Feature 4 is set');
    if features and feature5 = feature5 then
        Writeln('Feature 5 is set');
    Writeln('__________________________________');
end;

Begin
    PrintFeatureDecimalValues;
    features := feature1 + feature3;
    ShowFeaturesThatAreSet(features);
    features := feature4 + feature5;
    ShowFeaturesThatAreSet(features);
    features := 0;
    ShowFeaturesThatAreSet(features);
    features := feature1 + feature2 + feature3 + feature4 + feature5;
    ShowFeaturesThatAreSet(features);

End.