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Editorial Team
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Asked: 2026-05-13T18:09:16+00:00

I am completely new to C#, and need help converting a C++ structure to

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I am completely new to C#, and need help converting a C++ structure to C#. The C++ structure is given as:

#define QUE_ADDR_BUF_LENGTH 50
#define QUE_POST_BUF_LENGTH 11

typedef struct
    {
    const WCHAR *streetAddress;
    const WCHAR *city;
    const WCHAR *state;
    const WCHAR *country;
    const WCHAR *postalCode;
} QueSelectAddressType;

typedef struct
    {
    WCHAR   streetAddress[QUE_ADDR_BUF_LENGTH + 1];
    WCHAR   city[QUE_ADDR_BUF_LENGTH + 1];
    WCHAR   state[QUE_ADDR_BUF_LENGTH + 1];
    WCHAR   country[QUE_ADDR_BUF_LENGTH + 1];
    WCHAR   postalCode[QUE_POST_BUF_LENGTH + 1];
    } QueAddressType;

I cannot make changes to the C++ structure as they are defined by the API I am attempting to interface with. Any help would be appreciated.

EDIT:
Here is more information, the function in the dll I am attempting to call is declared the as follows:

#ifdef QUEAPI_EXPORTS
#define QueAPIExport __declspec(dllexport)
#elif defined QUEAPI_SERVER
#define QueAPIExport
#else
#define QueAPIExport __declspec(dllimport)
#endif

#ifdef __cplusplus
extern "C" {
#endif

typedef uint32 QuePointHandle;

QueAPIExport QueErrT16 QueCreatePointFromAddress
    (
    QueSelectAddressType*   addr,   // in:  Address data to search on.
    QuePointHandle*         point   // out: Handle to selected point. Must be closed with QueClosePoint.
    );

Here is how I have defined the DllImport:

[DllImport("QueAPI.DLL", EntryPoint = "QueCreatePointFromAddress")]
public static unsafe extern QueTypesnConst.QueErrT16 QueCreatePointFromAddress(QueTypesnConst.QueSelectAddressType *address, uint *point);

EDIT2:
The following code blocks were the solution to the problem:
For the Structures:

[StructLayout(LayoutKind.Sequential)]
public struct QueSelectAddressType
{
    [MarshalAsAttribute(UnmanagedType.LPWStr)]
    public string streetAddress;
    [MarshalAsAttribute(UnmanagedType.LPWStr)]
    public string city;
    [MarshalAsAttribute(UnmanagedType.LPWStr)]
    public string state;
    [MarshalAsAttribute(UnmanagedType.LPWStr)]
    public string country;
    [MarshalAsAttribute(UnmanagedType.LPWStr)]
    public string postalCode;
};

[StructLayout(LayoutKind.Sequential,CharSet=CharSet.Unicode)]
public struct QueAddressType
{
    [MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst=51)]
    public string streetAddress;
    [MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = 51)]
    public string city;
    [MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = 51)]
    public string state;
    [MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = 51)]
    public string country;
    [MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = 12)]
    public string postalCode;
};

For the DllImport:

[DllImport("QueAPI.DLL", EntryPoint = "QueCreatePointFromAddress")]
public static extern QueTypesnConst.QueErrT16 QueCreatePointFromAddress(ref QueTypesnConst.QueSelectAddressType address, ref uint point);
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1 Answer

  1. Editorial Team

    Try the following definition

    public partial class NativeConstants {

    /// QUE_ADDR_BUF_LENGTH -> 50
    public const int QUE_ADDR_BUF_LENGTH = 50;

    /// QUE_POST_BUF_LENGTH -> 11
    public const int QUE_POST_BUF_LENGTH = 11;
}

[System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)]
public struct QueSelectAddressType {

    /// WCHAR*
    [System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.LPWStr)]
    public string streetAddress;

    /// WCHAR*
    [System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.LPWStr)]
    public string city;

    /// WCHAR*
    [System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.LPWStr)]
    public string state;

    /// WCHAR*
    [System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.LPWStr)]
    public string country;

    /// WCHAR*
    [System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.LPWStr)]
    public string postalCode;
}

[System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential, CharSet=System.Runtime.InteropServices.CharSet.Unicode)]
public struct QueAddressType {

    /// WCHAR[51]
    [System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.ByValTStr, SizeConst=51)]
    public string streetAddress;

    /// WCHAR[51]
    [System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.ByValTStr, SizeConst=51)]
    public string city;

    /// WCHAR[51]
    [System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.ByValTStr, SizeConst=51)]
    public string state;

    /// WCHAR[51]
    [System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.ByValTStr, SizeConst=51)]
    public string country;

    /// WCHAR[12]
    [System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.ByValTStr, SizeConst=12)]
    public string postalCode;
}
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