Difference between revisions of "Absolute"
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{{Absolute}} | {{Absolute}} | ||
− | + | The absolute modifier causes a variable to be stored at the same memory location as another variable. | |
+ | |||
+ | |||
+ | <syntaxhighlight> | ||
+ | // 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. | ||
+ | </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.