Question

I want to keep a string to another string strTotal from a richtextbox. then i want to split it into two SubString like firstPart and secondPart by a middle index say: midIndex.

Then I want to change some value in firsthalf and join with secondhalf. And finally show it to the richTextBox.

For this i used this code:

For my Last debug:

rtxtQueryPan.Text.Length = 53;
midIndex = 45;

 //string Totalqueryy = rtxtQueryPan.Text;
 string firstHalf = rtxtQueryPan.Text.Substring(0, midIndex-2); 
 string secondHalf = rtxtQueryPan.Text.Substring((midIndex- 1), (rtxtQueryPan.Text.Length - 1)); // THIS LINE SHOWS ERROR

 string duplicateFirstHalf = firstHalf;
 firstHalf += " " + clColumnNames.Text + ",";
 rtxtQueryPan.Text = firstHalf+secondHalf;

In the 3rd Line of the code says:

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

I have checked the length, midIndexvalue etc. But found no clue.

Answer 1

C#’s .Substring function takes a length, not a position as its second argument.

Thus, you probably wanted to write the following code:

rtxtQueryPan.Text.Substring(midIndex-1, (rtxtQueryPan.Text.Length-1) - midIndex);

Also, the length argument is optional, and not something you should provide in your case, as you want the rest of the string included. You can also therefore write:

rtxtQueryPan.Text.Substring(midIndex-1);