Passing a string to an unsafe struct.

Question

Hi Guys I need to interact with some old Delphi DLLs. Unfortunately they use the Delphi shortstring variable. Im having trouble accessing the DLL functions Im trying to pass in a string parameter when the function requires a Delphi shortstring variable. I found a reply online which suggested using a struct to create the shortstring variable in c# http://stackoverflow.com/questions/30569111/how-can-i-marshal-a-delphi-short-string-using-p-invoke I've pasted in the unsafe struct DelphiShortString struct to my code but Im now having trouble passing the string to the struct. DelphiShortString variablename; How to I pass a string to variablename? Thanks for your help.

Donald C · Answer

Hi Bhuvanesh Thanks for the reply. I have tried using StdCall [DllImport(Systir.dll EntryPoint = SystirFunction2 CallingConvention = CallingConvention.StdCall)] public static extern string SystirFunction2(Int64 SiteHash int Users string AuthKey); When calling the procedure using the following code: string SF2 = SystirFunction2(SK Users AuthKey); I get a PInvokeStackImbalance occurred error. The data Im passing in is identical the only difference I see is that Im using strings rather than the shortstrings that Delphi used. Id prefer it if I didn't have to use the struct to convert strtings to shortstrings but thats the only difference I can see at the moment. How do I go about passing a string to the struct? PS: What tags do you use when you want to display code? That looks far more readable than copying and pasting. Thanks again for your reply.

Bhuvanesh Mohankumar · Answer

Have you tried using Convention [DllImport( ServerTool.dll )CallingConvention=CallingConvention.StdCall)] Reference: https://msdn.microsoft.com/en-us/library/system.runtime.interopservices.callingconvention.aspx Mark as answer if helpful.