Missing the point re: Arrays

Question

I am trying to write some code that maintains a running sum in an array...

I think I am missing the scope rules or do not understand the way that arrays are used ...

I am an experienced C (and many other language) programmer, but am new to C#, I did a few C++ programs 10 years ago.

In short, I think the OOP aspects have me hosed up.

I am trying to maintain a buffer in PlotDataSum, which gets PlotData1 added to it on every execution of a function called from a "read" button click.

This runs fine and I see the new data plotted from an array, but when I "turn-on" summation in that array, it appears (from debugging) that the PlotDataSum array arrives empty at each execution of the buffer read function, which means I am summing with nothing...I am trying to maintain this summation buffer until I decide to clear it...

What is the procedure to declare an array that has the required scope to not dissapear after every use...

I tried adding this array to an object of a class that pulls the same data from an external I/F...and referenced it using the obj.array[i] typical notation, whcih also worked the same...seemed to accept the last addition, but did not "remember" its sum until teh next time I tried to add something again.

So far I am finding C# is so "safe", it is VERY hard to get very simple things done...

A code sample is included below:

namespace critter

{

/// <summary>

/// Summary description for MainForm.

/// </summary>

public class MainForm : System.Windows.Forms.Form

{

public System.Windows.Forms.Button HelpBtn;

public System.Windows.Forms.CheckBox CBReadCont;

public System.Windows.Forms.Button SendRptsBtn;

etc...

//delacered as a local variable within the MainForm

double[] PlotDataSum = new double[275];

used later in a function associated with reading data...

// Plot the data...

for (i = 0; i < 275; i++)

{

PlotDataSum[i] += PlotData1[i];

}

if (CBEnableSum.Checked)

{

Plot1.PlotY( PlotDataSum );

}

else

{

Plot1.PlotY(PlotData1);

}

Any help would be appreciated. I am clearly missing soemthing VERY basic about scope rules...

Thanks

Jan Montano · Answer

hehe. Nice. Good for you you found it. :)

John Rogers · Answer

well...this is pretty embarrassing...I found a call that has been zeroing out the sum...so I have it fixed. So no mystery just a MISTAKE... Please just delete the code I sent...and don't waste your time. Thanks JPR

John Rogers · Answer

I sent a zipped set of the files.. Thanks JPR

Jan Montano · Answer

If you would like to you could email me the whole project and I would gladly take a look into it. JAN DOT MONTANO AT GMAIL DOT COM

John Rogers · Answer

No sir it's just a old fashioned array of double... for which I wanted to keep a running sum. I was disaplying PlotData1 but decided I wanted it to accumulate so I created one just like it (PlotDataSum) moved it father up into the Form declarations to give it the proper scope ( I thought) and I selectively add PlotData1 to it (when the appropriate checkbox is checked in another part of the form)...There's lot's of other things going on...a USB interface and load of heavy lifting to get that data into an object that I can use to harvest the data ...which is how I get PlotData1 in the first place. I jsut decided not to burden this (supposedly) simple question with those details...

Jan Montano · Answer

are you by any chance using PlotDataSum as a function parameter and actually modifying it inside that function? If not I can't think of any ideas anymore. It should just behave the way you think it should.

John Rogers · Answer

Jan For some reason my sum gets zeroed before each use...so I just see that latest data added in... not the summation. I am not closing the MainForm so I don't understand how it's being reset. I am thinkning about declaring another public array class with the array insisde and using/ referencing it that way...unless you or other readers have any other ideas. John

Jan Montano · Answer

You declared plotdatasum as a local variable in your MainForm. That's all the scope you will need. It will be not out of scope in anyway just as long as your MainForm is alive. Its values will not reset in anyway unless specified.