String builder problems....

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Hi All,

I am trying to use a StringBuilder to construct a string in an odd format ie
"00 00 00 00 " can someone who is a bit more versed with the string builder tell me what I am doing wrong. the code I have is below

C#

string Credit_Value_String = "00000000";

         StringBuilder ValueUPDwn = new StringBuilder();


         MessageBox.Show("Value is: " + numericUpDown1.Value.ToString());

         //if (IsNumeric(numericUpDown1.Value))
        // {

            for (int i = 0; i <= Credit_Value_String.Length; i+=2)
             {
                  ValueUPDwn.Append(Credit_Value_String.Substring(i,2));
                  if (i < Credit_Value_String.Length - 2)
                  {
                      ValueUPDwn.Append(" ");
                  }

             }

             Credit_Value_String = ValueUPDwn.ToString();
             MessageBox.Show(Credit_Value_String);
        // }

Hovering over ValueUPDwn in debug shows the string in it space correctly "00 00 00 00" which is what is wanted (I'm going to take the value off a numeric up down tool later) however this does not run the length gets up to max (8) and it tries to go over the edge and gets lost. What I donot understand is I have used this method earlier with no problems...as I said I have not used StringBuilders very much in the past, as the code I am trying here has worked before in the project am I going to regret it when a gremlin crawls out later.
Glenn

Posted 25-Jan-13 5:06am

glennPattonWork3

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2 solutions

Solution 1

I think your problem was the fact that you are grabbing 1 char past the end of the string. In the function below the for loop has Credit_Value_String.length -1.

If your string is not an even number of chars you will also overrun the string length so added: (Credit_Value_String.Length < i+2) ?

C#

static string AnotherCrazyParsingMethod(string Credit_Value_String)
{
   StringBuilder ValueUPDwn = new StringBuilder();

   for (int i = 0; i < Credit_Value_String.Length; i += 2)
   {
       ValueUPDwn.AppendFormat("{0}{1} ", Credit_Value_String[i],           (Credit_Value_String.Length < i+2) ? '\0' : Credit_Value_String[i + 1]);
   }
   return ValueUPDwn.ToString();
}

Posted 25-Jan-13 5:30am

BC @ CV

Updated 25-Jan-13 6:04am

v6

Comments

glennPattonWork3 25-Jan-13 11:38am

Thanks for that, had problem, went took five minutes to look out window came back and thought oh <<bad word!>> let us hope no one sees, that I have asked this!

BC @ CV 25-Jan-13 11:40am

No worries. Sometimes it just takes another pair of eyes, ones that haven't been up all night staring at a text editor.

OriginalGriff 25-Jan-13 11:41am

You are right, but the easier way is to change the comparison to "less than". That way, the compiler can generate better code (becaus eit doesn't need the subtract) and the code is easier to read.

BC @ CV 25-Jan-13 11:45am

Nice. Thanks for the compiler tip, I didn't know that.

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OriginalGriff · Accepted Answer · 2013-01-25T05:31:00

Solution 2

You ran off the end of the string:

C#

for (int i = 0; i <= Credit_Value_String.Length; i+=2)

Should be:

C#

for (int i = 0; i < Credit_Value_String.Length; i+=2)

Posted 25-Jan-13 5:31am

OriginalGriff

Comments

glennPattonWork3 25-Jan-13 11:35am

Thank you Hangs Head in shame!

OriginalGriff 25-Jan-13 11:39am

We all do it :laugh:
Trouble is you tend to read what you meant to write...or at least I do!