Archive for the ‘.NET’ Category
Posted by jpluimers on 2013/08/14
Everyone knows there is a size difference between a gigabyte of memory, and a gigabyte of disk space.
The former is 102410241024, the latter is 100010001000.
To facilitate this, I’ve created a C# class UnitPrefixes containing quite a few constants and readonly values.
The class is below, but a few interesting facts first:
- Most values are const, but a few are readonly static variables because they cannot calculated at compile time (the C# compiler by design does very limited calculations at compile time; it is complex enough as it already is).
As Jon Skeet explains, there are some other differences between const and readonly static, which is why I favour const.
- Though all consts are positive, I could have used UInt32 and UInt64, but the .NET framework favours signed Int32 and Int64 types for parameters, so to avoid casting, I used the signed ones.
- There is no Int128 or UInt128, but there is System.Numerics.BigInteger which I use for values too large for 64-bit integers.
Note that BigInteger is relatively new, so this code will only work in C# 4 or higher, and requires .NET 4 or higher.
This is also the place where I use the public readonly static fields, as I need to call the BigInteger constructor to initialize it.
- I used the Decimal type, as the mantissa holds up to 28 digits of accuracy.
I used the Wikipedia pages Binary Prefix and Metric Prefix (I could also have used File Size) for the unit names and abbreviations.
Note that BitsPerByte is a const I needed too, and I will probably add constants for 512 and 4096, as you see those often in computing as well.
The below sample code is also available as a changeset on BeSharp.CodePlex.com. Read the rest of this entry »
Posted in .NET, .NET 4.0, .NET 4.5, C#, C# 4.0, C# 5.0, Conference Topics, Conferences, Development, Event, Jon Skeet, Software Development | Tagged: endregion, region | Leave a Comment »
Posted by jpluimers on 2013/08/08
Peter Leslie Morris asked if Delphi already incorporates the `yield` keyword that C# had introduced in C# 2.
Delphi doesn’t, but for the people interested what it does in C#:
Basically `yield` is syntactic sugar to make it a lot easier to write methods that return enumerators of some sort.
It delays (hence the yield keyword) execution until the enumerator as actually being used.
It is one of the hardest C# things to master (it is the most complicated transformation in the compiler, followed by anonymous methods – well maybe with the exception of async/await), but it can be very useful.
VB.NET doesn’t have it either (thanks André!) has it too, but and also has iterator blocks.
Some start posts on yield:
–jeroen
Posted in .NET, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, C#, C# 2.0, C# 3.0, C# 4.0, C# 5.0, Delphi, Development, Software Development | 10 Comments »
Posted by jpluimers on 2013/08/06
Posted in .NET, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, C#, C# 2.0, C# 3.0, C# 4.0, C# 5.0, Development, Software Development, VB.NET, VB.NET 10.0, VB.NET 11.0, VB.NET 8.0, VB.NET 9.0, Visual Studio 11, Visual Studio 2010, Visual Studio and tools | 7 Comments »
Posted by jpluimers on 2013/08/03
If you ever get something similar to
InvalidCastException: [A]Person cannot be cast to [B]Person.
then you are (or more precise: your process is) probably loading the same assembly twice, but from a different context.
.NET allows that, and for reason (side by side loading, appdomains, etc).
Delphi doesn’t (thanks Warren Postma for noticing). But a mistake you see quite often is that Delphi developers try to load the same Delphi type from both an EXE and a DLL wondering why they don’t match. If you want to spread your types in Delphi, then use BPLs (run-time packages) for that. BPLs are similar to .NET assemblies, but cannot be loaded in memory twice.
–jeroen
via c# – InvalidCastException for two Objects of the same type – Stack Overflow.
Posted in .NET, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, C#, C# 2.0, C# 3.0, C# 4.0, C# 5.0, Development, Software Development, VB.NET, VB.NET 10.0, VB.NET 11.0, VB.NET 8.0, VB.NET 9.0, Visual Studio 11, Visual Studio 2005, Visual Studio 2008, Visual Studio 2010, Visual Studio and tools | Leave a Comment »
Posted by jpluimers on 2013/07/25
Posted in .NET, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, C#, C# 2.0, C# 3.0, C# 4.0, C# 5.0, Delphi, Delphi XE2, Delphi XE3, Development, Software Development | 4 Comments »
Posted by jpluimers on 2013/07/23
Ever since I started .NET programming after .NET Beta 1 Arrived in 2001, I found that many people struggle with the relation between assemblies and namespaces.
So I was glad that I posted this answer about 2.5 years ago on StackOverflow. Below is the slightly edited form:
People are easily confused by the namespace/assembly thing, as it decouples the concept of where your code is physically located (the assembly) and how you reference it:
- logically reference is by using the namespace
- physical reference is by referencing the assembly
I usually explain the relation using the word contribute:
- An assembly can contribute to multiple namespaces.
For instance, the System.Data.dll assembly contributes to namespaces like System.Data (e.g. the class System.Data.DataTable) and Microsoft.SqlServer.Server (e.g. the class Microsoft.SqlServer.Server.SqlContext).
- Multiple assemblies can contribute to a single namespace.
For instance both the System.Data.dll assembly and the System.Xml.dll assembly contribute to the System.Xml namespace.
Which means that if you use the System.Xml.XmlDataDocument class from your project, you need to reference the System.Data.dll assembly.
And if you use the System.Xml.XmlDocument class, you need to reference the System.Xml.dll from your project.
(the above examples are .NET 4.0, but likely hold for previous .NET versions as well).
Danny Thorpe explained the concept of namespace and internal really well, so I won’t go into detail about those.
Ever since I started .NET courses 10 years ago, I draw a table explaining assemblies and namespaces like this:
–jeroen
via: C# assemblies, whats in an assembly? – Stack Overflow.
Posted in .NET, .NET 1.x, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, .NET CF, C#, C# 1.0, C# 2.0, C# 3.0, C# 4.0, C# 5.0, Development, Software Development | Leave a Comment »
Posted by jpluimers on 2013/07/18
A while ago, I wrote about .NET/C# duh moment of the day: “A char can be implicitly converted to ushort, int, uint, long, ulong, float, double, or decimal (not the other way around; implicit != implicit)”.
There is another duh moment having to do with the various C# operators like += which is being described as being
a += b
is equivalent to
a = a + b
You might think that this also holds:
a += b + c
is equivalent to
a = (a + b) + c
But Eric Lippert has explained this is not the case: it is equivalent to:
a = a + (b + c)
In his explanation, he also shows the confusion can get you very surprising results if you mix string, chars and ints in the expression: depending on the statement and ordering, you either concatenate characters, or add ints to characters.
He also recommends you should not do concatenation: either use String.Format, or StringBuilder. I totally agree with that.
Recommended reading!
–jeroen
Posted in .NET, C#, C# 1.0, C# 2.0, C# 3.0, C# 4.0, C# 5.0, Development, Software Development | Leave a Comment »
The Wiert Corner - irregular stream of stuff 