CODEWITHSUNDEEP
c++arraystemplatesruntime-error
Byron
Byron

Reputation: 231

Runtime Error Issues

Got a bit of code here thats giving me a runtime error that I cant seem to fix. The function Length() calculates the cumulative distance between all the points in an array of points. It uses a previously defined function Distance() that I know works perfectly. Any pointers?

Here is my source code for the function:

template<typename Point>                //Length function
double PointArray<Point>::Length() const
{
    double total_length = 0;
    for (int i=0; i<Size(); i++)
    {
        total_length += (GetElement(i)).Distance(GetElement(i+1));
    }
    return total_length;
}

And here is my implementation:

cout<<"The Length of the Point Array is: "<<(*ptArray1).Length()<<endl;

Many thanks!

Upvotes: 0

Views: 64

Answers (2)

Captain Obvlious
Captain Obvlious

Reputation: 20063

You are reading elements that are beyond the end of the array.

for (int i=0; i<Size(); i++)
{
    total_length += (GetElement(i)).Distance(GetElement(i+1));
                                                      //^^^
}

One you reach the end of the for loop you read the last element and then calculate the distance from the next element - which is outside the bounds of the array . Your for loop should look something like this:

for (int i=0; i<Size() - 1; i++)
{
    total_length += (GetElement(i)).Distance(GetElement(i+1));
}

Upvotes: 3

taocp
taocp

Reputation: 23634

Try this:

template<typename Point>                //Length function
double PointArray<Point>::Length() const
{
    double total_length = 0;
    for (int i=0; i<Size()-1; i++)
    {               //^^^ otherwise, i+1 will be out of range
        total_length += (GetElement(i)).Distance(GetElement(i+1));
    }
    return total_length;
}

Upvotes: 2

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