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sdaiGetAggrByIndex

valueType argument to specify what type of data caller wants to get and value argument where the caller should provide a buffer, and the function will write the result to. Table 1 shows type of buffer the caller should provide depending on the valueType for sdaiGetAggrByIndex, and it works similarly for all get-functions. Note: with SDAI API it is impossible to check buffer type at compilation or execution time and this is responsibility of a caller to ensure that requested valueType is matching with the value argument, a mismatch will lead to unpredictable results. The Table 2 shows what valueType can be fulfilled depending on actual model data. If a get-function cannot get a value it will return 0, it may happen when model item is unset ($) or incompatible with requested valueType. To separate these cases you can use engiGetInstanceAttrType(BN), sdaiGetADBType and engiGetAggrType. On success get-function will return non-zero. More precisely, according to ISO 10303-24-2001 on success they return content of value argument (*value) for sdaiADB, sdaiAGGR, or sdaiINSTANCE or value argument itself for other types (it has no useful meaning for C#). 

Table 1 – Required value buffer depending on valueType (on the example of sdaiGetAggrByIndex but valid for all get-functions)

valueType               C/C++                                                               C#

sdaiINTEGER             int_t val;                                                          int_t val;
                        sdaiGetAggrByIndex (aggregate, index, sdaiINTEGER, &val);           ifcengine.sdaiGetAggrByIndex (aggregate, index, ifcengine.sdaiINTEGER, out val);

sdaiREAL or sdaiNUMBER  double val;                                                         double val;
                        sdaiGetAggrByIndex (aggregate, index, sdaiREAL, &val);              ifcengine.sdaiGetAggrByIndex (aggregate, index, ifcengine.sdaiREAL, out val);

sdaiBOOLEAN             SdaiBoolean val;                                                    bool val;
                        sdaiGetAggrByIndex (aggregate, index, sdaiBOOLEAN, &val);           ifcengine.sdaiGetAggrByIndex (aggregate, index, ifcengine.sdaiBOOLEAN, out val);

sdaiLOGICAL             const TCHAR* val;                                                   string val;
                        sdaiGetAggrByIndex (aggregate, index, sdaiLOGICAL, &val);           ifcengine.sdaiGetAggrByIndex (aggregate, index, ifcengine.sdaiLOGICAL, out val);

sdaiENUM                const TCHAR* val;                                                   string val;
                        sdaiGetAggrByIndex (aggregate, index, sdaiENUM, &val);              ifcengine.sdaiGetAggrByIndex (aggregate, index, ifcengine.sdaiENUM, out val);

sdaiBINARY              const TCHAR* val;                                                   string val;
                        sdaiGetAggrByIndex (aggregate, index, sdaiBINARY, &val);            ifcengine.sdaiGetAggrByIndex (aggregate, index, ifcengine.sdaiBINARY, out val);

sdaiSTRING              const char* val;                                                    string val;
                        sdaiGetAggrByIndex (aggregate, index, sdaiSTRING, &val);            ifcengine.sdaiGetAggrByIndex (aggregate, index, ifcengine.sdaiSTRING, out val);

sdaiUNICODE             const wchar_t* val;                                                 string val;
                        sdaiGetAggrByIndex (aggregate, index, sdaiUNICODE, &val);           ifcengine.sdaiGetAggrByIndex (aggregate, index, ifcengine.sdaiUNICODE, out val);

sdaiEXPRESSSTRING       const char* val;                                                    string val;
                        sdaiGetAggrByIndex (aggregate, index, sdaiEXPRESSSTRING, &val);     ifcengine.sdaiGetAggrByIndex (aggregate, index, ifcengine.sdaiEXPRESSSTRING, out val);

sdaiINSTANCE            SdaiInstance val;                                                   int_t val;
                        sdaiGetAggrByIndex (aggregate, index, sdaiINSTANCE, &val);          ifcengine.sdaiGetAggrByIndex (aggregate, index, ifcengine.sdaiINSTANCE, out val);

sdaiAGGR                SdaiAggr aggr;                                                      int_t aggr;
                        sdaiGetAggrByIndex (aggregate, index, sdaiAGGR, &aggr);             ifcengine.sdaiGetAggrByIndex (aggregate, index, ifcengine.sdaiAGGR, out aggr);

sdaiADB                 SdaiADB adb = sdaiCreateEmptyADB();                                 int_t adb = 0;  //  it is important to initialize
                        sdaiGetAggrByIndex (aggregate, index, sdaiADB, adb);                ifcengine.sdaiGetAggrByIndex (aggregate, index, ifcengine.sdaiADB, out adb);        
                        sdaiDeleteADB (adb);

                        SdaiADB adb = nullptr;  //  it is important to initialize
                        sdaiGetAggrByIndex (aggregate, index, sdaiADB, &adb);
TCHAR is “char” or “wchar_t” depending on setStringUnicode. (Non-standard behavior) sdaiLOGICAL behaves differently from ISO 10303-24-2001: it expects char* while standard declares int_t. (Non-standard extension) sdiADB in C++ has an option to work without sdaiCreateEmptyADB and sdaiDeleteADB as shown in the table. 
Table 2 - valueType can be requested depending on actual model data.

valueType       Works for following values in the model
                  integer      real     .T. or .F.     .U.      other enum    binary      string     instance      list      $ (empty)
sdaiINTEGER         Yes         Yes *        .           .           .           .           .           .           .           .
sdaiREAL            Yes         Yes          .           .           .           .           .           .           .           .
sdaiNUMBER          Yes         Yes          .           .           .           .           .           .           .           .
sdaiBOOLEAN          .           .          Yes          .           .           .           .           .           .           .
sdaiLOGICAL          .           .          Yes         Yes          .           .           .           .           .           .
sdaiENUM             .           .          Yes         Yes         Yes          .           .           .           .           .
sdaiBINARY           .           .           .           .           .          Yes          .           .           .           .
sdaiSTRING          Yes         Yes         Yes         Yes         Yes         Yes         Yes          .           .           .
sdaiUNICODE         Yes         Yes         Yes         Yes         Yes         Yes         Yes          .           .           .
sdaiEXPRESSSTRING   Yes         Yes         Yes         Yes         Yes         Yes         Yes          .           .           .
sdaiINSTANCE         .           .           .           .           .           .           .          Yes          .           .
sdaiAGGR             .           .           .           .           .           .           .           .          Yes          .
sdaiADB             Yes         Yes         Yes         Yes         Yes         Yes         Yes         Yes         Yes          .
Note: sdaiGetAttr, stdaiGetAttrBN, engiGetElement will success with any model data, except non-set($) (Non-standard extensions) sdaiGetADBValue: sdaiADB is allowed and will success when sdaiGetADBTypePath is not NULL, returning ABD value has type path element removed.

Syntax

C++ 32 bit
C++ 64 bit
C# 32 bit
C# 64 bit
public const string ifcenginedll = @"ifcengine.dll";

[DllImport(IFCEngineDLL, EntryPoint = "sdaiGetAggrByIndex")]
public static extern Int64 sdaiGetAggrByIndex(int_t aggregate, int_t index, int_t valueType, out bool value);

[DllImport(IFCEngineDLL, EntryPoint = "sdaiGetAggrByIndex")]
public static extern Int64 sdaiGetAggrByIndex(int_t aggregate, int_t index, int_t valueType, out int_t value);

[DllImport(IFCEngineDLL, EntryPoint = "sdaiGetAggrByIndex")]
public static extern Int64 sdaiGetAggrByIndex(int_t aggregate, int_t index, int_t valueType, out double value);

[DllImport(IFCEngineDLL, EntryPoint = "sdaiGetAggrByIndex")]
public static extern Int64 sdaiGetAggrByIndex(int_t aggregate, int_t index, int_t valueType, out IntPtr value);

public static Int64 sdaiGetAggrByIndex(int_t aggregate, int_t index, int_t valueType, out string value)
        {
            value = null;
            valueType = getStringType(valueType);
            if (valueType != 0)
            {
                IntPtr ptr = IntPtr.Zero;
                var ret = sdaiGetAggrByIndex(aggregate, index, valueType, out ptr);
                if (ret != 0 && ptr != IntPtr.Zero)
                {
                    value = marshalPtrToString(valueType, ptr);
                    return ret;
                }
            }
            return 0;
        }

Property aggregate

Size: 64 bit / 8 byte (reference)
...

Property index

Size: 64 bit / 8 byte (value)
...

Property valueType

Size: 64 bit / 8 byte (value)
...

Property value

Size: 64 bit / 8 byte (reference)
...