64-bit Windows Data Types Compared to 32-bit Windows Data Types

Go Up to 64-bit Cross-Platform Application Development for Windows

The following tables summarize the differences and similarities between 64-bit OS data types and 32-bit OS data types.

Delphi 32-bit and 64-bit Windows built-in type sizes

Integral types

On Win64, NativeInt is twice the size of the Win32 NativeInt, and NativeUInt is twice the size of the Win32 NativeUInt.

Signed Integer	Unsigned Integer	Delphi/32	Delphi/64
ShortInt	Byte	1 byte
SmallInt	Word	2 bytes
LongInt	LongWord	4 bytes
FixedInt	FixedUInt	4 bytes
Integer	Cardinal	4 bytes
Int64	UInt64	8 bytes
NativeInt	NativeUInt	4 bytes	8 bytes

Pointer types

On 64-bit Windows, all pointer types are 8 bytes, twice the size on 32-bit Windows.

Pointer types	Delphi/32	Delphi/64
Pointer	4 bytes	8 bytes
string
class instance
class reference
interface
AnsiString
WideString
UnicodeString
procedure pointer
dynamic array
PAnsiChar
PWideChar
PChar

Procedure of object

On 64-bit Windows, the alignment for a procedure of object is 16 bytes, twice the size on 32-bit Windows.

Procedure of object	Delphi/32	Delphi/64	Comments
Size	8 bytes	16 bytes
Alignment	8 bytes	16 bytes	Known as closure type

Floating-point types (including the Extended data type)

The Extended type has 2 bytes' worth less precision on 64-bit Windows than on 32-bit Windows (8 bytes vs 10 bytes)..

For more information, see The Extended Data Type Is 2 Bytes Smaller on 64-bit Windows Systems.

Floating point types	Delphi/32	Delphi/64	Comments
Single	4 bytes
Double	8 bytes
Real	8 bytes
Extended	10 bytes	8 bytes	TExtended80Rec has 10 bytes on Win64
Real48	6 bytes
Comp	8 bytes
Currency	8 bytes

Other types

On Win64, file size has increased.

Other types	Delphi/32	Delphi/64	Comments
Boolean	1 byte
ByteBool	1 byte
WordBool	2 bytes
LongBool	4 bytes
AnsiChar	1 byte
WideChar	2 bytes
Char	2 bytes
ShortString	256 bytes
string[N]	N+1 bytes
Variant / OleVariant	16 bytes		24 bytes
file	592 bytes	616 bytes
Text / TextFile	730 bytes	754 bytes	720 bytes in XE release

Constants

Constants	Delphi/32	Delphi/64
MaxInt	$7fffffff
MaxLongInt	$7fffffff

C++Builder 32-bit and 64-bit Windows built-in type sizes

The following tables summarize the differences and similarities between 64-bit OS data types and 32-bit OS data types in C++Builder.

Note: In order to use members of the System unit (such as System::Byte), you need to #include <System.hpp>.

Integral types

On Win64, System::NativeInt/ssize_t is twice the size of the Win32 System::NativeInt/ssize_t.
Likewise, System::NativeUInt/ssize_t is twice the size of the Win32 System::NativeUInt/size_t.

Signed Integer	Unsigned Integer	C++/32	C++/64	Comments
signed char	System::Byte, unsigned char	1 byte
System::Smallint, short	System::Word, unsigned short	2 bytes
System::LongInt, signed long	System::LongWord, unsigned	4 bytes
System::Integer, int	System::Cardinal, unsigned int	4 bytes
System::Int64, unsigned __int64, long long	System::UInt64, unsigned __int64, unsigned long long	8 bytes
System::NativeInt, ssize_t	System::NativeUInt, size_t	4 bytes	8 bytes

Pointer types

On 64-bit Windows, all pointer types are 8 bytes, twice the size on 32-bit Windows.

Pointer types	C++/32	C++/64
System::Pointer, void*	4 bytes	8 bytes
System::String, System::UnicodeString
System::TObject
System::TClass
System::IInterface, System::DelphiInterface
System::AnsiString, System::AnsiStringT<code-page>
System::WideString
System::UnicodeString
System::DynamicArray
System::PAnsiChar
System::PWideChar
System::PChar

__closure

On 64-bit Windows, the alignment for a __closure is 16 bytes, twice the size on 32-bit Windows.

__closure

8 bytes

16 bytes

Floating-point types (including the Extended data type)

The Extended type has 2 bytes' worth less precision on 64-bit Windows.

For more information, see The Extended Data Type Is 2 Bytes Smaller on 64-bit Windows Systems.

Floating point types	C++/32	C++/64	Comments
System::Single, float	4 bytes
System::Double, double	8 bytes
System::Extended, long double	10 bytes	8 bytes	TExtended80Rec has 10 bytes on Win64
Real48	Not Supported
System::Comp	8 bytes
System::Currency	8 bytes

Other types

On Win64, file size has increased.

Other types	C++/32	C++/64	Comments
System::Boolean, bool	1 byte
System::ByteBool, unsigned char	1 byte
System::WordBool, unsigned short	2 bytes
System::LongBool, unsigned int	4 bytes
System::AnsiChar, char	1 byte
System::WideChar, wchar_t	2 bytes
System::Char, wchar_t (Windows), char16_t (OSX)	2 bytes
System::ShortString	256 bytes
Variant / OleVariant	16 bytes		24 bytes

Constants

Constants	C++/32	C++/64
MaxInt	$7fffffff
MaxLongInt	$7fffffff

See Also

• Simple Types (Delphi)
• Delphi to C++ types mapping
• The Fundamental Types (C++)
• The Extended Data Type Is 2 Bytes Smaller on 64-bit Windows Systems