what is DllImport

[mosini]

Hello.
I want to know deeply what does the statement below means:
............... ............... ............... ............... ............... ............... ............... .......
[DllImport("PrmC onnect.dll", CallingConventi on = CallingConventi on.Cdecl, EntryPoint = "OpenConnec t", ExactSpelling = true, CharSet = CharSet.Ansi)]

public static extern int OpenConnect(int nComType, [MarshalAs(Unman agedType.LPStr)] String Param);
............... ............... ............... ............... ............... ............... ............... ....

mean first why we use DLLImport?

Second what is CallingConventi on for?

third why it is not possible to add a reference to "PrmConnect.dll " from Reference folder in solution explorer ?

forth what is the use of EntryPoint and ExactSpelling and CharSet?

fifth why here it is written the OpenConnect with extern and also what does
" [MarshalAs(Unman agedType.LPStr)] String Param " means?
Plz Help guys.

[debasisdas]

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