Difference between revisions of "Absolute"

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{{Absolute}}
 
{{Absolute}}
  
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The absolute modifier causes a variable to be stored at the same memory location as another variable.
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<syntaxhighlight>
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// Example on x64 processor
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Uses SysUtils;
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Var
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    anInt      : Integer;
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    anotherInt : Integer absolute anInt;
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    firstByte  : Byte absolute anInt;
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begin
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    // with both Integer variables at the same memory location, a change to one is reflected
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    // in the other
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    anInt := 20;
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    WriteLn(IntToStr(anInt) + '  ' + IntToStr(anotherInt)); // Outputs: 20  20
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    // a value of 20 fits in the first byte:
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    WriteLn('firstByte: ' + IntToStr(firstByte)); // Outputs: firstByte: 20
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    anotherInt := 333;
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    WriteLn(IntToStr(anInt) + '  ' + IntToStr(anotherInt)); // Outputs: 333 333
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    // 333 is too large a value to fit in one byte
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    // 333 = 101001101 = 00000001 01001101 = 1 77
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    WriteLn('firstByte: ' + IntToStr(firstByte)); // Outputs: firstByte: 77
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end.
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</syntaxhighlight>

Revision as of 01:38, 19 September 2017

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The absolute modifier causes a variable to be stored at the same memory location as another variable.


// Example on x64 processor
Uses SysUtils;

Var
    anInt      : Integer;
    anotherInt : Integer absolute anInt;
    firstByte  : Byte absolute anInt;
 
begin
    // with both Integer variables at the same memory location, a change to one is reflected
    // in the other
    anInt := 20;
    WriteLn(IntToStr(anInt) + '  ' + IntToStr(anotherInt)); // Outputs: 20  20

    // a value of 20 fits in the first byte:
    WriteLn('firstByte: ' + IntToStr(firstByte)); // Outputs: firstByte: 20
   
    anotherInt := 333;
    WriteLn(IntToStr(anInt) + '  ' + IntToStr(anotherInt)); // Outputs: 333 333

    // 333 is too large a value to fit in one byte
    // 333 = 101001101 = 00000001 01001101 = 1 77 
    WriteLn('firstByte: ' + IntToStr(firstByte)); // Outputs: firstByte: 77
end.