Question

I am trying to extract the first 200 words of a string and sometimes I get the following error:

"Index and length must refer to a location within the string. Parameter name: length"

The code is:

int i = GetIndex(fullarticle, 200);
string result = fullarticle.Substring(0, i);

How do I fix this?

Answer 1

It appears safe to assume the error is coming from string.Substring. Given that you get this error when startIndex + length > given.Length or startIndex < 0 or length < 0, GetIndex is either returning a value greater than fullarticle.Length or a negative number. The error exists in GetIndex so if you wish to carry on with the code you have, you should post the code of GetIndex to get the best answer.

If you’re up for something different, you could try this:

static string GetShortIntroduction(string phrase, int words)
{
    // simple word count assuming spaces represent word boundaries
    return string.Join(" ", phrase.Split().Take(words));
}