C# Discussion Boards - CodeProject

Member 133187482-Apr-20 4:52

2-Apr-20 4:52

Dear All,

I am beginner in C# and I am building an application to create a workbook (Book1.xlsx) then copy a specific sheet from another workbook ( Book2.xlsx ).

I created Book1 but I am trying to copy Sheet1 from Book2 but I could not.

before copying [Sheet1 from Book2 ] I am dong a kind of check to collect names for all opened workbooks so I could not be able to get names of workbooks which opened by Visual Studio c# by the below piece of code but If will open the same workbooks by myself I found the below code can get the name of opened workbooks without problem.

I don't know why.

 public void CopyAsiRefSheet()
        {

 Microsoft.Office.Interop.Excel.Application XAPP;

      XAPP = (Microsoft.Office.Interop.Excel.Application)System.Runtime.InteropServices.Marshal.GetActiveObject("Excel.Application");

            foreach (Microsoft.Office.Interop.Excel.Workbook WB in XAPP.Workbooks)
            {

                
                MessageBox.Show(WB.Name);

            }
}

Thanks,
Moelsayed

Re: Get names for all opened Workbook

Richard MacCutchan2-Apr-20 5:50

Richard MacCutchan

2-Apr-20 5:50

You need to study the documentation at Microsoft.Office.Interop.Excel Namespace | Microsoft Docs[^]. It explains how to access the various elements of a Workbook, Worksheet, cell collection, etc.

Editor, Visualization, C#

Calin Negru1-Apr-20 4:29

Calin Negru

1-Apr-20 4:29

I`m working on a graphics editor. I was trying to implement a gui in DirectX but I realised that`s not the right approach. I`m used to C# Forms so I was asking myself if I can stitch C# GUI (Forms) and C++ DirectX together. Any help is welcome.

Re: Editor, Visualization, C#

#realJSOP1-Apr-20 4:51

#realJSOP

1-Apr-20 4:51

WinForms is also not the right approach. Use WPF instead.

".45 ACP - because shooting twice is just silly" - JSOP, 2010
-----
You can never have too much ammo - unless you're swimming, or on fire. - JSOP, 2010
-----
When you pry the gun from my cold dead hands, be careful - the barrel will be very hot. - JSOP, 2013

Re: Editor, Visualization, C#

Calin Negru1-Apr-20 5:15

Calin Negru

1-Apr-20 5:15

Could you expand? I would like to use my existing C++ code base would that be possible?

Re: Editor, Visualization, C#

Dave Kreskowiak1-Apr-20 5:29

Dave Kreskowiak

1-Apr-20 5:29

That's impossible to answer since you are the only one who knows how that code is written and what it depends on.

Asking questions is a skill
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Google: C# How to debug code
Seriously, go read these articles.

Dave Kreskowiak

Re: Editor, Visualization, C#

Richard MacCutchan1-Apr-20 22:18

Richard MacCutchan

1-Apr-20 22:18

See Platform Invoke (P/Invoke) | Microsoft Docs[^] for how to use a C/C++ library in C#.

Re: Editor, Visualization, C#

Calin Negru1-Apr-20 22:49

Calin Negru

1-Apr-20 22:49

Ok, Thanks [edit] all C solution is probably what I`m looking for.

modified 2-Apr-20 5:13am.

European Car plate recognition

Member 1478897131-Mar-20 22:20

Member 14788971

31-Mar-20 22:20

Dear People!

I need a usable license plate recognition program for my thesis. I would like to use it for entry access control. I wrote my program in C# language and the recogniser should be detect plate from images. I really appreciate any help or suggestion.

I want to detect europen plates, especially Hungarian and area.

Can you help me?
Thank you for your help!

Re: European Car plate recognition

OriginalGriff31-Mar-20 22:42

OriginalGriff

31-Mar-20 22:42

Google is your friend: Be nice and visit him often. He can answer questions a lot more quickly than posting them here...

A very quick search gave over half a million hits: detect european number plates c - Google Search[^]
Start there, and begin reading.

In future, please try to do at least basic research yourself, and not waste your time or ours.

"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
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Memory Management in Unit Testing

User-862169531-Mar-20 19:20

User-8621695

31-Mar-20 19:20

Hi Dear,
I was writing on unit test using Nunit, and suddenly one question came in my mind. So my Unit test are beloe:

[TestMethod]
public void TestMethod()
{
string input ="1,2";
int output =3;
Add add= new Add();
var result= add.GetSum(input);
Assert.AreEqual(output, result);
}

Now my query is when we are defining any variable using string or int it will allocate some memory in heap or stack. So will that memory get de-allocated after completion of unit test?

OR What if will not define variables and pass values directly in Assert like below:

[TestMethod]
public void TestMethod()
{

Add add= new Add();
var result= add.GetSum("1,2");
Assert.AreEqual(3, result);
}

So what is the difference between both the unit tests in terms of performance and memory management?

Thanks

Re: Memory Management in Unit Testing

Richard MacCutchan31-Mar-20 21:04

Richard MacCutchan

31-Mar-20 21:04

User-8621695 wrote:
will that memory get de-allocated after completion of unit test?

Yes, since the scope of the variables is restricted to the test methods, they will be deallocated on return from the method.

Re: Memory Management in Unit Testing

Pete O'Hanlon1-Apr-20 0:24

Pete O'Hanlon

1-Apr-20 0:24

Something you need to consider when you put strings in place using syntax like string s1 = "1,2"; or myClass.CallMethod("3,4");; these strings are interned in the string pool. In other words, the string is not garbage collected until the tests finish and the AppDomain is unloaded.

Advanced TypeScript Programming Projects

Re: Memory Management in Unit Testing

F-ES Sitecore1-Apr-20 1:38

F-ES Sitecore

1-Apr-20 1:38

In terms of memory management they are the same. When you inline a string it still creates a string object which is stored in memory, the only difference is that it isn't assigned to a variable. Same with the int. In terms of performance, if you are in debug mode then you could argue the first version will perform worse due to the variable allocations, but we're talking single cpu cycles of difference. In release mode both of those code samples will effectively compile to the same code as the optimiser will inline the variables for you.

As for when they are deallocated, a test method is no different from any other method so the variables will be handled like normal.

Reference Types v. Value Types

Richard Andrew x6431-Mar-20 10:52

Richard Andrew x64

31-Mar-20 10:52

the .NET String class is a reference type, correct?

Why then must I add the ref keyword to a string argument if I want its value to be updated in the called function?

No other reference type behaves this way, correct?

Confused | :confused:

UPDATE: I just realized what's going on. Strings are immutable so when you pass a string with the ref keyword, it's the original reference to the string that is being updated with the new string. Without the ref keyword, the called function gets its own reference to the string, and if changes are made, then it's the function's reference that is updated, not the original reference. Smile | :)

The difficult we do right away...
...the impossible takes slightly longer.

Re: Reference Types v. Value Types

OriginalGriff31-Mar-20 11:42

OriginalGriff

31-Mar-20 11:42

Dat's de bunny!

"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
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Re: Reference Types v. Value Types

BillWoodruff31-Mar-20 12:31

BillWoodruff

31-Mar-20 12:31

I look at 'string as a chimera: a reference type (heap allocated [1], a class, no fixed allocation size, can be 'null) with value type semantics (immutability). Adding to the inter-species flavor is that == will compare content, not references. Under the hood a Char[].

[1] Eric Lippert's blogs illuminate the complexity of strings and memory allocation in .NET:

Quote:
"It is simply false that the choice of whether to use the stack or the heap has anything fundamentally to do with the type of the thing being stored. The truth is: the choice of allocation mechanism has to do only with the known required lifetime of the storage."

[^]
[^]

you'll have to look for these since @@^77!! MSDN has archived them:

http://blogs.msdn.com/b/ericlippert/archive/2009/04/27/the-stack-is-an-implementation- detail.aspx

http://blogs.msdn.com/b/ericlippert/archive/2009/05/04/the-stack-is-an-implementation- detail-part-two.aspx

http://blogs.msdn.com/b/ericlippert/archive/2010/09/30/the-truth-about-value-types.aspx

«One day it will have to be officially admitted that what we have christened reality is an even greater illusion than the world of dreams.» Salvador Dali

modified 31-Mar-20 23:25pm.

Re: Reference Types v. Value Types

Richard Andrew x6431-Mar-20 13:38

Richard Andrew x64

31-Mar-20 13:38

Thanks Bill! That's a very useful post.

The difficult we do right away...
...the impossible takes slightly longer.

Re: Reference Types v. Value Types

BillWoodruff31-Mar-20 18:38

BillWoodruff

31-Mar-20 18:38

here's a Lippert blog I find very relevant: Strings, immutability and persistence[^]

i like to confuse my students Smile | :)

by asking them: if a Point is a ValueType (immutable), why can you set its X/Y properties directly without creating a new copy. To (maybe) get across the idea that immutable and passed by value are not necessarily synonymous.

«One day it will have to be officially admitted that what we have christened reality is an even greater illusion than the world of dreams.» Salvador Dali

Re: Reference Types v. Value Types

F-ES Sitecore1-Apr-20 1:19

F-ES Sitecore

1-Apr-20 1:19

Richard Andrew x64 wrote:
the .NET String class is a reference type, correct?

No, it's a value type. Even though strings are heap-based, .net does smoke-and-mirrors behind the scenes to ensure strings behave like value types. Probably to make the language easier to use as strings are very common. The downside is that it can lead to poor performance if you're not aware of the caveats.

Re: Reference Types v. Value Types

Richard Deeming1-Apr-20 2:20

Richard Deeming

1-Apr-20 2:20

F-ES Sitecore wrote:
No, it's a value type.

No, it's an immutable reference type. There's not much in the way of smoke-and-mirrors involved; you can easily create your own immutable reference type to get the same behaviour.

If string was really a value type, you wouldn't sensibly be able to have a value type with a string member. The entire string would be stored "in-line" within that struct, and you'd end up with stack overflow exceptions everywhere.

It's probably better to say that in some circumstances it's easier to think of string as a value type, even though it isn't. Smile | :)

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Re: Reference Types v. Value Types

F-ES Sitecore1-Apr-20 2:38

F-ES Sitecore

1-Apr-20 2:38

Richard Deeming wrote:
it's easier to think of string as a value type, even though it isn't

Which is what I was saying.

Overloaded Methods with Generics

#realJSOP30-Mar-20 5:52

#realJSOP

30-Mar-20 5:52

I have the following methods:

public int MyMethod<T>(IEnumerable<T> data)...

public int MyMethod<T>(T data)...

When I call MyMethod with a collection, it always executes the (T data) version. I understand why, but the only way I know of to fix it is to add a dummy parameter to the method prototype so the two overloads are different.

Is there a way to fix it so that I don't have to add the dummy parameter?

Re: Overloaded Methods with Generics

OriginalGriff30-Mar-20 6:34

OriginalGriff

30-Mar-20 6:34

Not that I know of - although you can add constraints to a generic method, there is no way to say "where T : !IEnumerable" unfortunatly.

You could check the type in a single method and route it to one of two private methods?

"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
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Re: Overloaded Methods with Generics

#realJSOP30-Mar-20 6:50

#realJSOP

30-Mar-20 6:50

OriginalGriff wrote:
You could check the type in a single method and route it to one of two private methods?

I tried that, and it didn't want to work.

Frown | :(

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