What is the bit size of long on 64-bit Windows

Question

Not to long ago  someone told me that long are not 64 bits on 64 bit machines and I should always use int  This did not make sense to me  I have seen docs  such as the one on Apple s official site  say that long are indeed 64 bits when compiling for a 64-bit CPU  I looked up what it was on 64-bit Windows and found         Windows  long and int remain 32-bit in length  and special new data types   are defined for 64-bit integers        from http   www intel com cd ids developer asmo-na eng 197664 htm page 2   What should I use  Should I define something like uw  sw   un signed width  as a long if not on Windows  and otherwise do a check on the target CPU bitsize

User · Answer

This article on MSDN references a number of type aliases (available on Windows) that are a bit more explicit with respect to their width:

http://msdn.microsoft.com/en-us/library/aa505945.aspx

For instance, although you can use ULONGLONG to reference a 64-bit unsigned integral value, you can also use UINT64. (The same goes for ULONG and UINT32.) Perhaps these will be a bit clearer?

User · Answer

It is not clear if the question is about the Microsoft C   compiler or the Windows API  However  there is no  c    tag so I assume it is about the Windows API  Some of the answers have suffered from link rot so I am providing yet another link that can rot     For information about Windows API types like INT  LONG etc  there is a page on MSDN   Windows Data Types  The information is also available in various Windows header files like WinDef h  I have listed a few relevant types here    Type                          S U   x86      x64 ---------------------------- ----- -------- ------- BYTE  BOOLEAN                 U     8 bit    8 bit ---------------------------- ----- -------- ------- SHORT                         S     16 bit   16 bit USHORT  WORD                  U     16 bit   16 bit ---------------------------- ----- -------- ------- INT  LONG                     S     32 bit   32 bit UINT  ULONG  DWORD            U     32 bit   32 bit ---------------------------- ----- -------- ------- INT PTR  LONG PTR  LPARAM     S     32 bit   64 bit UINT PTR  ULONG PTR  WPARAM   U     32 bit   64 bit ---------------------------- ----- -------- ------- LONGLONG                      S     64 bit   64 bit ULONGLONG  QWORD              U     64 bit   64 bit   The column  S U  denotes signed unsigned

User · Answer

In the Unix world  there were a few possible arrangements for the sizes of integers and pointers for 64-bit platforms   The two mostly widely used were ILP64  actually  only a very few examples of this  Cray was one such  and LP64  for almost everything else    The acronynms come from  int  long  pointers are 64-bit  and  long  pointers are 64-bit    Type           ILP64   LP64   LLP64 char              8      8       8 short            16     16      16 int              64     32      32 long             64     64      32 long long        64     64      64 pointer          64     64      64   The ILP64 system was abandoned in favour of LP64  that is  almost all later entrants used LP64  based on the recommendations of the Aspen group  only systems with a long heritage of 64-bit operation use a different scheme   All modern 64-bit Unix systems use LP64   MacOS X and Linux are both modern 64-bit systems   Microsoft uses a different scheme for transitioning to 64-bit  LLP64   long long  pointers are 64-bit     This has the merit of meaning that 32-bit software can be recompiled without change   It has the demerit of being different from what everyone else does  and also requires code to be revised to exploit 64-bit capacities   There always was revision necessary  it was just a different set of revisions from the ones needed on Unix platforms   If you design your software around platform-neutral integer type names  probably using the C99  lt inttypes h gt  header  which  when the types are available on the platform  provides  in signed  listed  and unsigned  not listed  prefix with  u      int8 t - 8-bit integers int16 t - 16-bit integers int32 t - 32-bit integers int64 t - 64-bit integers uintptr t - unsigned integers big enough to hold pointers intmax t - biggest size of integer on the platform  might be larger than int64 t    You can then code your application using these types where it matters  and being very careful with system types  which might be different    There is an intptr t type - a signed integer type for holding pointers  you should plan on not using it  or only using it as the result of a subtraction of two uintptr t values  ptrdiff t    But  as the question points out  in disbelief   there are different systems for the sizes of the integer data types on 64-bit machines   Get used to it  the world isn t going to change

User · Answer

The easiest way to get to know it for your compiler platform    include  lt iostream gt   int main       std  cout  lt  lt  sizeof long  8  lt  lt  std  endl      Themultiplication by 8 is to get bits from bytes   When you need a particular size  it is often easiest to use one of the predefined types of a library  If that is undesirable  you can do what often happens with autoconf software and have the configuration system determine the right type for the needed size

User · Answer

Microsoft has also defined UINT PTR and INT PTR for integers that are the same size as a pointer   Here is a list of Microsoft specific types - it s part of their driver reference  but I believe it s valid for general programming as well

User · Answer

This article on MSDN references a number of type aliases (available on Windows) that are a bit more explicit with respect to their width:

http://msdn.microsoft.com/en-us/library/aa505945.aspx

For instance, although you can use ULONGLONG to reference a 64-bit unsigned integral value, you can also use UINT64. (The same goes for ULONG and UINT32.) Perhaps these will be a bit clearer?

User · Answer

If you need to use integers of certain length  you probably should use some platform independent headers to help you  Boost is a good place to look at

User · Answer

Microsoft has also defined UINT PTR and INT PTR for integers that are the same size as a pointer   Here is a list of Microsoft specific types - it s part of their driver reference  but I believe it s valid for general programming as well

User · Answer

The size in bits of long on Windows platforms is 32 bits  4 bytes    You can check this using sizeof long

User · Answer

The easiest way to get to know it for your compiler platform    include  lt iostream gt   int main       std  cout  lt  lt  sizeof long  8  lt  lt  std  endl      Themultiplication by 8 is to get bits from bytes   When you need a particular size  it is often easiest to use one of the predefined types of a library  If that is undesirable  you can do what often happens with autoconf software and have the configuration system determine the right type for the needed size

User · Answer

The easiest way to get to know it for your compiler platform    include  lt iostream gt   int main       std  cout  lt  lt  sizeof long  8  lt  lt  std  endl      Themultiplication by 8 is to get bits from bytes   When you need a particular size  it is often easiest to use one of the predefined types of a library  If that is undesirable  you can do what often happens with autoconf software and have the configuration system determine the right type for the needed size

User · Answer

If you need to use integers of certain length  you probably should use some platform independent headers to help you  Boost is a good place to look at

User · Answer

In the Unix world  there were a few possible arrangements for the sizes of integers and pointers for 64-bit platforms   The two mostly widely used were ILP64  actually  only a very few examples of this  Cray was one such  and LP64  for almost everything else    The acronynms come from  int  long  pointers are 64-bit  and  long  pointers are 64-bit    Type           ILP64   LP64   LLP64 char              8      8       8 short            16     16      16 int              64     32      32 long             64     64      32 long long        64     64      64 pointer          64     64      64   The ILP64 system was abandoned in favour of LP64  that is  almost all later entrants used LP64  based on the recommendations of the Aspen group  only systems with a long heritage of 64-bit operation use a different scheme   All modern 64-bit Unix systems use LP64   MacOS X and Linux are both modern 64-bit systems   Microsoft uses a different scheme for transitioning to 64-bit  LLP64   long long  pointers are 64-bit     This has the merit of meaning that 32-bit software can be recompiled without change   It has the demerit of being different from what everyone else does  and also requires code to be revised to exploit 64-bit capacities   There always was revision necessary  it was just a different set of revisions from the ones needed on Unix platforms   If you design your software around platform-neutral integer type names  probably using the C99  lt inttypes h gt  header  which  when the types are available on the platform  provides  in signed  listed  and unsigned  not listed  prefix with  u      int8 t - 8-bit integers int16 t - 16-bit integers int32 t - 32-bit integers int64 t - 64-bit integers uintptr t - unsigned integers big enough to hold pointers intmax t - biggest size of integer on the platform  might be larger than int64 t    You can then code your application using these types where it matters  and being very careful with system types  which might be different    There is an intptr t type - a signed integer type for holding pointers  you should plan on not using it  or only using it as the result of a subtraction of two uintptr t values  ptrdiff t    But  as the question points out  in disbelief   there are different systems for the sizes of the integer data types on 64-bit machines   Get used to it  the world isn t going to change

User · Answer

This article on MSDN references a number of type aliases (available on Windows) that are a bit more explicit with respect to their width:

http://msdn.microsoft.com/en-us/library/aa505945.aspx

For instance, although you can use ULONGLONG to reference a 64-bit unsigned integral value, you can also use UINT64. (The same goes for ULONG and UINT32.) Perhaps these will be a bit clearer?

User · Answer

This article on MSDN references a number of type aliases (available on Windows) that are a bit more explicit with respect to their width:

http://msdn.microsoft.com/en-us/library/aa505945.aspx

For instance, although you can use ULONGLONG to reference a 64-bit unsigned integral value, you can also use UINT64. (The same goes for ULONG and UINT32.) Perhaps these will be a bit clearer?

User · Answer

If you need to use integers of certain length  you probably should use some platform independent headers to help you  Boost is a good place to look at

User · Answer

The size in bits of long on Windows platforms is 32 bits  4 bytes    You can check this using sizeof long

User · Answer

It is not clear if the question is about the Microsoft C   compiler or the Windows API  However  there is no  c    tag so I assume it is about the Windows API  Some of the answers have suffered from link rot so I am providing yet another link that can rot     For information about Windows API types like INT  LONG etc  there is a page on MSDN   Windows Data Types  The information is also available in various Windows header files like WinDef h  I have listed a few relevant types here    Type                          S U   x86      x64 ---------------------------- ----- -------- ------- BYTE  BOOLEAN                 U     8 bit    8 bit ---------------------------- ----- -------- ------- SHORT                         S     16 bit   16 bit USHORT  WORD                  U     16 bit   16 bit ---------------------------- ----- -------- ------- INT  LONG                     S     32 bit   32 bit UINT  ULONG  DWORD            U     32 bit   32 bit ---------------------------- ----- -------- ------- INT PTR  LONG PTR  LPARAM     S     32 bit   64 bit UINT PTR  ULONG PTR  WPARAM   U     32 bit   64 bit ---------------------------- ----- -------- ------- LONGLONG                      S     64 bit   64 bit ULONGLONG  QWORD              U     64 bit   64 bit   The column  S U  denotes signed unsigned

User · Answer

The easiest way to get to know it for your compiler platform    include  lt iostream gt   int main       std  cout  lt  lt  sizeof long  8  lt  lt  std  endl      Themultiplication by 8 is to get bits from bytes   When you need a particular size  it is often easiest to use one of the predefined types of a library  If that is undesirable  you can do what often happens with autoconf software and have the configuration system determine the right type for the needed size

User · Answer

If you need to use integers of certain length  you probably should use some platform independent headers to help you  Boost is a good place to look at

User · Answer

In the Unix world  there were a few possible arrangements for the sizes of integers and pointers for 64-bit platforms   The two mostly widely used were ILP64  actually  only a very few examples of this  Cray was one such  and LP64  for almost everything else    The acronynms come from  int  long  pointers are 64-bit  and  long  pointers are 64-bit    Type           ILP64   LP64   LLP64 char              8      8       8 short            16     16      16 int              64     32      32 long             64     64      32 long long        64     64      64 pointer          64     64      64   The ILP64 system was abandoned in favour of LP64  that is  almost all later entrants used LP64  based on the recommendations of the Aspen group  only systems with a long heritage of 64-bit operation use a different scheme   All modern 64-bit Unix systems use LP64   MacOS X and Linux are both modern 64-bit systems   Microsoft uses a different scheme for transitioning to 64-bit  LLP64   long long  pointers are 64-bit     This has the merit of meaning that 32-bit software can be recompiled without change   It has the demerit of being different from what everyone else does  and also requires code to be revised to exploit 64-bit capacities   There always was revision necessary  it was just a different set of revisions from the ones needed on Unix platforms   If you design your software around platform-neutral integer type names  probably using the C99  lt inttypes h gt  header  which  when the types are available on the platform  provides  in signed  listed  and unsigned  not listed  prefix with  u      int8 t - 8-bit integers int16 t - 16-bit integers int32 t - 32-bit integers int64 t - 64-bit integers uintptr t - unsigned integers big enough to hold pointers intmax t - biggest size of integer on the platform  might be larger than int64 t    You can then code your application using these types where it matters  and being very careful with system types  which might be different    There is an intptr t type - a signed integer type for holding pointers  you should plan on not using it  or only using it as the result of a subtraction of two uintptr t values  ptrdiff t    But  as the question points out  in disbelief   there are different systems for the sizes of the integer data types on 64-bit machines   Get used to it  the world isn t going to change

User · Answer

Microsoft has also defined UINT PTR and INT PTR for integers that are the same size as a pointer   Here is a list of Microsoft specific types - it s part of their driver reference  but I believe it s valid for general programming as well

User · Answer

In the Unix world  there were a few possible arrangements for the sizes of integers and pointers for 64-bit platforms   The two mostly widely used were ILP64  actually  only a very few examples of this  Cray was one such  and LP64  for almost everything else    The acronynms come from  int  long  pointers are 64-bit  and  long  pointers are 64-bit    Type           ILP64   LP64   LLP64 char              8      8       8 short            16     16      16 int              64     32      32 long             64     64      32 long long        64     64      64 pointer          64     64      64   The ILP64 system was abandoned in favour of LP64  that is  almost all later entrants used LP64  based on the recommendations of the Aspen group  only systems with a long heritage of 64-bit operation use a different scheme   All modern 64-bit Unix systems use LP64   MacOS X and Linux are both modern 64-bit systems   Microsoft uses a different scheme for transitioning to 64-bit  LLP64   long long  pointers are 64-bit     This has the merit of meaning that 32-bit software can be recompiled without change   It has the demerit of being different from what everyone else does  and also requires code to be revised to exploit 64-bit capacities   There always was revision necessary  it was just a different set of revisions from the ones needed on Unix platforms   If you design your software around platform-neutral integer type names  probably using the C99  lt inttypes h gt  header  which  when the types are available on the platform  provides  in signed  listed  and unsigned  not listed  prefix with  u      int8 t - 8-bit integers int16 t - 16-bit integers int32 t - 32-bit integers int64 t - 64-bit integers uintptr t - unsigned integers big enough to hold pointers intmax t - biggest size of integer on the platform  might be larger than int64 t    You can then code your application using these types where it matters  and being very careful with system types  which might be different    There is an intptr t type - a signed integer type for holding pointers  you should plan on not using it  or only using it as the result of a subtraction of two uintptr t values  ptrdiff t    But  as the question points out  in disbelief   there are different systems for the sizes of the integer data types on 64-bit machines   Get used to it  the world isn t going to change

User · Answer

Microsoft has also defined UINT PTR and INT PTR for integers that are the same size as a pointer   Here is a list of Microsoft specific types - it s part of their driver reference  but I believe it s valid for general programming as well

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