Maximal path and maximal file name length

[Lubomir]

Hi,

Where in .NET are definded constants for maximal file name length and
maximal file path?

Thanks,

Lubomir

[Michael Nemtsev]

Hello Lubomir,

On Windows-based platforms, paths must be less than 248 characters and file
names must be less than 260 characters.

LHi,
L>
LWhere in .NET are definded constants for maximal file name length and
Lmaximal file path?
L>
LThanks,
L>
LLubomir
L>
---
WBR,
Michael Nemtsev :: blog: http://spaces.live.com/laflour

"At times one remains faithful to a cause only because its opponents do not
cease to be insipid." (c) Friedrich Nietzsche

[Willy Denoyette [MVP]]

"Michael Nemtsev" <ne*****@msn.comwrote in message
news:17***************************@msnews.microsof t.com...
| Hello Lubomir,
|
| On Windows-based platforms, paths must be less than 248 characters and
file
| names must be less than 260 characters.
Well I know it's documented like this in the .NET IO claas API's, but
unfortunately it's completely wrong.
The maximum path length is 260 characters maximum including a terminating 0
character.
The maximum file component length is 256 characters including a terminating
0 charecter.
A file path consists of following components:
- drive component (drive letter, a colon: backslash),
- directory components, and
- a file name component

So this "c:\255 chars. filename"
and this ".\255 chars. filename"
are valid paths...

while this is not: "c:\256 chars filename" ...
filename component exceeds 256 characters(excluding the 0 character)

That means that we can say that the largest filename component length is 255
characters, that is 260 characters - the drive component lenth - 1.

Willy.

[Lubomir]

"Willy Denoyette [MVP]" wrote:

>
"Michael Nemtsev" <ne*****@msn.comwrote in message
news:17***************************@msnews.microsof t.com...
| Hello Lubomir,
|
| On Windows-based platforms, paths must be less than 248 characters and
file
| names must be less than 260 characters.
Well I know it's documented like this in the .NET IO claas API's, but
unfortunately it's completely wrong.
The maximum path length is 260 characters maximum including a terminating 0
character.
The maximum file component length is 256 characters including a terminating
0 charecter.
A file path consists of following components:
- drive component (drive letter, a colon: backslash),
- directory components, and
- a file name component

So this "c:\255 chars. filename"
and this ".\255 chars. filename"
are valid paths...

while this is not: "c:\256 chars filename" ...
filename component exceeds 256 characters(excluding the 0 character)

That means that we can say that the largest filename component length is 255
characters, that is 260 characters - the drive component lenth - 1.

Willy.

Hi,

Thanks for answers. I am familiar with those numbers from C++6.0 projects,
where I could use built-in constant MAX_PATH.

Similar aproache I would like to use in C# projects. I want to avoid using
hardcoded number 260. I prefer to use constant provided by the framework, but
I don't know where are these constant defined. Are there any at all?

Thanks for help.

Lubomir

[Michael Nemtsev]

Hello Lubomir,

There is no constant for this. If u exceed the lenght of directory name u
just get exception

L"Willy Denoyette [MVP]" wrote:
L>

>"Michael Nemtsev" <ne*****@msn.comwrote in message
news:17***************************@msnews.microso ft.com...
| Hello Lubomir,
|
| On Windows-based platforms, paths must be less than 248 characters
and
file
| names must be less than 260 characters.
Well I know it's documented like this in the .NET IO claas API's, but
unfortunately it's completely wrong.
The maximum path length is 260 characters maximum including a
terminating 0
character.
The maximum file component length is 256 characters including a
terminating
0 charecter.
A file path consists of following components:
- drive component (drive letter, a colon: backslash),
- directory components, and
- a file name component
So this "c:\255 chars. filename"
and this ".\255 chars. filename"
are valid paths...
while this is not: "c:\256 chars filename" ...
filename component exceeds 256 characters(excluding the 0 character)
That means that we can say that the largest filename component length
is 255 characters, that is 260 characters - the drive component lenth
- 1.

Willy.

LHi,
L>
LThanks for answers. I am familiar with those numbers from C++6.0
Lprojects, where I could use built-in constant MAX_PATH.
L>
LSimilar aproache I would like to use in C# projects. I want to avoid
Lusing hardcoded number 260. I prefer to use constant provided by the
Lframework, but I don't know where are these constant defined. Are
Lthere any at all?
L>
LThanks for help.
L>
LLubomir
L>
---
WBR,
Michael Nemtsev :: blog: http://spaces.live.com/laflour

"At times one remains faithful to a cause only because its opponents do not
cease to be insipid." (c) Friedrich Nietzsche

[Lubomir]

Hi Michael,

Thank you for help.
"Michael Nemtsev" wrote:

Hello Lubomir,

There is no constant for this. If u exceed the lenght of directory name u
just get exception

L"Willy Denoyette [MVP]" wrote:
L>

"Michael Nemtsev" <ne*****@msn.comwrote in message
news:17***************************@msnews.microsof t.com...
| Hello Lubomir,
|
| On Windows-based platforms, paths must be less than 248 characters
and
file
| names must be less than 260 characters.
Well I know it's documented like this in the .NET IO claas API's, but
unfortunately it's completely wrong.
The maximum path length is 260 characters maximum including a
terminating 0
character.
The maximum file component length is 256 characters including a
terminating
0 charecter.
A file path consists of following components:
- drive component (drive letter, a colon: backslash),
- directory components, and
- a file name component
So this "c:\255 chars. filename"
and this ".\255 chars. filename"
are valid paths...
while this is not: "c:\256 chars filename" ...
filename component exceeds 256 characters(excluding the 0 character)
That means that we can say that the largest filename component length
is 255 characters, that is 260 characters - the drive component lenth
- 1.

Willy.

LHi,
L>
LThanks for answers. I am familiar with those numbers from C++6.0
Lprojects, where I could use built-in constant MAX_PATH.
L>
LSimilar aproache I would like to use in C# projects. I want to avoid
Lusing hardcoded number 260. I prefer to use constant provided by the
Lframework, but I don't know where are these constant defined. Are
Lthere any at all?
L>
LThanks for help.
L>
LLubomir
L>
---
WBR,
Michael Nemtsev :: blog: http://spaces.live.com/laflour

"At times one remains faithful to a cause only because its opponents do not
cease to be insipid." (c) Friedrich Nietzsche

[Willy Denoyette [MVP]]

"Lubomir" <Lu*****@discussions.microsoft.comwrote in message
news:ED**********************************@microsof t.com...
| "Willy Denoyette [MVP]" wrote:
|
| >
| "Michael Nemtsev" <ne*****@msn.comwrote in message
| news:17***************************@msnews.microsof t.com...
| | Hello Lubomir,
| |
| | On Windows-based platforms, paths must be less than 248 characters and
| file
| | names must be less than 260 characters.
| >
| >
| Well I know it's documented like this in the .NET IO claas API's, but
| unfortunately it's completely wrong.
| The maximum path length is 260 characters maximum including a
terminating 0
| character.
| The maximum file component length is 256 characters including a
terminating
| 0 charecter.
| A file path consists of following components:
| - drive component (drive letter, a colon: backslash),
| - directory components, and
| - a file name component
| >
| So this "c:\255 chars. filename"
| and this ".\255 chars. filename"
| are valid paths...
| >
| while this is not: "c:\256 chars filename" ...
| filename component exceeds 256 characters(excluding the 0 character)
| >
| That means that we can say that the largest filename component length is
255
| characters, that is 260 characters - the drive component lenth - 1.
| >
| Willy.
|
|
| Hi,
|
| Thanks for answers. I am familiar with those numbers from C++6.0 projects,
| where I could use built-in constant MAX_PATH.
|
| Similar aproache I would like to use in C# projects. I want to avoid using
| hardcoded number 260. I prefer to use constant provided by the framework,
but
| I don't know where are these constant defined. Are there any at all?
|
| Thanks for help.
|
| Lubomir
|

There are no such constants defined in the FCL, the IO namespace classes are
wrappers arround the Win32 ANSI IO API's, so the same values apply. Anyway
when you exceed the max. path size you will get an exception thrown on you.
Note also that you can open files using the UNICODE version of the
CreateFile API through PInvoke, and use the file handle returned in a
FileStream instance, that way you can access files with a path name max. up
to 32768 bytes.

Willy.