Difference between array, arraylist, List, Hashtable, Dictionary and SortedList in c#

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Basic difference is that arrays are of fixed size. Whereas an ArrayList implements the list data structure and can dynamically grow. While arrays would be more performance that a list, a list would be far more flexible since you don't need to know the required size initially. Array - represents an old-school memory array - kind of like a alias for a normal type[] array. Can enumerate. Can't grow automatically. I would assume very fast insertion, retrieve and speed. ArrayList - automatically growing array. Adds more overhead. Can enum., probably slower than a normal array but still pretty fast. These are used a lot in .NET List - one of my favorites - can be used with generics, so you can have a strongly typed array, e.g. List . Other than that, acts very much like ArrayList. Hashtable - plain old hashtable. O(1) to O(n) worst case. Can enumerate the value and keys properties, and do key/val pairs. Dictionary - same as above only strongly typed via generics, such a...
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ASP.NET 4.0 potentially dangerous Request.Form value was detected issue resolved

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To resolve the issue of request validation, I added the following to the existing "page" directive in that .aspx file.

ValidateRequest="false"

But I still got the same error. Later I found that, for .NET 4, we need to add requestValidationMode="2.0" to the httpRuntime configuration section of the web.config file like the following:


<httpRuntime requestValidationMode="2.0"/>

But if there is no httpRuntime section in the web.config file, then this goes inside the <system.web> section.

If anyone wants to turn off request validation globally for a user, the following line in the web.config file within <system.web> section will help:


<pages validateRequest="false" /> 

Note: But always avoid the last example because there is a huge security issue. The request validation feature in ASP.NET provides a certain level of default protection against cross-site scripting (XSS) attacks.

However, we recommend that you analyze any request validation errors to determine whether existing handlers, modules, or other custom code accesses potentially unsafe HTTP inputs that could be XSS attack vectors.


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