Thread: Syntax question about c-mex s-functions

I'm creating a c-mex s-function that calls functions from an existing library. However, due to the way that the code is set up, I need to perform an extra step when calling these functions, by creating a pointer to each function. I have one function correctly set up -- the code compiles without problems, and the generated mex file can be successfully used. However, I'm trying to duplicate this working, template setup for several other functions, and am now getting a puzzling compile error. Details are below:

My correctly functioning code is:

Code:

typedef bool (*cwPointer)(int arg1, int arg2, char *fileName);
HINSTANCE dll; /* Pointer to the .dll */
cwPointer cw; /* Pointer to "cw" function within the .dll */ 
dll = LoadLibrary("AC.dll");
cw = (cwPointer)GetProcAddress(dll, "cw");
  
cw(1, 4, "SetupFile.txt");  /* call to the function */

And here is the 2nd function that I'm attempting to declare and use in the same way:

Code:

typedef int (*gawPointer)(double *arg1, double *arg2);
gawPointer gaw; /* Pointer to "gaw" function within the .dll */  
gaw = (gawPointer)GetProcAddress(dll, "gaw");
gaw(*state, *actionBuff);

Note that I excluded the "HINSTANCE dll" and "LoadLibrary" lines from the second set of code, since these only need to be included a total of once.

When this second set of code is included, I get compile failure, and the error messages include:

error C2143: syntax error : missing ';' before 'type'
--> this refers to the first line of the 2nd set of code; I notice that in the first set of code, within my code editor, "typedef" is in blue and "bool" is in black, indicating that only "typedef" is a reserved keyword. However, in the second set of code, both "typedef" *and* "int" are blue, indicating that, for some reason, the compiler is not interpreting these 2 similar "typedef" statements above equivalently.

Any suggestions about what I might need to do to resolve this error? Thanks in advance for your help!

> error C2143: syntax error : missing ';' before 'type'
Look for a missing ; a few lines earlier in the code.

If this line appears immediately after a #include, then look in the last included file for missing ;

Thanks for your suggestion, Tater. I did add your code, and I see that, apparently, my compiler *does* recognize the bool type. The compile error that I now receive is:

error C2371: 'bool' : redefinition; different basic types
cMEXsfcn.c(20) : see declaration of 'bool'

I'm not sure what the implication is. Is it possible that the issue of my editor not appearing to recognize 'bool' as a reserved type, may be a red herring? (Update: I see that anduril agrees, above.) Again, the first code example above (which contains the bool type) *does* compile and run without error, while it's the *second* set of code that fails. When I comment out the first section of code and only compile the second section (with the 2 deleted lines now restored), I still get a bunch of compile errors. When the first section is commented out, now the first line that is complained about is the function call on the last line of the 2nd code chunk. The error message concerns the argument type being used; maybe I will do some more investigating to ensure that all argument types & values are legit.

My specific error message is:
CMEXsfcn.c(312) : error C2440: 'function' : cannot convert from 'double' to 'double *'

The problematic function call is:

Code:

getActionWrapper(*temp830, *actionBuff, dt, includeNoise);

If I specify the first 2 arguments of the function call as "&argument", the new error message I get is:
CMEXsfcn.c(312) : warning C4047: 'function' : 'double *' differs in levels of indirection from 'double **'


The function specification line is:

Code:

 typedef int (*gawPointer)(double *state, double *actionBuff, double dt, bool includeNoise);

The declarations of the 4 arguments are (local variables within the same function):

double *actionBuff, *temp830, dt = 0.02;
bool includeNoise;

Ah... if I exclude any prefixes, and just specify the first 2 arguments as "arg1" and "arg2", the compiler errors above disappear. Keeping the rest of the post above, for reference purposes.

Thanks for your input, everyone. I need to keep in mind that a compiler error about one particular line (the 'missing semicolon' error I had been getting) might be caused by a completely unrelated problem in a different line of code...

> The 2 sections of code I posted above are in the same order in my actual code, i.e. the 2nd section immediately
> follows the first, and I don't see any missing semicolon in the first section...
In which case, the other C99 feature you're missing is the ability to mix declarations and statements.

Code:

typedef bool (*cwPointer)(int arg1, int arg2, char *fileName);
HINSTANCE dll; /* Pointer to the .dll */
cwPointer cw; /* Pointer to "cw" function within the .dll */ 
dll = LoadLibrary("AC.dll");
cw = (cwPointer)GetProcAddress(dll, "cw");
  
cw(1, 4, "SetupFile.txt");  /* call to the function */

typedef int (*gawPointer)(double *arg1, double *arg2);
gawPointer gaw; /* Pointer to "gaw" function within the .dll */  
gaw = (gawPointer)GetProcAddress(dll, "gaw");
gaw(*state, *actionBuff);

The red lines need moving up.