Passing strings as arguments to xll functions.

[JacksonRJones]

Yet another xll question. I'm trying to pass a filename as an argument to a
function defined in a c++ based xll file. The xll doesn't seem to be able to
handle this. I've tried coding a conversion from byte-counted strings to
null-terminated strings, but it didn't seem to help. If I run my conversion
and then write the new string, which should be a null-terminated c string, to
a file I get weird characters - like little rectangles. Anyways, I don't
quite know how to fix this. I've included my function table and the function
I'm trying to get to work. Any help is greatly appreciated.

static char gszFunctionTable[NUM_FUNCTIONS][NUM_REGISTER_ARGS][MAX_LENGTH] =
{
{" ReadInData", // procedure
" BJD", // type_text
" ReadInData", // function_text
" d1, filename", // argument_text
" 1", // macro_type
" Sample Add-In", // category
" ", // shortcut_text
" ", // help_topic
" Re", // function_help
" The first number to add.", // argument_help1
" The second number to add.", // argument_help2
},
{" GetNumberOfPoints",
" JJD",
" GetNumberOfPoints",
" d1,filename",
" 1",
" Sample Add-In",
" ",
" ",
" Gets number of points in data file",
" The index of the header to retrieve",
" ",

}

};

EXPORT int WINAPI GetNumberOfPoints(int d2,unsigned char* filename)
{

struct r32_data_header Old;
int nw3[3];

//
// load native format data file...should have .r32 suffix //
FILE *in;
int nw;
unsigned char* pos = filename;

int len = atoi( filename );

unsigned char* newstring = (unsigned char*)malloc( len * sizeof(char) + 1);
// later, free this
if( len > 0 )
{
while( isdigit( *pos ) ) // walk past the digits
{
pos++;
}
strcpy_s( newstring, pos, len ); // copy over the number of characters
specified
}
newstring[len] = '\0'; // add null-terminator



fopen_s(
&in,
"c:\\Jones\\excel stuff\\filetest.txt",
"w"
);

nw=fwrite(newstring,sizeof(filename),1,in);

// nw=fread((char *)&Old,sizeof(struct r32_data_header),1,in);

nw3[0] = Old.Nx;
nw3[1] = Old.Ny;
nw3[2] = Old.Nfreqs;

return 0;

fclose(in);

}