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IntelliSense Bug In VS.NET

, 27 Mar 2002
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Occasionally IntelliSense stops working and you are hard pressed to find out why. Here is one reason that I have discovered.
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I have been irritated at times when MS IntelliSense stops working in the middle of programming. Sometimes the whole thing quits and at other times only certain sections of code fail to bring up Auto List Members and Parameter Info. Luckily, today I discovered one reason. Hopefully someone can help determine other situations that cause IntelliSense to fail.

I have grown to depend on IntelliSense when learning new libraries of functions. One such library is the GDI+ library. If you have not yet looked into it, I highly recommend you drop what you are doing and start now. Chances are, you are wasting a lot of time writing code that the GDI+ already does on its own. Anyhow, I was writing a sample application to check out features in the library when my IntelliSense stopped working. Irritated, I decided to figure out why.

After tinkering for a half hour I found one silly line in my code that brought IntelliSense to a stand-still. And you don't even need to be working with GDI+. Any code in VS.NET that uses a comma-list to define an array of object parameters will kill IntelliSense for all code following the definition.

The Problem

The problem is quite specific in this case. An array definition that includes object constructors to create elements confuses VS.NET and shuts down IntelliSense. Such a line is found in the following example.

void OnPaint(HDC hdc)
    Graphics graphics(hdc);

    // IntelliSense works here.

    Point arrayPoints[] = {Point(2,3), Point(5,7), Point(10,5)};

    // IntelliSense does NOT work here

The Workaround

Unfortunately, the long-hand version of the same code is the way to go. This is really terrible for cases where more elements could be added or removed later. I won't venture a guess as to how many people would like to chide me for suggesting that code be switched as in this work-around. But it seems that if you want IntelliSense to work, you need to do this (or join me in telling Microsoft about this problem and hope the fix it).

void OnPaint(HDC hdc)
    Graphics graphics(hdc);

    // IntelliSense works here on graphics object

    Point arrayPoints[3];
    arrayPoints[0] = Point(2,3);
    arrayPoints[1] = Point(5,7);
    arrayPoints[2] = Point(10,5);

    // IntelliSense works just fine

A Better Work Around

Special thanks to Anonymous for responding to this article with this work-around. I am adding it to the article so it won't be missed in the messages below. Notice that the array brackets are after the type not the identifier.

void OnPaint(HDC hdc)
    Graphics graphics(hdc);

    // IntelliSense works here on graphics object

    Point[] arrayPoints = {Point(2,3), Point(5,7), Point(10,5)};

    // IntelliSense works just fine

A Sidenote

Fortunately, this problem does not appear to affect simple arrays.

void OnPaint(HDC hdc)
    Graphics graphics(hdc);

    // IntelliSense works here on graphics object

    int oddNumbersLessThanTen[] = {1,3,5,7,9};
    char crookedLetters[] = "BCDGJOPQRSU";

    // IntelliSense works just fine


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About the Author

Tom Welch
Software Developer (Senior)
United States United States
No Biography provided

Comments and Discussions

Generalgood find PinmemberDonsw21-Aug-09 18:15 
GeneralBrackets Pinmemberaschwel8-Feb-07 23:36 
GeneralMore Causes PinmemberSynetech20-Jan-07 21:22 
NewsIDE Quick Watch, Framework 1.1 switch bug PinmemberReza Aghazadeh8-Apr-06 21:39 
GeneralRe: IDE Quick Watch, Framework 1.1 switch bug Pinmembermkisaacs7-Nov-06 14:49 
GeneralStill alive in VS 2005 Beta2 PinmemberNicolasG2-Jul-05 11:39 
GeneralAnother reason why it breaks PinmemberJohn Cardinal15-Apr-05 18:05 
GeneralIntellisense does not work after &quot;std::somename&quot; PinsussAnonymous5-Aug-03 0:18 
GeneralIntellisense does not work after &quot;std::somename&quot; PinsussAnonymous5-Aug-03 0:14 
GeneralSome more info PinmemberBeliever30-Jul-03 12:34 
Thanks for the article Tom. At one stage I thought I was the only one having this problem. I did a re-install of VS.Net thinking perhaps that something might have gone wrong with my VS.NET 2003 update. Of course, the problem still continues.
MS states in VS.Net that intellisense may become unavailable in some situations including:
There are certain cases when the IntelliSense options may not work as you expect.
There is a code error above the cursor
If there is an incomplete function or other coding error above the location of the insertion point, IntelliSense may be unable to parse the code elements and therefore will not work. You can comment out the applicable code to enable IntelliSense again.

However I've noticed that when Intellisense fails, even when you fix your code while editing it still doesn't come back. The symptoms are the same as Tom explained: all the colored fonts disappear, no autolist and so forth. Worst still, try to do a copy and paste and the IDE comes back with the crude message: VS IDE: Copy/Paste error. If you had done a cut/paste you might as well kiss goodbye to what you had put in the clipboard. The IDE becomes unable to perform any Undo/Redo. Yesterday, I kept working while the intellisense was gone, and got the message saying I had to save my work and exit the VS IDE :-Dbecause a memory corruption had occurred!
I've been coding in both C# and and noticed that this behaviour only happens with C#, and not with VB.
The only way I've known to restore the IDE and get Intellisense back on track is by switching between the code screen and design screen, if you're working on a form.
I've no doubt MS will fix the problem. However I find a bit disappointing that a tool like VS.Net being touted as a high-level productivity tool can make us waste precious programming time trying to cope with problems like that.
Having said all that, overall I am very satisfied with MS efforts in making VS.Net a reality and believe the solution of the problem will come soon.

GeneralIntellisense for Web Services PinmemberLoai7-Apr-03 11:11 
GeneralIt doesn't work everytime in VC++ 6 too! PinmemberRickard Andersson1-Apr-02 2:56 
GeneralWrong section IMHO PinmemberNish [BusterBoy]28-Mar-02 22:06 
GeneralRe: Wrong section IMHO PinmemberTom Welch29-Mar-02 3:00 
GeneralRe: Wrong section IMHO PinmemberNish [BusterBoy]29-Mar-02 19:16 
GeneralVisual Assist for VS.NET PinmemberTim Hodgson17-Mar-02 7:11 
GeneralRe: Visual Assist for VS.NET Pinmemberwilliamsu23-Feb-08 19:03 
GeneralNo intelligence in the IntelliSense! PinmemberPaul Selormey11-Mar-02 23:51 
GeneralRe: No intelligence in the IntelliSense! PinmemberTom Welch12-Mar-02 10:40 
GeneralRe: No intelligence in the IntelliSense! PinmemberAnonymous17-Mar-02 13:47 
GeneralRe: No intelligence in the IntelliSense! PinmemberJason Gerard28-Mar-02 11:07 
GeneralRe: No intelligence in the IntelliSense! PinmemberTom Welch28-Mar-02 11:30 
GeneralRe: No intelligence in the IntelliSense! PinmemberMr. Tibbs1-Apr-02 8:21 
GeneralRe: No intelligence in the IntelliSense! PinmemberVictor Boctor22-Apr-03 19:07 
GeneralRe: No intelligence in the IntelliSense! [modified] PinmemberHenry Venn23-Sep-07 19:10 

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