CRT Initialization

re: CRT Initialization

Tompa — Fri, 20 Oct 2006 22:55:35 GMT

Great - this is just the kind of post that I like to read! More of this 'under the hood' stuff please!

Thanks,

/Tompa

re: CRT Initialization

Emmanuel — Sat, 21 Oct 2006 21:06:06 GMT

Great - it is so amusing to really know something about this 'under the hood' kind of stuff. With Tompa, I would voice that we get something to read of such stuff (behind the scenes subjects).

Thanks,

Emmanuel

re: CRT Initialization

cpizano — Thu, 02 Nov 2006 19:14:42 GMT

it would be nice to talk about what happens if an exception is thrown at the initializers

re: CRT Initialization

Bhavesh — Tue, 07 Nov 2006 14:23:01 GMT

Hi,I am still not be able to understand what you talked.But i am veri interested and also require some help on CRT Startup code.

re: CRT Initialization

Vipul Garg — Thu, 09 Nov 2006 17:18:39 GMT

Hi,

I don't have basic concepts of CRT and i m very much interested to have some reference material on that.

re: CRT Initialization

grmileka — Fri, 10 Nov 2006 23:24:10 GMT

Thanks for the positive feedback!

cpizano,

Throwing an exception during the execution of initializers is indeed very important to understand... I'll see if I have some handy material on that subject...

re: CRT Initialization

grmileka — Fri, 10 Nov 2006 23:25:28 GMT

Forgot to sign my last entry :)

George Mileka

Visual C++ Libraries Team

re: CRT Initialization

George Mileka — Fri, 10 Nov 2006 23:42:47 GMT

Bhavesh and Vipul,

Unfortunately, I'm not aware of any books that discuss the internal implementation of the Microsoft CRT.

However, one very good book about CRT is:

The Standard C Library - by P. J. Plauger

George Mileka

Visual C++ Libraries Team

My homepage

Troy — Wed, 22 Nov 2006 17:58:57 GMT

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Converting to MSBuild

Visual C++ Team Blog — Thu, 07 Dec 2006 02:04:14 GMT

Hi, My name is Andreea Isac and I’ve been a member of the Visual C++ Libraries team for one year and

re: CRT Initialization

Albert Kennis — Thu, 07 Dec 2006 07:13:51 GMT

One question and one request please.

Let's say that we want to ensure the availabilty of some resource before main gets called. For example:

/* globals */

Logger l("log.txt");

As per your article, the CRT initilization will construct l before calling main.

My question is: what happens if l's constructor throws an exception? Is this bad practice?

Also, at what point will l's destructor be executed?

And, on a somewhat related / unrelated subject, can someone direct me to documentation on the __ImageBase construct that the MS C compiler / linker automagically installs into binaries. What other utterly useful fields are available?

Thanks - great blog.

re: CRT Initialization

Ben Anderson - MSFT — Fri, 09 Feb 2007 02:49:30 GMT

Albert - it is indeed bad practice to create a global variable using a constructor which may throw an exception since you have no way of catching it. I believe the default behavior if an exception is thrown at that point is to terminate, but I'd have to check the standard to be sure.

However, there is a solution to this problem, which is to construct such an object inside the initializer of a global object and surround the construction in a try/catch block. The pseudocode is something like:

int InitFunc();

Logger *l;

int gDummy = InitFunc();

int InitFunc()

{

try {

l = new Logger("log.txt");

} catch (...) {

// error handling

...

}

void Cleanup()

{

delete l;

}

int main()

{

...

Cleanup();

}

The alternative of course would be to not allow the constructor of Logger which is being called to throw an exception. This could be achieved by either not calling throwing code in the constructor, or try/catching and doing error handling inside the constructor. If you are using the logger class elsewhere in your code where you would like it to throw you can always create an overload that doesn't by adding a dummy parmeter like so:

// nonthrowing constructor

Logger::Logger(const string& filename, int dummyNoThrow)

{

try {

InitHelp(filename);

} catch (...) {

...

// error handling

}

// could throw

Logger::Logger(const string& filename)

{

InitHelp(filename);

}

re: CRT Initialization

Patrick Scott — Tue, 13 Mar 2007 16:45:16 GMT

What is the best pratice for the initialization of a large structure of elements, usually the sturcture is not modified, (communication message structures), with portions needing to be filled in during run time.