Understanding Registry Value Data Types

by Barry Dysert
(last updated June 19, 2017)


If you ever have to get into the registry, you may be curious to know what value data types exist. Every key's value is assigned a data type. The list of valid data types includes:

  • REG_SZ. A null-terminated string
  • REG_BINARY. Binary data
  • REG_DWORD. A 32-bit number
  • REG_QWORD. A 64-bit number
  • REG_MULTI_SZ. A sequence of null-terminated strings, terminated by a null value
  • REG_EXPAND_SZ. A null-terminated string that contains unexpanded references to environment variables (like %PATH%)

Of course, if you're editing the registry you'll need to use the data type appropriate for the key you're creating. For example, there's a registry tweak you can do that will disable Windows from constantly checking for low disk space (and therefore increase by a bit the amount of resources available for other things). This is at HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies. If you click on the "Explorer" folder you can create a key named "NoLowDiskSpaceChecks". To disable Windows from doing the disk space checking, you want to put a 1 in for that key's value.

Obviously, you could use a data type of REG_BINARY, REG_DWORD, or REG_QWORD since they will all hold the value 1 with no problem. I used REG_DWORD, though, since there may come a time when the key may take on more than two values, so I wouldn't want to be limited to REG_BINARY. And REG_QWORD seems like a lot of space to simply hold a 1.

 This tip (13035) applies to Windows 7, 8, and 10.

Author Bio

Barry Dysert

Barry has been a computer professional for over 35 years, working in different positions such as technical team leader, project manager, and software developer. He is currently a software engineer with an emphasis on developing custom applications under Microsoft Windows. When not working with Windows or writing Tips, Barry is an amateur writer. His first non-fiction book is titled "A Chronological Commentary of Revelation." ...


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What is 3 + 9?

2017-09-06 04:19:20


I think the space savings would be negligible, and i wouldn't want to try it anyway. Sounds like that would be asking for trouble.

2017-09-06 01:12:48

Amaroq Starwind

Would Windows function correctly if you changed some of the default DWORD values to regular BINARY values? And would doing so use less space?

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