string.Join throws OutOfMemory Exception

Question

I have a list of strings and I want to join them with " "(space) between them, so I use the string.Join method:

foreach (var line in lines)
{        
    var strings = lines.Where(l => l.Code == line.Code).Select(l => l.Data);
    var original = string.Join(" ", strings);        
}

Data looks something like this: "123456789, 987654321, 32132, 7873892 ..."

But I get an OutOfMemoryException. Why? each string is approximatly 100-150 characters and there are 5-10 strings in the list.

Is there a better way then the string.Join?

What else is the program doing? This might just be the thing that pushes you over the edge. — unholysampler, Dec 06 '11 at 21:17
There must be something else going on (loop, recursion, etc). We need to see the full code or the exception stack trace. — James Michael Hare, Dec 06 '11 at 21:17
I know this is a stupid question, but original isn't a reference to one of the strings in `strings`, is it? — Jonathan Rich, Dec 06 '11 at 21:17
my guess: this is in the middle of a `for` / `foreach` / `do` loop — Marc Gravell, Dec 06 '11 at 21:18
@Oded, sorry it was typing error, I deleted the +. again,sorry — gdoron, Dec 06 '11 at 21:19
@JonathanRich - Can't be as `original` is declared on that line. — Oded, Dec 06 '11 at 21:19
@Oded It was originally `original += ...`, the OP must have updated his code sample. — Jonathan Rich, Dec 06 '11 at 21:20
@JonathanRich - it was originally `var original +=` which looked very strange. But as Christopher commented, we need more code. — Oded, Dec 06 '11 at 21:22
is `strings` a standard array or list or is it a more complicated type from an external library or one of your own? Perhaps the enumerator is doing something silly. — Steve Rukuts, Dec 06 '11 at 21:22
@Oded 20 lines. each data is 100-150 chars, do you see recursion here? — gdoron, Dec 06 '11 at 21:28
This is doing lots of extra work. If every line has a code of 1, then you are doing this join operation n times and each loop does a where that collects every line. Even though each iteration produces the exact same result. — unholysampler, Dec 06 '11 at 21:28
What is the type of `lines`? Could iterating over it be the real source of the issue? — jason, Dec 06 '11 at 21:29
@gdoron: Support your assertion with facts. There is obviously something mysterious going on here. — jason, Dec 06 '11 at 21:31
@gdoron How does the line class (with the `Code` and `Data` properties) look? — Magnus, Dec 06 '11 at 21:39

score 4 · Accepted Answer · answered Dec 06 '11 at 21:31

4

Try this (and let us know if you get the same error):

lines.GroupBy(l => l.Code).Select(l => string.Join(" ", l.Select (x => x.Data)));

answered Dec 06 '11 at 21:31

Magnus

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score 2 · Answer 2 · edited Dec 06 '11 at 21:36

2

foreach (var line in lines.GroupBy(p=>p.Code))
{        
    var original = string.Join(" ", line.Select(p=>p.Data));        
}

edited Dec 06 '11 at 21:36

Magnus

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answered Dec 06 '11 at 21:28

Reza ArabQaeni

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score -1 · Answer 3 · answered Dec 06 '11 at 21:26

-1

The StringBuild() class can join strings and isn't immutable.

Here's an MSDN article talking about immutable string vs how StringBuilder works. http://msdn.microsoft.com/en-us/library/2839d5h5(v=vs.71).aspx

answered Dec 06 '11 at 21:26

user1231231412

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I'm not the downvoter, but I'm not curious as to what this has to do with gdoron's question. – Steve Rukuts Dec 06 '11 at 21:30
@Raskolnikov He asked "Is there a better way then the string.Join?" My answer was SringBuilder. The OutOfMemory could be caused by a million unrelated things. My understanding is that StringBuilder is the suggested method by MS to concatenate a bunch of strings. I don't think my suggestion was completely off-topic?! – user1231231412 Dec 06 '11 at 21:39
@JonC: (I'm not the downvoter either) `String.Join()` is actually more efficient than `StringBuilder` because it can determine the lengths before-hand and build the exact sized buffer. – James Michael Hare Dec 06 '11 at 21:42
@JonC `String.Join` can actually be faster than `StringBuilder` see:http://stackoverflow.com/questions/585860/string-join-vs-stringbuilder-which-is-faster – Magnus Dec 06 '11 at 21:43
@JamesMichaelHare I've read that as well but it always says "in some scenarios" I'm not sure if that fits the OPs scenario but saying StringBuilder as an alternative for string.join I would not think deserves a down vote? – user1231231412 Dec 06 '11 at 21:46
@JonC: I understand and accept your explanation. Also I noticed that I said "I'm not curious as to...". No idea what happened there, but I guess my question was obvious with the context. – Steve Rukuts Dec 06 '11 at 21:58
@JonC: I'm not the down-voter, so I don't know why he was down-voted. Sometimes that happens unfortunately and you never know who or why. Sometimes, unfortunately, it's even a petty attempt by some answers to push their answer up the list, but that's *really* rare. – James Michael Hare Dec 06 '11 at 21:58
@JamesMichaelHare No worries. I'm here to payback for the help I get from SO, not so much for "points". I just don't want to be a leech really. It would just help if someone told me what I was doing wrong with a downote. – user1231231412 Dec 06 '11 at 22:40
@JonC: I know, I really wish there was a place for a downvote comment (even if anonymous). I know they can put it in the comments, of course, but often they don't. – James Michael Hare Dec 07 '11 at 00:47

string.Join throws OutOfMemory Exception

3 Answers3