String[] index number from regex search

alec

I have a string[] that I search using regex and it returns a list of elements in my string[] that match what I searched for using regex. I would like to find the index number of the elements that are returned.

example:

string[] StringArray = {"aaa","bbb","ccc","ddd","eee"};

string find = "bbb";

List FoundList = new List();

foreach (string Block in StringArray)
{
if (System.Text.RegularExpressions.Regex.IsMatch(Block, find,
System.Text.RegularExpressions.RegexOptions.IgnoreCase))
{
FoundList.Add(Block);
}
else
{
//do nothing
}
}

string[] FoundArray = FoundList.ToArray();

it will create FoundArray = {"bbb"} and I wish to find int i such that

StringArray[i] = FoundArray[0]

is true and for senarios where FoundArray has multiple entries I plan to loop it. Any help would be much appreciated.

5 Replies

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Amit Choudhary15y ago
perfect idea @vulpes you covered almost everything.. :) nice
Vulpes15y ago
Amit's idea of using a Dictionary will also give you a welding between the string and index.

However, StringArray.IndexOf(Block), will always give you the same index, even if there are duplicates found so you'd need to modify his code to use a 'for' rather than a 'foreach' loop.

The code for the Tuple approach would be:

string[] StringArray = {"aaa","bbb","ccc","ddd","eee"};

string find = "bbb";

List> FoundList = new List>();

for(int i = 0; i < StringArray.Length; i++)
{
string Block = StringArray[i];
if (System.Text.RegularExpressions.Regex.IsMatch(Block, find, System.Text.RegularExpressions.RegexOptions.IgnoreCase))
{
FoundList.Add(Tuple.Create(Block, i));
}
}

Tuple[] FoundArray = FoundList.ToArray();
Console.WriteLine(FoundArray[0].Item1);
Console.WriteLine("{0} : {1}", FoundArray[0].Item2, StringArray[FoundArray[0].Item2]);
alec15y ago
I am using .NET 4 and the welding seems like a good idea as I need the computer to know the index number not me (sorry for not saying that) and your solution Amit seems a bit high brow for a beginner such as myself but it looks like a good one can you recommend any links to see how the solution works so I can try and understand it a bit better? Thank you
Amit Choudhary15y ago
use a Map or Dictionary to store the matched string found with its associated index. you can find the index of element by StringArray.IndexOf(Block)

so you code would look like
Dictionary foundStrings=new Dictionary();

and inside the loop write below code with the FoundList.Add(Block)

foundStrings.Add(StringArray.IndexOf(Block), Block);

now you have everything you want..so you can loop through the dictionary and match the FoundList array Element..
Vulpes15y ago
There are several ways to do this.

Here's a simple one:

string[] StringArray = {"aaa","bbb","ccc","ddd","eee"};

string find = "bbb";

List FoundList = new List();
List IndicesList = new List();

for(int i = 0; i < StringArray.Length; i++)
{
string Block = StringArray[i];
if (System.Text.RegularExpressions.Regex.IsMatch(Block, find, System.Text.RegularExpressions.RegexOptions.IgnoreCase))
{
FoundList.Add(Block);
IndicesList.Add(i);
}
}

string[] FoundArray = FoundList.ToArray();
int[] IndicesArray = IndicesList.ToArray();
Console.WriteLine(FoundArray[0]); // bbb
Console.WriteLine("{0} : {1}", IndicesArray[0], StringArray[IndicesArray[0]]); // 1 : bbb

If you're using .NET 4.0, you could also use a List> to weld the found string and its index together.