Can anyone see anything wrong about this small segment?

[mcleano]

 void appendErrorLog(std::string tag, Error *ptr)
{
	static int size = ptr->invalidTags.size();

	ptr->invalidTags.resize(size+1);
	ptr->invalidTags.push_back(tag);
	std::cout << "\n --- " << tag << " --- "; // debugging

	ptr->invalidTagsIndex = ptr->invalidTags.size();

	return;
}

invalidTags is a vector of std::strings
invalidTagsIndex is just an integer

EDIT* Or perhaps a problem I that might be happening because i'm not getting the expected results.

[tummychow]

Without the information for your side classes/objects, this diagnosis is very difficult.

[jsmith]

Well, for one thing the static is initialized only once, the first time into the function.

[mcleano]

Well, for one thing the static is initialized only once, the first time into the function.

What is the problem with that? I thought that was the point of a static int in a funciton like this. To retain its value after returning to the caller.

[tummychow]

I'm not sure but the call to size() may execute every time the function runs; I don't remember.

[jsmith]

It runs once.

I don't know if it's a problem -- you know the code that uses the function.

Example:

On first call to appendErrorLog, let's say ptr->invalidTags.size() returns 0.
Line 3 sets size to 0.
Line 5 resizes the invalidTags container to 1.
Line 6 adds the tag to the container.
Line 9 sets invalidTagsIndex to 1.

On second call to appendErrorLog, *whatever* ptr->invalidTags.size() is:
Line 3 is not executed;
Line 5 resizes the invalidTags container to 1.
Line 6 adds the tag to the container.
Line 9 sets invalidTagsIndex to 1.

On third call to appendErrorLog, *whatever* ptr->invalidTags.size() is:
Line 3 is not executed;
Line 5 resizes the invalidTags container to 1, which has the effect of dropping the second tag.
Line 6 adds the new tag to the container.
Line 9 sets invalidTagsIndex to 1.

etc.

On the surface it seems wrong to me.

[mcleano]

Yes! That is what is happening and it took the step-through of your post to show me why, so thank you.

However, I have a small problem with the new code, the container seems to be increasing in size by 2 when all I need is 1. Take this code:

 void appendErrorLog(std::string tag, Error *ptr)
{
	int static size;

	if(ptr->invalidTags.empty())
		size = 0;
	else
		size = ptr->invalidTags.size();

	ptr->invalidTags.resize(size+1);
	std::cout << "The size is " << ptr->invalidTags.size(); // debugging
	ptr->invalidTags.push_back(tag);
	std::cout << "\n --- " << tag << " --- "; // debugging

	ptr->invalidTagsIndex = ptr->invalidTags.size();

	return;
}

The output I get for this is:

 --- *tag* --- The size is 1
 --- *tag* --- The size is 3
 --- *tag* --- The size is 5
etc...

[jsmith]

You are misusing the container.

You do not need to resize() it to make room for a new element that you add via push_back().

resize() to size() + 1 actually adds a default constructed element to the end of the
container.

Your function can be as simple as

void appendErrorLog( const std::string& tag, Error& err ) {
    err.invalidTags.push_back( tag );
    err.invalidTagsIndex = err.invalidTags.size(); // Not sure why you need this?
}

[mcleano]

Yeah I'm not sure why I've actually put that there... Also, why have you used the object not the pointer?