I have a StringBuilder that has a string with 12,000,000 characters.
When I do a ToString(), I expect to have ~25,000,000 bytes worth of
memory, yet, I end up with ~43,000,000 bytes. That's almost double
the size. The string returned from ToString() is actually of size
StringBuilder.C apacity, NOT StringBuilder.L ength. It may have a
end-of-string character at StringBuilder.L ength, but its actual memory
size is StringBuilder.C apacity.
Does this sound right?
15  2813 
DV, I have a StringBuilder that has a string with 12,000,000 characters.
When I do a ToString(), I expect to have ~25,000,000 bytes worth of
memory, yet, I end up with ~43,000,000 bytes. That's almost double
the size. The string returned from ToString() is actually of size
StringBuilder.C apacity, NOT StringBuilder.L ength. It may have a
end-of-string character at StringBuilder.L ength, but its actual memory
size is StringBuilder.C apacity.
Capacity of a StringBuilder is how many characters can be stored in the
StringBuilder at a given time. Length is how many characters are
represented in the string that the StringBuilder represents at a given time.
The maximum value of length and capacity is 2,147,483,647.
Unicode characters can consume 2, 3 or 4 bytes. Therefore, depending on
which characters are being stored in the StringBuilder, it would be possible
to have 12,000,000 characters in the StringBuilder that translate to about
43,000,000 bytes. You will have to iterate the characters in the string
counting the bytes to see if the number of bytes can be explained by the
storage of unicode characters.
Regards,
Randy
"DV" <da*****@gmail. com> wrote in message
news:11******** **************@ j33g2000cwa.goo glegroups.com.. .
|I have a StringBuilder that has a string with 12,000,000 characters.
| When I do a ToString(), I expect to have ~25,000,000 bytes worth of
| memory, yet, I end up with ~43,000,000 bytes. That's almost double
| the size. The string returned from ToString() is actually of size
| StringBuilder.C apacity, NOT StringBuilder.L ength. It may have a
| end-of-string character at StringBuilder.L ength, but its actual memory
| size is StringBuilder.C apacity.
|
| Does this sound right?
|
No it doesn't, I really don't know where you got this value from but it's
not the size of the SB. The Capacity and Length property values are the
number of characters the SB can hold and the actual number it holds. Note
the "number of characters", not the number of bytes.
If you create a stringbuilder like this:
string s = new String('\u0306' , 12000000);
StringBuilder sb = new StringBuilder(s );
you will end with a SB buffer (a String) with a Capacity of 16777216 and a
Length of 12000000.
The length of the char[] (the string backing store) in bytes is 33554432.
Note that the string backing store is a char[], so the buffer size does not
depend encoding used as the other replier suggests, a char is fixed 2 bytes
in .NET.
Willy.
"Willy Denoyette [MVP]" <wi************ *@telenet.be> wrote in message
news:uB******** ******@tk2msftn gp13.phx.gbl...
|
| "DV" <da*****@gmail. com> wrote in message
| news:11******** **************@ j33g2000cwa.goo glegroups.com.. .
||I have a StringBuilder that has a string with 12,000,000 characters.
|| When I do a ToString(), I expect to have ~25,000,000 bytes worth of
|| memory, yet, I end up with ~43,000,000 bytes. That's almost double
|| the size. The string returned from ToString() is actually of size
|| StringBuilder.C apacity, NOT StringBuilder.L ength. It may have a
|| end-of-string character at StringBuilder.L ength, but its actual memory
|| size is StringBuilder.C apacity.
||
|| Does this sound right?
||
|
| No it doesn't, I really don't know where you got this value from but it's
| not the size of the SB. The Capacity and Length property values are the
| number of characters the SB can hold and the actual number it holds. Note
| the "number of characters", not the number of bytes.
| If you create a stringbuilder like this:
|
| string s = new String('\u0306' , 12000000);
| StringBuilder sb = new StringBuilder(s );
|
| you will end with a SB buffer (a String) with a Capacity of 16777216 and a
| Length of 12000000.
| The length of the char[] (the string backing store) in bytes is 33554432.
| Note that the string backing store is a char[], so the buffer size does
not
| depend encoding used as the other replier suggests, a char is fixed 2
bytes
| in .NET.
|
| Willy.
To add to my previous reply, if you create a SB like this:
StringBuilder sb = new StringBuilder(s , 12000000);
Your buffer will be 24000000 bytes (SB Capactity=Lengt h=12000000). The
reason for this is that now you create a SB with a predefined length, while
in the previous sample, the SB starts with a Capactity of 16 and expands by
doubling it's capacity each time it gets filled completely.
Willy.
DV <da*****@gmail. com> wrote: I have a StringBuilder that has a string with 12,000,000 characters.
When I do a ToString(), I expect to have ~25,000,000 bytes worth of
memory, yet, I end up with ~43,000,000 bytes. That's almost double
the size. The string returned from ToString() is actually of size
StringBuilder.C apacity, NOT StringBuilder.L ength. It may have a
end-of-string character at StringBuilder.L ength, but its actual memory
size is StringBuilder.C apacity.
Does this sound right?
Its size in terms of memory consumption is indeed represented by the
capacity.
--
Jon Skeet - <sk***@pobox.co m> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too
Randy A. Ynchausti <ra************ *@msn.com> wrote:
<snip> Unicode characters can consume 2, 3 or 4 bytes.
That's true in some encodings, but .NET internally uses UTF-16, which
is exactly 2 bytes per character. Surrogate pairs are treated as two
characters when it comes to things like String.Length.
--
Jon Skeet - <sk***@pobox.co m> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too
Willy Denoyette [MVP] <wi************ *@telenet.be> wrote: No it doesn't, I really don't know where you got this value from but it's
not the size of the SB. The Capacity and Length property values are the
number of characters the SB can hold and the actual number it holds. Note
the "number of characters", not the number of bytes.
If you create a stringbuilder like this:
string s = new String('\u0306' , 12000000);
StringBuilder sb = new StringBuilder(s );
you will end with a SB buffer (a String) with a Capacity of 16777216 and a
Length of 12000000.
Yes - but if you then call ToString() on that StringBuilder, you'll
find that the string only has a Length of 12000000 but takes up
2*16777216+over head bytes. In other words, StringBuilder doesn't trim
the string to its length before returning it.
--
Jon Skeet - <sk***@pobox.co m> http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too
That's why I said....
The length of the char[] (the string backing store) in bytes is 33554432.
Willy.
"Jon Skeet [C# MVP]" <sk***@pobox.co m> wrote in message
news:MP******** *************** *@msnews.micros oft.com...
| Willy Denoyette [MVP] <wi************ *@telenet.be> wrote:
| > No it doesn't, I really don't know where you got this value from but
it's
| > not the size of the SB. The Capacity and Length property values are the
| > number of characters the SB can hold and the actual number it holds.
Note
| > the "number of characters", not the number of bytes.
| > If you create a stringbuilder like this:
| >
| > string s = new String('\u0306' , 12000000);
| > StringBuilder sb = new StringBuilder(s );
| >
| > you will end with a SB buffer (a String) with a Capacity of 16777216 and
a
| > Length of 12000000.
|
| Yes - but if you then call ToString() on that StringBuilder, you'll
| find that the string only has a Length of 12000000 but takes up
| 2*16777216+over head bytes. In other words, StringBuilder doesn't trim
| the string to its length before returning it.
|
| --
| Jon Skeet - <sk***@pobox.co m>
| http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
| If replying to the group, please do not mail me too
Hit send too fast.
The String reference returned from SB.ToString() is just the same reference
to the existing String object, trimming would involve the creation of a new
string, this would increase the memory footprint and would take a
performance hit.
Willy.
"Willy Denoyette [MVP]" <wi************ *@telenet.be> wrote in message
news:OP******** ******@TK2MSFTN GP14.phx.gbl...
| That's why I said....
| The length of the char[] (the string backing store) in bytes is 33554432.
|
|
| Willy.
|
|
|
| "Jon Skeet [C# MVP]" <sk***@pobox.co m> wrote in message
| news:MP******** *************** *@msnews.micros oft.com...
|| Willy Denoyette [MVP] <wi************ *@telenet.be> wrote:
|| > No it doesn't, I really don't know where you got this value from but
| it's
|| > not the size of the SB. The Capacity and Length property values are the
|| > number of characters the SB can hold and the actual number it holds.
| Note
|| > the "number of characters", not the number of bytes.
|| > If you create a stringbuilder like this:
|| >
|| > string s = new String('\u0306' , 12000000);
|| > StringBuilder sb = new StringBuilder(s );
|| >
|| > you will end with a SB buffer (a String) with a Capacity of 16777216
and
| a
|| > Length of 12000000.
||
|| Yes - but if you then call ToString() on that StringBuilder, you'll
|| find that the string only has a Length of 12000000 but takes up
|| 2*16777216+over head bytes. In other words, StringBuilder doesn't trim
|| the string to its length before returning it.
||
|| --
|| Jon Skeet - <sk***@pobox.co m>
|| http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
|| If replying to the group, please do not mail me too
|
|
"Willy Denoyette [MVP]" <wi************ *@telenet.be> wrote in message
news:OX******** ******@TK2MSFTN GP11.phx.gbl... Hit send too fast.
The String reference returned from SB.ToString() is just the same
reference
to the existing String object, trimming would involve the creation of a
new
string, this would increase the memory footprint and would take a
performance hit.
Willy.
That's what I thought at first and then I thought about subsequent changes
to the builder - It must keep a reference to the string returned just in
case - subsequent mods must cause the copying of the string into a new
buffer but since this is uncommon in real code it's worth the optimisation.
"Willy Denoyette [MVP]" <wi************ *@telenet.be> wrote in message
news:OP******** ******@TK2MSFTN GP14.phx.gbl...
| That's why I said....
| The length of the char[] (the string backing store) in bytes is
33554432.
|
|
| Willy.
|
|
|
| "Jon Skeet [C# MVP]" <sk***@pobox.co m> wrote in message
| news:MP******** *************** *@msnews.micros oft.com...
|| Willy Denoyette [MVP] <wi************ *@telenet.be> wrote:
|| > No it doesn't, I really don't know where you got this value from but
| it's
|| > not the size of the SB. The Capacity and Length property values are
the
|| > number of characters the SB can hold and the actual number it holds.
| Note
|| > the "number of characters", not the number of bytes.
|| > If you create a stringbuilder like this:
|| >
|| > string s = new String('\u0306' , 12000000);
|| > StringBuilder sb = new StringBuilder(s );
|| >
|| > you will end with a SB buffer (a String) with a Capacity of 16777216
and
| a
|| > Length of 12000000.
||
|| Yes - but if you then call ToString() on that StringBuilder, you'll
|| find that the string only has a Length of 12000000 but takes up
|| 2*16777216+over head bytes. In other words, StringBuilder doesn't trim
|| the string to its length before returning it.
||
|| --
|| Jon Skeet - <sk***@pobox.co m>
|| http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
|| If replying to the group, please do not mail me too
|
|
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