Finding floating points in a large string

Question

I have a large string that has a series of floating points in string. A typical string would have Item X $4.50 Description of item \r\n\r\n Item Z $4.75... There is really no rhyme or reason for the text. I have the lowest already and I need to find all the values in the string. So if it was 10.00 it would find every value that is 10.05 or less. I would assume that some sort of regex would involved to find the values and then I could put them in an array then sort them.

So it would be something like this to find the which of those values fit my criteria.

int [] array;
int arraysize;
int lowvalue;
int total;

for(int i = 0; i<arraysize; ++i)
{
    if(array[i] == lowvalue*1.05) ++total;
}

My problem is getting those values in the array. I have read this but d+ does not really work with floating points.

Just to be clear, do you need all the values below `10.00`, or are you specifically looking for the smallest value? — StriplingWarrior, Jul 19 '11 at 21:52
@StriplingWarrior that was a typo it would have to be all value 105% of the lowest value or less. — Joe Tyman, Jul 20 '11 at 03:18
Just the values, or do you need the descriptions that go along with those values once you have them? — Nathan, Jul 20 '11 at 04:53

Icemanind · Accepted Answer · 2011-07-20T20:17:03.110

6

You should use RegEx:

Regex r = new RegEx("[0-9]+\.[0-9]+");
Match m = r.Match(myString);

Something like that. Then you can just use:

float f = float.Parse(m.value);

If you need an array:

MatchCollection mc = r.Matches(myString);
string[] myArray = new string[mc.Count];
mc.CopyTo(myArray, 0);

EDIT

I just created a small sample application for you Joe. I compiled it and it worked fine on my machine using the input line from your question. If you are having problems, post your InputString so I can try it out with that. Here is the code I wrote:

static void Main(string[] args)
{
    const string InputString = "Item X $4.50 Description of item \r\n\r\n Item Z $4.75";

    var r = new Regex(@"[0-9]+\.[0-9]+");
    var mc = r.Matches(InputString);
    var matches = new Match[mc.Count];
    mc.CopyTo(matches, 0);

    var myFloats = new float[matches.Length];
    var ndx = 0;
    foreach (Match m in matches)
    {
        myFloats[ndx] = float.Parse(m.Value);
        ndx++;
    }

    foreach (float f in myFloats)
        Console.WriteLine(f.ToString());

    // myFloats should now have all your floating point values
}

edited Jul 20 '11 at 20:17

answered Jul 19 '11 at 21:52

Icemanind

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You can't copy matches to a collection of strings. – svick Jul 19 '11 at 23:57
@svick - [This says you can](http://msdn.microsoft.com/en-us/library/system.text.regularexpressions.matchcollection.copyto.aspx). It should copy the MatchCollection items into an array, then you can just iterate through the array and utilize the Value property to get the strings. – Icemanind Jul 20 '11 at 04:00
That says you can copy to an array. It doesn't say you can copy to an array of strings. And your code doesn't actually work, `CopyTo()` throws `InvalidCastException`. – svick Jul 20 '11 at 07:33
@icemanind this is giving is really odd results. It is pulling things that are even part of the string. – Joe Tyman Jul 20 '11 at 19:09
@Joe - hmmm that is very weird. I threw my answer together quick. Give me a couple of minutes and I will re-edit my answer with one that I tested using your input string from your question. – Icemanind Jul 20 '11 at 19:59
Some LINQ would probably shorten this right up. e.g. `var myFloats = mc.Select(m => float.Parse(((Match)m).Value)).ToArray();` – Ben Voigt Jul 20 '11 at 20:23
@Ben - Agreed. LINQ can definitely help out. – Icemanind Jul 20 '11 at 20:27

Finding floating points in a large string

1 Answers1