C# – HttpContext in .net standard library

.net-standardasp.net-corecnet

I am working on couple of projects one of which is an ASP.NET 4.5 application and other one is .Net Core API 1.1 project. The asp.net application is using HttpContext classes to read cookies and page headers. Now, I need to move this to a .net standard library which can be used by both the project. I don't find HttpContext in .net standard SDK. Any suggestions?

Best Answer

There's a problem to your approach: .NET Standard is the most bare-bones implementation of .NET available, meaning that only basic features which are platform- and scenario-agnostic are implemented.
HttpContext exists on both the .NET Framework and .NET Core (both of which implement .NET Standard, by the way), but being specific to the Web, it does not exist on .NET Standard.

So, you have three options:

Target the .NET Framework and use System.Web.HttpContext
Target .NET Core and use Microsoft.AspNetCore.Http.HttpContext
Move the logic that uses HttpContext away from the .NET Standard project

Do notice, though, that those classes vary greatly. The .NET Core version was created for ASP.NET Core which is vastly different to ASP.NET 4.5 and olders.

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.net – Difference between decimal, float and double in .NET

float and double are floating binary point types. In other words, they represent a number like this:

10001.10010110011

The binary number and the location of the binary point are both encoded within the value.

decimal is a floating decimal point type. In other words, they represent a number like this:

12345.65789

Again, the number and the location of the decimal point are both encoded within the value – that's what makes decimal still a floating point type instead of a fixed point type.

The important thing to note is that humans are used to representing non-integers in a decimal form, and expect exact results in decimal representations; not all decimal numbers are exactly representable in binary floating point – 0.1, for example – so if you use a binary floating point value you'll actually get an approximation to 0.1. You'll still get approximations when using a floating decimal point as well – the result of dividing 1 by 3 can't be exactly represented, for example.

As for what to use when:

For values which are "naturally exact decimals" it's good to use decimal. This is usually suitable for any concepts invented by humans: financial values are the most obvious example, but there are others too. Consider the score given to divers or ice skaters, for example.
For values which are more artefacts of nature which can't really be measured exactly anyway, float/double are more appropriate. For example, scientific data would usually be represented in this form. Here, the original values won't be "decimally accurate" to start with, so it's not important for the expected results to maintain the "decimal accuracy". Floating binary point types are much faster to work with than decimals.

C# – Could not load file or assembly … An attempt was made to load a program with an incorrect format (System.BadImageFormatException)

I am pretty sure you're having a 32-bit / 64-bit conflict. It sounds like your main project might be set to 32-bit while the class its referencing is set to 64-bit. Try looking at this SO question and this one too. Between the two of them, you should be able to figure out your problem.

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Related Solutions

.net – Difference between decimal, float and double in .NET

C# – Could not load file or assembly … An attempt was made to load a program with an incorrect format (System.BadImageFormatException)

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