Databases
StackOverflow2013
Postsdbo
POUnsafe string creation from char[]
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POUnsafe string creation from char[]
    primarykey
    data
    text
    <p>I'm working on a high performance code in which this construct is part of the performance critical section.</p> <p>This is what happens in some section:</p> <ol> <li>A <code>string</code> is 'scanned' and metadata is stored efficiently.</li> <li>Based upon this metadata chunks of the main string are separated into a <code>char[][]</code>.</li> <li>That <code>char[][]</code> should be transferred into a <code>string[]</code>.</li> </ol> <p>Now, I know you can just call <code>new string(char[])</code> but then the result would have to be copied.</p> <p>To avoid this extra copy step from happening I guess it must be possible to write directly to the string's internal buffer. Even though this would be an unsafe operation (and I know this bring lots of implications like overflow, forward compatibility).</p> <p>I've seen several ways of achieving this, but none I'm really satisfied with.</p> <p>Does anyone have true suggestions as to how to achieve this?</p> <p><strong>Extra information:</strong><br> The actual process doesn't include converting to <code>char[]</code> necessarily, it's practically a 'multi-substring' operation. Like 3 indexes and their lengths appended.</p> <p>The <code>StringBuilder</code> has too much overhead for the small number of concats.</p> <p><strong>EDIT:</strong><br> Due to some vague aspects of what it is exactly that I'm asking, let me reformulate it.</p> <p>This is what happens:</p> <ol> <li>Main string is indexed.</li> <li>Parts of the main string are copied to a <code>char[]</code>.</li> <li>The <code>char[]</code> is converted to a <code>string</code>.</li> </ol> <p>What I'd like to do is merge step 2 and 3, resulting in:</p> <ol> <li>Main string is indexed.</li> <li>Parts of the main string are copied to a <code>string</code> (and the GC can keep its hands off of it during the process by proper use of the <code>fixed</code> keyword?).</li> </ol> <p>And a note is that I <em>cannot</em> change the output type from string[], since this is an external library, and projects depend on it (backward compatibility).</p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USAidiakapi
    1. USAidiakapi
    plurals
    1. PL
      singulars
      1. LTLinked
    2. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POUnsafe string creation from char[]
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POUnsafe string creation from char[]
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POUnsafe string creation from char[]
      1. This table or related slice is empty.
      1. VTUpMod
    1. COWhat do you actually have to do with the strings after all this? That is, instead of trying to find ways to map to `string[]` without copying again, can you just bring it in as a `char[]` and then store `int,int` pairs of the position & length of the sub-parts you need, referencing the original array to pull out the substrings whenever you need them?
      singulars
      1. POUnsafe string creation from char[]
      1. USJamie Treworgy
    2. COI'm not really sure what code you are trying to enhance here.
      singulars
      1. POUnsafe string creation from char[]
      1. USAndrew Barber
    3. COThe string class is special; it is by definition immutable and involves copying. Trying to circumvent this is asking for trouble with the GC and other managed code (strings are pooled).
      singulars
      1. POUnsafe string creation from char[]
      1. USNikki9696
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload