Dynamic Link Library Usage in Excel/Visual Basic, here is how it works:
 

1. FORTRAN 90 based
2. C/C++ based

We illustrate how a formula implemented in FORTRAN 90 and compiled as a dynamic link library (DLL) can be used in Microsoft Excel/Visual Basic.

Take the Formula WY_VANILLA from the Financial Functions Library as given. The resulting DLL must be copied into the system directory of your harddisk. Afterwards start the excel file in which you intend to use the function and type the following command into the visual basic editor:

Declare Function WY_VANILLA Lib "FFLIB.DLL" (ByRef spot As Double, ByRef strike As Double, ByRef vol As Double, _
                                           ByRef rd As Double, ByRef rf As Double, ByRef tau As Double, _
                                           ByRef phi As Long, ByRef convention As Long, _
                                           ByRef quotation As Long, ByRef greek As Long) As Double

This method also works similar for C++ source code and helps improving the performance of your spreadsheet significantly. Proceed as follows.

1. In the visual studio open a new project called “c2vbtest” as a WIN32 dynamic-link-library.
2. Choose the menu Project\Add to Project\files
3. Add the three files c2vbtest.cpp, c2vbtest.def and xlcall.h.
4. Compile c2vbtest.cpp
5. Build c2vbtest.dll
6. Use the Windows Explorer to find the dynamic-link-library „c2vbtest.dll“ in the debug folder of your project. Note that it is not uncommon for Windows Explorer to be set up so that *.dll files are not displayed. To change the setting so that „c2vbtest.dll“ can be seen, click View\Options\Show all files.Click it once with the right mouse button and choose quick view
7. In the export table the function savitri shows.
8. Copy c2vbtest.dll into the folder WINNT\system32. An alternative is to store the dll somewhere else and enter the complete path in the visual basic declare command:
9. Declare Function savitri Lib " C:\MyProjects\c2vbtest\debug\c2vbtest.dll " (ByVal x As Double) As Double
10. Open a new c2vbtest.xls and declare the functions and subs in a visual basic module.

On the usage of

__declspec ( dllexport ) double WINAPI func(x as double) { return x*3; }

This is supposed to be an alternative to using .def files. However, the name of the function (here func) appears very distorted in the quickview of the .dll. I recommend using .def files to make sure the exported functions can be used under the intended name.
 

For using arrays see http://support.microsoft.com/support/kb/articles/Q171/5/83.ASP

Another resource (in French) for xlls and subs is http://longre.free.fr/pages/prog/api-c.htm

Enter this in the file c2vbtest.def and include it in  your project

LIBRARY C2VBTEST

DESCRIPTION 'C 2 VB tutorial'

EXETYPE WINDOWS
 
 

HEAPSIZE  8192

EXPORTS
 savitri
 ganesh
 shiva
 durga
 saraswati

This is the c code in the file c2vbtest.cpp:
 

#include <windows.h>
#include <oleauto.h>
#include "xlcall.h"
 

double WINAPI savitri(double x)
{
 return x * 2;
}
 

__declspec( dllexport ) double WINAPI  ganesh(double x)
{
 return x * 3;
}

double WINAPI shiva(double *x)
{
 return x[0] * 2. + x[1] * 3.;
}

void WINAPI durga()
{
 int i;
 i=2;
}

void WINAPI saraswati(double x, bool *x_is_positive)
{ if (x>0.)
 {
  *x_is_positive = true;
 }
 else
 {
  *x_is_positive = false;
 }
}

This header file must be included in your project: xlcall.h
 

/*
**  Microsoft Excel Developer's Toolkit
**  Version 8.0
**
**  File:           INCLUDE\XLCALL.H
**  Description:    Header file for for Microsoft Excel callbacks
**  Platform:       Microsoft Windows
**
**  This file defines the constants and
**  data types which are used in the
**  Microsoft Excel C API. Include
**  <windows.h> before you include this.
**
*/

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */

/*
** XLREF structure
**
** Describes a single rectangular reference
*/

typedef struct xlref
{
    WORD rwFirst;
    WORD rwLast;
    BYTE colFirst;
    BYTE colLast;
} XLREF, FAR *LPXLREF;
 

/*
** XLMREF structure
**
** Describes multiple rectangular references.
** This is a variable size structure, default
** size is 1 reference.
*/

typedef struct xlmref
{
    WORD count;
    XLREF reftbl[1];                        /* actually reftbl[count] */
} XLMREF, FAR *LPXLMREF;
 

/*
** XLOPER structure
**
** Excel's fundamental data type: can hold data
** of any type. Use "R" as the argument type in the
** REGISTER function.
**/

typedef struct xloper
{
    union
    {
        double num;                     /* xltypeNum */
        LPSTR str;                      /* xltypeStr */
        WORD bool;                      /* xltypeBool */
        WORD err;                       /* xltypeErr */
        short int w;                    /* xltypeInt */
        struct
        {
            WORD count;                 /* always = 1 */
            XLREF ref;
        } sref;                         /* xltypeSRef */
        struct
        {
            XLMREF far *lpmref;
            DWORD idSheet;
        } mref;                         /* xltypeRef */
        struct
        {
            struct xloper far *lparray;
            WORD rows;
            WORD columns;
        } array;                        /* xltypeMulti */
        struct
        {
            union
            {
                short int level;        /* xlflowRestart */
                short int tbctrl;       /* xlflowPause */
                DWORD idSheet;          /* xlflowGoto */
            } valflow;
            WORD rw;                    /* xlflowGoto */
            BYTE col;                   /* xlflowGoto */
            BYTE xlflow;
        } flow;                         /* xltypeFlow */
        struct
        {
            union
            {
                BYTE far *lpbData;      /* data passed to XL */
                HANDLE hdata;           /* data returned from XL */
            } h;
            long cbData;
        } bigdata;                      /* xltypeBigData */
    } val;
    WORD xltype;
} XLOPER, FAR *LPXLOPER;
 

/*
** XLOPER data types
**
** Used for xltype field of XLOPER structure
*/

#define xltypeNum        0x0001
#define xltypeStr        0x0002
#define xltypeBool       0x0004
#define xltypeRef        0x0008
#define xltypeErr        0x0010
#define xltypeFlow       0x0020
#define xltypeMulti      0x0040
#define xltypeMissing    0x0080
#define xltypeNil        0x0100
#define xltypeSRef       0x0400
#define xltypeInt        0x0800
#define xlbitXLFree      0x1000
#define xlbitDLLFree     0x4000

#define xltypeBigData    (xltypeStr | xltypeInt)
 

/*
** Error codes
**
** Used for val.err field of XLOPER structure
** when constructing error XLOPERs
*/

#define xlerrNull    0
#define xlerrDiv0    7
#define xlerrValue   15
#define xlerrRef     23
#define xlerrName    29
#define xlerrNum     36
#define xlerrNA      42
 

/*
** Flow data types
**
** Used for val.flow.xlflow field of XLOPER structure
** when constructing flow-control XLOPERs
**/

#define xlflowHalt       1
#define xlflowGoto       2
#define xlflowRestart    8
#define xlflowPause      16
#define xlflowResume     64
 

/*
** Function prototypes
*/

int far _cdecl Excel4(int xlfn, LPXLOPER operRes, int count,... );
/* followed by count LPXLOPERs */

int far pascal Excel4v(int xlfn, LPXLOPER operRes, int count, LPXLOPER far opers[]);
int far pascal XLCallVer(void);
 

/*
** Return codes
**
** These values can be returned from Excel4() or Excel4v().
*/

#define xlretSuccess    0     /* success */
#define xlretAbort      1     /* macro halted */
#define xlretInvXlfn    2     /* invalid function number */
#define xlretInvCount   4     /* invalid number of arguments */
#define xlretInvXloper  8     /* invalid OPER structure */
#define xlretStackOvfl  16    /* stack overflow */
#define xlretFailed     32    /* command failed */
#define xlretUncalced   64    /* uncalced cell */
 

/*
** Function number bits
*/

#define xlCommand    0x8000
#define xlSpecial    0x4000
#define xlIntl       0x2000
#define xlPrompt     0x1000
 

/*
** Auxiliary function numbers
**
** These functions are available only from the C API,
** not from the Excel macro language.
*/

#define xlFree             (0  | xlSpecial)
#define xlStack            (1  | xlSpecial)
#define xlCoerce           (2  | xlSpecial)
#define xlSet              (3  | xlSpecial)
#define xlSheetId          (4  | xlSpecial)
#define xlSheetNm          (5  | xlSpecial)
#define xlAbort            (6  | xlSpecial)
#define xlGetInst          (7  | xlSpecial)
#define xlGetHwnd          (8  | xlSpecial)
#define xlGetName          (9  | xlSpecial)
#define xlEnableXLMsgs     (10 | xlSpecial)
#define xlDisableXLMsgs    (11 | xlSpecial)
#define xlDefineBinaryName (12 | xlSpecial)
#define xlGetBinaryName    (13 | xlSpecial)
 

/*
** User defined function
**
** First argument should be a function reference.
*/

#define xlUDF      255
 

/*
** Built-in Functions and Command Equivalents
*/
 

/* Excel function numbers */
#define xlfCount 0
#define xlfIsna 2
#define xlfIserror 3
#define xlfSum 4
#define xlfAverage 5
#define xlfMin 6
#define xlfMax 7
#define xlfRow 8
#define xlfColumn 9
#define xlfNa 10
#define xlfNpv 11
#define xlfStdev 12
#define xlfDollar 13
#define xlfFixed 14
#define xlfSin 15
#define xlfCos 16
#define xlfTan 17
#define xlfAtan 18
#define xlfPi 19
#define xlfSqrt 20
#define xlfExp 21
#define xlfLn 22
#define xlfLog10 23
#define xlfAbs 24
#define xlfInt 25
#define xlfSign 26
#define xlfRound 27
#define xlfLookup 28
#define xlfIndex 29
#define xlfRept 30
#define xlfMid 31
#define xlfLen 32
#define xlfValue 33
#define xlfTrue 34
#define xlfFalse 35
#define xlfAnd 36
#define xlfOr 37
#define xlfNot 38
#define xlfMod 39
#define xlfDcount 40
#define xlfDsum 41
#define xlfDaverage 42
#define xlfDmin 43
#define xlfDmax 44
#define xlfDstdev 45
#define xlfVar 46
#define xlfDvar 47
#define xlfText 48
#define xlfLinest 49
#define xlfTrend 50
#define xlfLogest 51
#define xlfGrowth 52
#define xlfGoto 53
#define xlfHalt 54
#define xlfPv 56
#define xlfFv 57
#define xlfNper 58
#define xlfPmt 59
#define xlfRate 60
#define xlfMirr 61
#define xlfIrr 62
#define xlfRand 63
#define xlfMatch 64
#define xlfDate 65
#define xlfTime 66
#define xlfDay 67
#define xlfMonth 68
#define xlfYear 69
#define xlfWeekday 70
#define xlfHour 71
#define xlfMinute 72
#define xlfSecond 73
#define xlfNow 74
#define xlfAreas 75
#define xlfRows 76
#define xlfColumns 77
#define xlfOffset 78
#define xlfAbsref 79
#define xlfRelref 80
#define xlfArgument 81
#define xlfSearch 82
#define xlfTranspose 83
#define xlfError 84
#define xlfStep 85
#define xlfType 86
#define xlfEcho 87
#define xlfSetName 88
#define xlfCaller 89
#define xlfDeref 90
#define xlfWindows 91
#define xlfSeries 92
#define xlfDocuments 93
#define xlfActiveCell 94
#define xlfSelection 95
#define xlfResult 96
#define xlfAtan2 97
#define xlfAsin 98
#define xlfAcos 99
#define xlfChoose 100
#define xlfHlookup 101
#define xlfVlookup 102
#define xlfLinks 103
#define xlfInput 104
#define xlfIsref 105
#define xlfGetFormula 106
#define xlfGetName 107
#define xlfSetValue 108
#define xlfLog 109
#define xlfExec 110
#define xlfChar 111
#define xlfLower 112
#define xlfUpper 113
#define xlfProper 114
#define xlfLeft 115
#define xlfRight 116
#define xlfExact 117
#define xlfTrim 118
#define xlfReplace 119
#define xlfSubstitute 120
#define xlfCode 121
#define xlfNames 122
#define xlfDirectory 123
#define xlfFind 124
#define xlfCell 125
#define xlfIserr 126
#define xlfIstext 127
#define xlfIsnumber 128
#define xlfIsblank 129
#define xlfT 130
#define xlfN 131
#define xlfFopen 132
#define xlfFclose 133
#define xlfFsize 134
#define xlfFreadln 135
#define xlfFread 136
#define xlfFwriteln 137
#define xlfFwrite 138
#define xlfFpos 139
#define xlfDatevalue 140
#define xlfTimevalue 141
#define xlfSln 142
#define xlfSyd 143
#define xlfDdb 144
#define xlfGetDef 145
#define xlfReftext 146
#define xlfTextref 147
#define xlfIndirect 148
#define xlfRegister 149
#define xlfCall 150
#define xlfAddBar 151
#define xlfAddMenu 152
#define xlfAddCommand 153
#define xlfEnableCommand 154
#define xlfCheckCommand 155
#define xlfRenameCommand 156
#define xlfShowBar 157
#define xlfDeleteMenu 158
#define xlfDeleteCommand 159
#define xlfGetChartItem 160
#define xlfDialogBox 161
#define xlfClean 162
#define xlfMdeterm 163
#define xlfMinverse 164
#define xlfMmult 165
#define xlfFiles 166
#define xlfIpmt 167
#define xlfPpmt 168
#define xlfCounta 169
#define xlfCancelKey 170
#define xlfInitiate 175
#define xlfRequest 176
#define xlfPoke 177
#define xlfExecute 178
#define xlfTerminate 179
#define xlfRestart 180
#define xlfHelp 181
#define xlfGetBar 182
#define xlfProduct 183
#define xlfFact 184
#define xlfGetCell 185
#define xlfGetWorkspace 186
#define xlfGetWindow 187
#define xlfGetDocument 188
#define xlfDproduct 189
#define xlfIsnontext 190
#define xlfGetNote 191
#define xlfNote 192
#define xlfStdevp 193
#define xlfVarp 194
#define xlfDstdevp 195
#define xlfDvarp 196
#define xlfTrunc 197
#define xlfIslogical 198
#define xlfDcounta 199
#define xlfDeleteBar 200
#define xlfUnregister 201
#define xlfUsdollar 204
#define xlfFindb 205
#define xlfSearchb 206
#define xlfReplaceb 207
#define xlfLeftb 208
#define xlfRightb 209
#define xlfMidb 210
#define xlfLenb 211
#define xlfRoundup 212
#define xlfRounddown 213
#define xlfAsc 214
#define xlfDbcs 215
#define xlfRank 216
#define xlfAddress 219
#define xlfDays360 220
#define xlfToday 221
#define xlfVdb 222
#define xlfMedian 227
#define xlfSumproduct 228
#define xlfSinh 229
#define xlfCosh 230
#define xlfTanh 231
#define xlfAsinh 232
#define xlfAcosh 233
#define xlfAtanh 234
#define xlfDget 235
#define xlfCreateObject 236
#define xlfVolatile 237
#define xlfLastError 238
#define xlfCustomUndo 239
#define xlfCustomRepeat 240
#define xlfFormulaConvert 241
#define xlfGetLinkInfo 242
#define xlfTextBox 243
#define xlfInfo 244
#define xlfGroup 245
#define xlfGetObject 246
#define xlfDb 247
#define xlfPause 248
#define xlfResume 251
#define xlfFrequency 252
#define xlfAddToolbar 253
#define xlfDeleteToolbar 254
#define xlfResetToolbar 256
#define xlfEvaluate 257
#define xlfGetToolbar 258
#define xlfGetTool 259
#define xlfSpellingCheck 260
#define xlfErrorType 261
#define xlfAppTitle 262
#define xlfWindowTitle 263
#define xlfSaveToolbar 264
#define xlfEnableTool 265
#define xlfPressTool 266
#define xlfRegisterId 267
#define xlfGetWorkbook 268
#define xlfAvedev 269
#define xlfBetadist 270
#define xlfGammaln 271
#define xlfBetainv 272
#define xlfBinomdist 273
#define xlfChidist 274
#define xlfChiinv 275
#define xlfCombin 276
#define xlfConfidence 277
#define xlfCritbinom 278
#define xlfEven 279
#define xlfExpondist 280
#define xlfFdist 281
#define xlfFinv 282
#define xlfFisher 283
#define xlfFisherinv 284
#define xlfFloor 285
#define xlfGammadist 286
#define xlfGammainv 287
#define xlfCeiling 288
#define xlfHypgeomdist 289
#define xlfLognormdist 290
#define xlfLoginv 291
#define xlfNegbinomdist 292
#define xlfNormdist 293
#define xlfNormsdist 294
#define xlfNorminv 295
#define xlfNormsinv 296
#define xlfStandardize 297
#define xlfOdd 298
#define xlfPermut 299
#define xlfPoisson 300
#define xlfTdist 301
#define xlfWeibull 302
#define xlfSumxmy2 303
#define xlfSumx2my2 304
#define xlfSumx2py2 305
#define xlfChitest 306
#define xlfCorrel 307
#define xlfCovar 308
#define xlfForecast 309
#define xlfFtest 310
#define xlfIntercept 311
#define xlfPearson 312
#define xlfRsq 313
#define xlfSteyx 314
#define xlfSlope 315
#define xlfTtest 316
#define xlfProb 317
#define xlfDevsq 318
#define xlfGeomean 319
#define xlfHarmean 320
#define xlfSumsq 321
#define xlfKurt 322
#define xlfSkew 323
#define xlfZtest 324
#define xlfLarge 325
#define xlfSmall 326
#define xlfQuartile 327
#define xlfPercentile 328
#define xlfPercentrank 329
#define xlfMode 330
#define xlfTrimmean 331
#define xlfTinv 332
#define xlfMovieCommand 334
#define xlfGetMovie 335
#define xlfConcatenate 336
#define xlfPower 337
#define xlfPivotAddData 338
#define xlfGetPivotTable 339
#define xlfGetPivotField 340
#define xlfGetPivotItem 341
#define xlfRadians 342
#define xlfDegrees 343
#define xlfSubtotal 344
#define xlfSumif 345
#define xlfCountif 346
#define xlfCountblank 347
#define xlfScenarioGet 348
#define xlfOptionsListsGet 349
#define xlfIspmt 350
#define xlfDatedif 351
#define xlfDatestring 352
#define xlfNumberstring 353
#define xlfRoman 354
#define xlfOpenDialog 355
#define xlfSaveDialog 356
#define xlfViewGet 357
#define xlfGetPivotData 358
#define xlfHyperlink 359
#define xlfPhonetic 360
#define xlfAverageA 361
#define xlfMaxA 362
#define xlfMinA 363
#define xlfStDevPA 364
#define xlfVarPA 365
#define xlfStDevA 366
#define xlfVarA 367

/* Excel command numbers */
#define xlcBeep (0 | xlCommand)
#define xlcOpen (1 | xlCommand)
#define xlcOpenLinks (2 | xlCommand)
#define xlcCloseAll (3 | xlCommand)
#define xlcSave (4 | xlCommand)
#define xlcSaveAs (5 | xlCommand)
#define xlcFileDelete (6 | xlCommand)
#define xlcPageSetup (7 | xlCommand)
#define xlcPrint (8 | xlCommand)
#define xlcPrinterSetup (9 | xlCommand)
#define xlcQuit (10 | xlCommand)
#define xlcNewWindow (11 | xlCommand)
#define xlcArrangeAll (12 | xlCommand)
#define xlcWindowSize (13 | xlCommand)
#define xlcWindowMove (14 | xlCommand)
#define xlcFull (15 | xlCommand)
#define xlcClose (16 | xlCommand)
#define xlcRun (17 | xlCommand)
#define xlcSetPrintArea (22 | xlCommand)
#define xlcSetPrintTitles (23 | xlCommand)
#define xlcSetPageBreak (24 | xlCommand)
#define xlcRemovePageBreak (25 | xlCommand)
#define xlcFont (26 | xlCommand)
#define xlcDisplay (27 | xlCommand)
#define xlcProtectDocument (28 | xlCommand)
#define xlcPrecision (29 | xlCommand)
#define xlcA1R1c1 (30 | xlCommand)
#define xlcCalculateNow (31 | xlCommand)
#define xlcCalculation (32 | xlCommand)
#define xlcDataFind (34 | xlCommand)
#define xlcExtract (35 | xlCommand)
#define xlcDataDelete (36 | xlCommand)
#define xlcSetDatabase (37 | xlCommand)
#define xlcSetCriteria (38 | xlCommand)
#define xlcSort (39 | xlCommand)
#define xlcDataSeries (40 | xlCommand)
#define xlcTable (41 | xlCommand)
#define xlcFormatNumber (42 | xlCommand)
#define xlcAlignment (43 | xlCommand)
#define xlcStyle (44 | xlCommand)
#define xlcBorder (45 | xlCommand)
#define xlcCellProtection (46 | xlCommand)
#define xlcColumnWidth (47 | xlCommand)
#define xlcUndo (48 | xlCommand)
#define xlcCut (49 | xlCommand)
#define xlcCopy (50 | xlCommand)
#define xlcPaste (51 | xlCommand)
#define xlcClear (52 | xlCommand)
#define xlcPasteSpecial (53 | xlCommand)
#define xlcEditDelete (54 | xlCommand)
#define xlcInsert (55 | xlCommand)
#define xlcFillRight (56 | xlCommand)
#define xlcFillDown (57 | xlCommand)
#define xlcDefineName (61 | xlCommand)
#define xlcCreateNames (62 | xlCommand)
#define xlcFormulaGoto (63 | xlCommand)
#define xlcFormulaFind (64 | xlCommand)
#define xlcSelectLastCell (65 | xlCommand)
#define xlcShowActiveCell (66 | xlCommand)
#define xlcGalleryArea (67 | xlCommand)
#define xlcGalleryBar (68 | xlCommand)
#define xlcGalleryColumn (69 | xlCommand)
#define xlcGalleryLine (70 | xlCommand)
#define xlcGalleryPie (71 | xlCommand)
#define xlcGalleryScatter (72 | xlCommand)
#define xlcCombination (73 | xlCommand)
#define xlcPreferred (74 | xlCommand)
#define xlcAddOverlay (75 | xlCommand)
#define xlcGridlines (76 | xlCommand)
#define xlcSetPreferred (77 | xlCommand)
#define xlcAxes (78 | xlCommand)
#define xlcLegend (79 | xlCommand)
#define xlcAttachText (80 | xlCommand)
#define xlcAddArrow (81 | xlCommand)
#define xlcSelectChart (82 | xlCommand)
#define xlcSelectPlotArea (83 | xlCommand)
#define xlcPatterns (84 | xlCommand)
#define xlcMainChart (85 | xlCommand)
#define xlcOverlay (86 | xlCommand)
#define xlcScale (87 | xlCommand)
#define xlcFormatLegend (88 | xlCommand)
#define xlcFormatText (89 | xlCommand)
#define xlcEditRepeat (90 | xlCommand)
#define xlcParse (91 | xlCommand)
#define xlcJustify (92 | xlCommand)
#define xlcHide (93 | xlCommand)
#define xlcUnhide (94 | xlCommand)
#define xlcWorkspace (95 | xlCommand)
#define xlcFormula (96 | xlCommand)
#define xlcFormulaFill (97 | xlCommand)
#define xlcFormulaArray (98 | xlCommand)
#define xlcDataFindNext (99 | xlCommand)
#define xlcDataFindPrev (100 | xlCommand)
#define xlcFormulaFindNext (101 | xlCommand)
#define xlcFormulaFindPrev (102 | xlCommand)
#define xlcActivate (103 | xlCommand)
#define xlcActivateNext (104 | xlCommand)
#define xlcActivatePrev (105 | xlCommand)
#define xlcUnlockedNext (106 | xlCommand)
#define xlcUnlockedPrev (107 | xlCommand)
#define xlcCopyPicture (108 | xlCommand)
#define xlcSelect (109 | xlCommand)
#define xlcDeleteName (110 | xlCommand)
#define xlcDeleteFormat (111 | xlCommand)
#define xlcVline (112 | xlCommand)
#define xlcHline (113 | xlCommand)
#define xlcVpage (114 | xlCommand)
#define xlcHpage (115 | xlCommand)
#define xlcVscroll (116 | xlCommand)
#define xlcHscroll (117 | xlCommand)
#define xlcAlert (118 | xlCommand)
#define xlcNew (119 | xlCommand)
#define xlcCancelCopy (120 | xlCommand)
#define xlcShowClipboard (121 | xlCommand)
#define xlcMessage (122 | xlCommand)
#define xlcPasteLink (124 | xlCommand)
#define xlcAppActivate (125 | xlCommand)
#define xlcDeleteArrow (126 | xlCommand)
#define xlcRowHeight (127 | xlCommand)
#define xlcFormatMove (128 | xlCommand)
#define xlcFormatSize (129 | xlCommand)
#define xlcFormulaReplace (130 | xlCommand)
#define xlcSendKeys (131 | xlCommand)
#define xlcSelectSpecial (132 | xlCommand)
#define xlcApplyNames (133 | xlCommand)
#define xlcReplaceFont (134 | xlCommand)
#define xlcFreezePanes (135 | xlCommand)
#define xlcShowInfo (136 | xlCommand)
#define xlcSplit (137 | xlCommand)
#define xlcOnWindow (138 | xlCommand)
#define xlcOnData (139 | xlCommand)
#define xlcDisableInput (140 | xlCommand)
#define xlcEcho (141 | xlCommand)
#define xlcOutline (142 | xlCommand)
#define xlcListNames (143 | xlCommand)
#define xlcFileClose (144 | xlCommand)
#define xlcSaveWorkbook (145 | xlCommand)
#define xlcDataForm (146 | xlCommand)
#define xlcCopyChart (147 | xlCommand)
#define xlcOnTime (148 | xlCommand)
#define xlcWait (149 | xlCommand)
#define xlcFormatFont (150 | xlCommand)
#define xlcFillUp (151 | xlCommand)
#define xlcFillLeft (152 | xlCommand)
#define xlcDeleteOverlay (153 | xlCommand)
#define xlcNote (154 | xlCommand)
#define xlcShortMenus (155 | xlCommand)
#define xlcSetUpdateStatus (159 | xlCommand)
#define xlcColorPalette (161 | xlCommand)
#define xlcDeleteStyle (162 | xlCommand)
#define xlcWindowRestore (163 | xlCommand)
#define xlcWindowMaximize (164 | xlCommand)
#define xlcError (165 | xlCommand)
#define xlcChangeLink (166 | xlCommand)
#define xlcCalculateDocument (167 | xlCommand)
#define xlcOnKey (168 | xlCommand)
#define xlcAppRestore (169 | xlCommand)
#define xlcAppMove (170 | xlCommand)
#define xlcAppSize (171 | xlCommand)
#define xlcAppMinimize (172 | xlCommand)
#define xlcAppMaximize (173 | xlCommand)
#define xlcBringToFront (174 | xlCommand)
#define xlcSendToBack (175 | xlCommand)
#define xlcMainChartType (185 | xlCommand)
#define xlcOverlayChartType (186 | xlCommand)
#define xlcSelectEnd (187 | xlCommand)
#define xlcOpenMail (188 | xlCommand)
#define xlcSendMail (189 | xlCommand)
#define xlcStandardFont (190 | xlCommand)
#define xlcConsolidate (191 | xlCommand)
#define xlcSortSpecial (192 | xlCommand)
#define xlcGallery3dArea (193 | xlCommand)
#define xlcGallery3dColumn (194 | xlCommand)
#define xlcGallery3dLine (195 | xlCommand)
#define xlcGallery3dPie (196 | xlCommand)
#define xlcView3d (197 | xlCommand)
#define xlcGoalSeek (198 | xlCommand)
#define xlcWorkgroup (199 | xlCommand)
#define xlcFillGroup (200 | xlCommand)
#define xlcUpdateLink (201 | xlCommand)
#define xlcPromote (202 | xlCommand)
#define xlcDemote (203 | xlCommand)
#define xlcShowDetail (204 | xlCommand)
#define xlcUngroup (206 | xlCommand)
#define xlcObjectProperties (207 | xlCommand)
#define xlcSaveNewObject (208 | xlCommand)
#define xlcShare (209 | xlCommand)
#define xlcShareName (210 | xlCommand)
#define xlcDuplicate (211 | xlCommand)
#define xlcApplyStyle (212 | xlCommand)
#define xlcAssignToObject (213 | xlCommand)
#define xlcObjectProtection (214 | xlCommand)
#define xlcHideObject (215 | xlCommand)
#define xlcSetExtract (216 | xlCommand)
#define xlcCreatePublisher (217 | xlCommand)
#define xlcSubscribeTo (218 | xlCommand)
#define xlcAttributes (219 | xlCommand)
#define xlcShowToolbar (220 | xlCommand)
#define xlcPrintPreview (222 | xlCommand)
#define xlcEditColor (223 | xlCommand)
#define xlcShowLevels (224 | xlCommand)
#define xlcFormatMain (225 | xlCommand)
#define xlcFormatOverlay (226 | xlCommand)
#define xlcOnRecalc (227 | xlCommand)
#define xlcEditSeries (228 | xlCommand)
#define xlcDefineStyle (229 | xlCommand)
#define xlcLinePrint (240 | xlCommand)
#define xlcEnterData (243 | xlCommand)
#define xlcGalleryRadar (249 | xlCommand)
#define xlcMergeStyles (250 | xlCommand)
#define xlcEditionOptions (251 | xlCommand)
#define xlcPastePicture (252 | xlCommand)
#define xlcPastePictureLink (253 | xlCommand)
#define xlcSpelling (254 | xlCommand)
#define xlcZoom (256 | xlCommand)
#define xlcResume (258 | xlCommand)
#define xlcInsertObject (259 | xlCommand)
#define xlcWindowMinimize (260 | xlCommand)
#define xlcSize (261 | xlCommand)
#define xlcMove (262 | xlCommand)
#define xlcSoundNote (265 | xlCommand)
#define xlcSoundPlay (266 | xlCommand)
#define xlcFormatShape (267 | xlCommand)
#define xlcExtendPolygon (268 | xlCommand)
#define xlcFormatAuto (269 | xlCommand)
#define xlcGallery3dBar (272 | xlCommand)
#define xlcGallery3dSurface (273 | xlCommand)
#define xlcFillAuto (274 | xlCommand)
#define xlcCustomizeToolbar (276 | xlCommand)
#define xlcAddTool (277 | xlCommand)
#define xlcEditObject (278 | xlCommand)
#define xlcOnDoubleclick (279 | xlCommand)
#define xlcOnEntry (280 | xlCommand)
#define xlcWorkbookAdd (281 | xlCommand)
#define xlcWorkbookMove (282 | xlCommand)
#define xlcWorkbookCopy (283 | xlCommand)
#define xlcWorkbookOptions (284 | xlCommand)
#define xlcSaveWorkspace (285 | xlCommand)
#define xlcChartWizard (288 | xlCommand)
#define xlcDeleteTool (289 | xlCommand)
#define xlcMoveTool (290 | xlCommand)
#define xlcWorkbookSelect (291 | xlCommand)
#define xlcWorkbookActivate (292 | xlCommand)
#define xlcAssignToTool (293 | xlCommand)
#define xlcCopyTool (295 | xlCommand)
#define xlcResetTool (296 | xlCommand)
#define xlcConstrainNumeric (297 | xlCommand)
#define xlcPasteTool (298 | xlCommand)
#define xlcPlacement (300 | xlCommand)
#define xlcFillWorkgroup (301 | xlCommand)
#define xlcWorkbookNew (302 | xlCommand)
#define xlcScenarioCells (305 | xlCommand)
#define xlcScenarioDelete (306 | xlCommand)
#define xlcScenarioAdd (307 | xlCommand)
#define xlcScenarioEdit (308 | xlCommand)
#define xlcScenarioShow (309 | xlCommand)
#define xlcScenarioShowNext (310 | xlCommand)
#define xlcScenarioSummary (311 | xlCommand)
#define xlcPivotTableWizard (312 | xlCommand)
#define xlcPivotFieldProperties (313 | xlCommand)
#define xlcPivotField (314 | xlCommand)
#define xlcPivotItem (315 | xlCommand)
#define xlcPivotAddFields (316 | xlCommand)
#define xlcOptionsCalculation (318 | xlCommand)
#define xlcOptionsEdit (319 | xlCommand)
#define xlcOptionsView (320 | xlCommand)
#define xlcAddinManager (321 | xlCommand)
#define xlcMenuEditor (322 | xlCommand)
#define xlcAttachToolbars (323 | xlCommand)
#define xlcVbaReset (324 | xlCommand)
#define xlcOptionsChart (325 | xlCommand)
#define xlcStart (326 | xlCommand)
#define xlcVbaEnd (327 | xlCommand)
#define xlcVbaInsertFile (328 | xlCommand)
#define xlcVbaProcedureDefinition (330 | xlCommand)
#define xlcVbaReferences (331 | xlCommand)
#define xlcVbaStepInto (332 | xlCommand)
#define xlcVbaStepOver (333 | xlCommand)
#define xlcVbaToggleBreakpoint (334 | xlCommand)
#define xlcVbaClearBreakpoints (335 | xlCommand)
#define xlcRoutingSlip (336 | xlCommand)
#define xlcRouteDocument (338 | xlCommand)
#define xlcMailLogon (339 | xlCommand)
#define xlcInsertPicture (342 | xlCommand)
#define xlcEditTool (343 | xlCommand)
#define xlcGalleryDoughnut (344 | xlCommand)
#define xlcVbaObjectBrowser (345 | xlCommand)
#define xlcVbaDebugWindow (346 | xlCommand)
#define xlcVbaAddWatch (347 | xlCommand)
#define xlcVbaEditWatch (348 | xlCommand)
#define xlcVbaInstantWatch (349 | xlCommand)
#define xlcChartTrend (350 | xlCommand)
#define xlcPivotItemProperties (352 | xlCommand)
#define xlcWorkbookInsert (354 | xlCommand)
#define xlcOptionsTransition (355 | xlCommand)
#define xlcOptionsGeneral (356 | xlCommand)
#define xlcFilterAdvanced (370 | xlCommand)
#define xlcMailAddMailer (373 | xlCommand)
#define xlcMailDeleteMailer (374 | xlCommand)
#define xlcMailReply (375 | xlCommand)
#define xlcMailReplyAll (376 | xlCommand)
#define xlcMailForward (377 | xlCommand)
#define xlcMailNextLetter (378 | xlCommand)
#define xlcDataLabel (379 | xlCommand)
#define xlcInsertTitle (380 | xlCommand)
#define xlcFontProperties (381 | xlCommand)
#define xlcMacroOptions (382 | xlCommand)
#define xlcWorkbookHide (383 | xlCommand)
#define xlcWorkbookUnhide (384 | xlCommand)
#define xlcWorkbookDelete (385 | xlCommand)
#define xlcWorkbookName (386 | xlCommand)
#define xlcGalleryCustom (388 | xlCommand)
#define xlcAddChartAutoformat (390 | xlCommand)
#define xlcDeleteChartAutoformat (391 | xlCommand)
#define xlcChartAddData (392 | xlCommand)
#define xlcAutoOutline (393 | xlCommand)
#define xlcTabOrder (394 | xlCommand)
#define xlcShowDialog (395 | xlCommand)
#define xlcSelectAll (396 | xlCommand)
#define xlcUngroupSheets (397 | xlCommand)
#define xlcSubtotalCreate (398 | xlCommand)
#define xlcSubtotalRemove (399 | xlCommand)
#define xlcRenameObject (400 | xlCommand)
#define xlcWorkbookScroll (412 | xlCommand)
#define xlcWorkbookNext (413 | xlCommand)
#define xlcWorkbookPrev (414 | xlCommand)
#define xlcWorkbookTabSplit (415 | xlCommand)
#define xlcFullScreen (416 | xlCommand)
#define xlcWorkbookProtect (417 | xlCommand)
#define xlcScrollbarProperties (420 | xlCommand)
#define xlcPivotShowPages (421 | xlCommand)
#define xlcTextToColumns (422 | xlCommand)
#define xlcFormatCharttype (423 | xlCommand)
#define xlcLinkFormat (424 | xlCommand)
#define xlcTracerDisplay (425 | xlCommand)
#define xlcTracerNavigate (430 | xlCommand)
#define xlcTracerClear (431 | xlCommand)
#define xlcTracerError (432 | xlCommand)
#define xlcPivotFieldGroup (433 | xlCommand)
#define xlcPivotFieldUngroup (434 | xlCommand)
#define xlcCheckboxProperties (435 | xlCommand)
#define xlcLabelProperties (436 | xlCommand)
#define xlcListboxProperties (437 | xlCommand)
#define xlcEditboxProperties (438 | xlCommand)
#define xlcPivotRefresh (439 | xlCommand)
#define xlcLinkCombo (440 | xlCommand)
#define xlcOpenText (441 | xlCommand)
#define xlcHideDialog (442 | xlCommand)
#define xlcSetDialogFocus (443 | xlCommand)
#define xlcEnableObject (444 | xlCommand)
#define xlcPushbuttonProperties (445 | xlCommand)
#define xlcSetDialogDefault (446 | xlCommand)
#define xlcFilter (447 | xlCommand)
#define xlcFilterShowAll (448 | xlCommand)
#define xlcClearOutline (449 | xlCommand)
#define xlcFunctionWizard (450 | xlCommand)
#define xlcAddListItem (451 | xlCommand)
#define xlcSetListItem (452 | xlCommand)
#define xlcRemoveListItem (453 | xlCommand)
#define xlcSelectListItem (454 | xlCommand)
#define xlcSetControlValue (455 | xlCommand)
#define xlcSaveCopyAs (456 | xlCommand)
#define xlcOptionsListsAdd (458 | xlCommand)
#define xlcOptionsListsDelete (459 | xlCommand)
#define xlcSeriesAxes (460 | xlCommand)
#define xlcSeriesX (461 | xlCommand)
#define xlcSeriesY (462 | xlCommand)
#define xlcErrorbarX (463 | xlCommand)
#define xlcErrorbarY (464 | xlCommand)
#define xlcFormatChart (465 | xlCommand)
#define xlcSeriesOrder (466 | xlCommand)
#define xlcMailLogoff (467 | xlCommand)
#define xlcClearRoutingSlip (468 | xlCommand)
#define xlcAppActivateMicrosoft (469 | xlCommand)
#define xlcMailEditMailer (470 | xlCommand)
#define xlcOnSheet (471 | xlCommand)
#define xlcStandardWidth (472 | xlCommand)
#define xlcScenarioMerge (473 | xlCommand)
#define xlcSummaryInfo (474 | xlCommand)
#define xlcFindFile (475 | xlCommand)
#define xlcActiveCellFont (476 | xlCommand)
#define xlcEnableTipwizard (477 | xlCommand)
#define xlcVbaMakeAddin (478 | xlCommand)
#define xlcMailSendMailer (482 | xlCommand)

#ifdef __cplusplus
}   /* End of extern "C" { */
#endif /* __cplusplus */

Declare Function savitri Lib "c2vbtest.dll" (ByVal x As Double) As Double
Declare Function ganesh Lib "C:\wystup\c\MyProjects\c2vbtest\debug\c2vbtest.dll" _
        (ByVal x As Double) As Double
Declare Function shiva Lib "C:\wystup\c\MyProjects\c2vbtest\debug\c2vbtest.dll" _
        (ByRef x As Double) As Double
Declare Sub durga Lib "C:\wystup\c\MyProjects\c2vbtest\debug\c2vbtest.dll" ()
Declare Sub saraswati Lib "C:\wystup\c\MyProjects\c2vbtest\debug\c2vbtest.dll" _
        (ByVal x As Double, ByRef x_is_positive As Boolean)
 
 
 

Function vb_savitri(x As Double) As Double
    vb_savitri = savitri(x)
End Function

Function vb_shiva(x As Variant) As Double
    vb_shiva = x(1) * 2 + x(2) * 3
End Function
 

Function indicator(x As Double) As Double

Dim x_is_positive As Boolean

Call durga
Call saraswati(x, x_is_positive)
If x_is_positive Then
    indicator = 1
Else
    indicator = 0
End If

End Function