System.TSingleRec
Delphi
TSingleRec = packed record
private
aSingle: Single;
function InternalGetBytes(Index: Cardinal): UInt8; inline;
function InternalGetWords(Index: Cardinal): UInt16; inline;
procedure InternalSetBytes(Index: Cardinal; const Value: UInt8); inline;
procedure InternalSetWords(Index: Cardinal; const Value: UInt16); inline;
function GetBytes(Index: Cardinal): UInt8; inline;
function GetWords(Index: Cardinal): UInt16; inline;
procedure SetBytes(Index: Cardinal; const Value: UInt8); inline;
procedure SetWords(Index: Cardinal; const Value: UInt16); inline;
function GetExp: UInt64; inline;
function GetFrac: UInt64; inline;
function GetSign: Boolean; inline;
procedure SetExp(NewExp: UInt64);
procedure SetFrac(NewFrac: UInt64);
procedure SetSign(NewSign: Boolean);
public
function Exponent: Integer;
function Fraction: Extended;
function Mantissa: UInt64;
property Sign: Boolean read GetSign write SetSign;
property Exp: UInt64 read GetExp write SetExp;
property Frac: UInt64 read GetFrac write SetFrac;
function SpecialType: TFloatSpecial;
procedure BuildUp(const SignFlag: Boolean; const Mantissa: UInt64; const Exponent: Integer);
class operator Explicit(a: Extended): TSingleRec; inline;
class operator Explicit(a: TSingleRec): Extended; inline;
property Bytes[Index: Cardinal]: UInt8 read GetBytes write SetBytes; // 0..3
property Words[Index: Cardinal]: UInt16 read GetWords write SetWords; // 0..1
end deprecated 'Use TSingleHelper';
C++
struct DECLSPEC_DRECORD TSingleRec
{
private:
float aSingle;
Byte __fastcall InternalGetBytes(unsigned Index);
Word __fastcall InternalGetWords(unsigned Index);
void __fastcall InternalSetBytes(unsigned Index, const Byte Value);
void __fastcall InternalSetWords(unsigned Index, const Word Value);
Byte __fastcall GetBytes(unsigned Index);
Word __fastcall GetWords(unsigned Index);
void __fastcall SetBytes(unsigned Index, const Byte Value);
void __fastcall SetWords(unsigned Index, const Word Value);
unsigned __int64 __fastcall GetExp(void);
unsigned __int64 __fastcall GetFrac(void);
bool __fastcall GetSign(void);
void __fastcall SetExp(unsigned __int64 NewExp);
void __fastcall SetFrac(unsigned __int64 NewFrac);
void __fastcall SetSign(bool NewSign);
public:
int __fastcall Exponent(void);
Extended __fastcall Fraction(void);
unsigned __int64 __fastcall Mantissa(void);
__property bool Sign = {read=GetSign, write=SetSign};
__property unsigned __int64 Exp = {read=GetExp, write=SetExp};
__property unsigned __int64 Frac = {read=GetFrac, write=SetFrac};
TFloatSpecial __fastcall SpecialType(void);
void __fastcall BuildUp(const bool SignFlag, const unsigned __int64 Mantissa, const int Exponent);
static TSingleRec __fastcall _op_Explicit(Extended a);
__property Byte Bytes[unsigned Index] = {read=GetBytes, write=SetBytes};
__property Word Words[unsigned Index] = {read=GetWords, write=SetWords};
};
Propriétés
| Type | Visibilité | Source | Unité | Parent |
|---|---|---|---|---|
record struct |
public | System.pas System.hpp |
System | System |
Description
Avertissement : TSingleRec est obsolète. Veuillez utiliser SysUtils.TSingleHelper.
TSingleRec peut effectuer des opérations de bas niveau sur une valeur à virgule flottante en simple précision.
Depuis XE3, les propriétés TSingleRec.Bytes et TSingleRec.Words sont des propriétés tableau. Les opérateurs System.High et System.Low ne s'appliquent pas aux propriétés tableau. Vous pouvez utiliser à la place System.SizeOf, comme illustré dans l'exemple suivant.
Exemple
Dans la version XE2 de cet exemple, System.High et System.Low étaient utilisés pour l'itération octet par octet au sein du TSingleRec, comme suit :
for I := High(F.Bytes) downto Low(F.Bytes) do
Dans l'exemple XE3, System.SizeOf est utilisé au lieu de High et de Low :
var
F: TSingleRec;
I: Integer;
begin
F := TSingleRec(-0.5);
// display the hexadecimal representation of the single precision floating-point value
// leftmost bytes are the most significant
for I := sizeof(F) - 1 downto 0 do
Write(IntToHex(F.Bytes[I], 2) + ' ');
Writeln;
// display the value contained in the TSingleRec record
Writeln(FloatToStr(Single(F)));
// ...
Sortie console :
BF 00 00 00 -0.5