Text Comparison in c sharp

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I wrote a program to highlight a text in a list of words. For example "The boy is a good", if i want to highlight "boy" using indexOf, it will be highlighted. now the problem is for a statement like "The boy is a good boy", if i want to highlight the second boy, i dont know how, because its only the first boy that will still be highlighted. Pls help as am still some how new to c sharp.

Posted 28-Aug-13 23:28pm

Member 9769841

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Zoltán Zörgő 29-Aug-13 5:32am

What is your problem:
- you can not find both "boy"'s starting index or
- you don't know how to highlight both non-continuous characters
How exactly do you look for matching substring, and ho exactly do you highlight in what sort of control?

Member 9769841 29-Aug-13 5:44am

Its a RichtextBox and may be when you see the codes, you will understand me. Its actually a application that compares the text in RichtextBox1 to the text in RichtextBox 2. It then highlights the diffrent portion in richtextBox2. Have been able to do that, except that it highlights the first occurence of the diffrent text. Here is the code....

public void check()
{
string[] RichTextBoxLines1 = dragDropclass1.Lines;
string[] RichTextBoxLines2 = dragDropclass1.Lines;

List<string> Test1 = new List<string>(dragDropclass1.Text.Split(new char[] {' '}));
List<string> Test2 = new List<string>(dragDropclass2.Text.Split(new char[] {' '}));

if (Test1.Count > Test2.Count)
{
for (int i = 0; i <= Test1.Count - Test2.Count; i++)
{
Test2.Add(" ");
}
}
else if (Test2.Count > Test1.Count)
{
for (int i = 0; i <= Test2.Count - Test1.Count; i++)
{
Test1.Add(" ");
}
}

bool[] value = new bool[Test1.Count];
for (int i = 0; i < Test1.Count; i++)
{
string a = Test1[i];
string b = Test2[i];
value[i] = string.Equals(a, b, StringComparison.Ordinal);

}

for (int i = 0; i < value.Length; i++)
{
if (value[i] == false)
{
int k = i + (i - 1);

// int s = dragDropclass2.Text.IndexOf(Test2[i], Test2[i].IndexOf(Test2[i]),Test2[i].Length);
dragDropclass2.SelectionStart = dragDropclass2.Text.IndexOf(Test2[i],k);
dragDropclass2.SelectionLength = Test2[i].Length;
dragDropclass2.SelectionColor = Color.Red;

}

}

Test1.Clear();
Test2.Clear();

}

Where Dragdropclass are the control i created to enable me drag text file into the richtextBox.

lukeer 29-Aug-13 7:59am

Please move that code to the question. Use the "Improve question" link for that.
And wrap code in tags like these: <pre lang="c#">YourCodeHere();</pre>
That way it will be nicely formatted and therefore readable.

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**Joezer BH** · Answer 1 · 2013-08-28T23:34:00

Solution 2

Two options:

using String.IndexOf:

C#

int SecondIndexOf(string theString, string toFind)
{
    int first = theString.IndexOf(toFind);

    if (first == -1) return -1;

    // Find the "next" occurrence by starting just past the first
    return theString.IndexOf(toFind, first + 1);
}

Using Regex:

C#

public static int NthIndexOf(this string target, string value, int n)
    {
        Match m = Regex.Match(target, "((" + value + ").*?){" + n + "}");

        if (m.Success)
            return m.Groups[2].Captures[n - 1].Index;
        else
            return -1;
    }

Cheers,
Edo

Posted 28-Aug-13 23:34pm

Joezer BH

Updated 29-Aug-13 1:20am

v2

Comments

Member 9769841 29-Aug-13 5:50am

Thanks..for the advice, i will really use that next time

Joezer BH 29-Aug-13 6:00am

Why "next time"? did you solve it in a different way?

Member 9769841 29-Aug-13 7:37am

i meant that i will make use of the comment box to reply to answers; like you told me to

Joezer BH 29-Aug-13 7:40am

Ah, yes for got about that msg...

:)

Mithiten · Answer 2 · 2013-08-28T23:31:00

Solution 1

First You Have To Check Condition That How Many Times That Word Is In That Row When Its Find Then Give Index Of It....

Posted 28-Aug-13 23:31pm

Mithiten

Comments

Member 9769841 29-Aug-13 5:37am

The thing is, The text are dynamic text, and it might even actually be numerous of lines of text...
What am working on is something that identifies the diffrent portion of another text. have been able to do that. But instead of highlighting the Text at the exact position, it highlights the first occurrence of that Text.

Mithiten 29-Aug-13 5:49am

String Comparison constants result in the same value from the IndexOf method. The String Comparison enum is important

V.Lorz · Answer 3 · 2013-08-29T00:09:00

Perhaps this could help. This function locates all the occurrences of the text you're looking for:

XML

private List<Match> FindOccurrences( string SourceText, string Expression )
{
    List<Match> Result = new List<Match>();

    Regex Parser = new Regex( Expression, RegexOptions.Compiled );

    Match Match = Parser.Match( SourceText );

    while (Match.Success)
    {
        Result.Add( Match );
        Match = Match.NextMatch();
    }

    return Result;
}

You can call the function simply like this:

List<Match> Matches = FindOccurrences( "This contains boy here and again contains boy here", "boy" );

The property Index of the objects of type Match contains the position into the input string.

Text Comparison in c sharp

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