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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for October 22nd, 2013

.NET/C#: Type.IsSubclassOf Method versus Type.IsAssignableFrom

Posted by jpluimers on 2013/10/22

Every once in a while, you will have to do is checks using reflection.

Basically there are two methods:

Thanks to Ani and Werner Beroux for explaining the difference in more detail on StackOverflow, I added some extra links:

To check for assignability, you can use the Type.IsAssignableFrom method:

typeof(SomeType).IsAssignableFrom(typeof(Derived))

This will work as you expect for

but not when you are looking for ‘assignability’ across explicit / implicit conversion operators.

To check for strict inheritance, you can use Type.IsSubclassOf:

typeof(Derived).IsSubclassOf(typeof(SomeType))

–jeroen

via: c# – How to check if a class inherits another class without instantiating it? – Stack Overflow.

Posted in .NET, .NET 1.x, .NET 2.0, .NET 3.0, .NET 3.5, .NET 4.0, .NET 4.5, C#, C# 1.0, C# 2.0, C# 3.0, C# 4.0, C# 5.0, Development, Software Development | Leave a Comment »

Table with the Numeric Data Types in SQL Server

Posted by jpluimers on 2013/10/22

I couldn’t find a table with numeric data types in SQL Server 2012 on MSDN, but since they have not changed since SQL Server 2008,  I copied the table from Understand the 9 Numeric Data Types in SQL Server 2008, added an entry for bit, and links to the relevant SQL Server 2012 pages at MSDN.

Edit: somehow the WordPress editing system suppressed all the superscripts (for the powers of 2 and 10), so I replaced them with caret signs and powers of 2 and 10 to make it more clear and verified them against Floating point numbers and these Wikipedia pages:

Data Type Range of Values Storage Space

Data Type Range of Values Storage Space
tinyint 0 to 255 1 byte
smallint –32,768 to 32,767 2 bytes
int –2^31 to 2^31–1 4 bytes
bigint –2^63 to 2^63–1 8 bytes
decimal(p,s)
numeric(p,s)
–10^38+1 to 10^38–1 5 to 17 bytes
smallmoney –214,748.3648 to 214,748.3647 4 bytes
money –922,337,203,685,477.5808 to 922,337,203,685,477.5807 8 bytes
real –3.4*10^38 to –1.18*10^38, 0, and 1.18*10^38 to 3.4*10^38 4 bytes
float(n) –1.79*10^308 to –2.23*10^308, 0, and 2.23*10^308 to 1.79*10^308 4 bytes or 8 bytes
bit 0 to 1 0+ bytes

Later I found an even more complete table at SQL Server Data Types Reference – ConnectionStrings.com.

–jeroen

via: Understand the 9 Numeric Data Types in SQL Server 2008.

Posted in Algorithms, Database Development, Development, Floating point handling, Software Development, SQL Server, SQL Server 2008, SQL Server 2008 R2, SQL Server 2012 | Leave a Comment »

 
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