Question

Due to various restrictions, I have a method which only accepts an int argument. However, I want to pass this method a Struct.

So far, I have…

main(int argc, char* argv){
    Somestructure * name;
    //Name is malloced, things are put in it, etc.

    int address = (int) &name;
    method(address);
}

void method(int arg){
     Somestructure* thisStruct = (Somestructure*) arg;
     //Do stuff with thisStruct.
}

I thought this would assign thisStruct to point to the same struct as name in the main method, however when I attempt to use thisStruct in method, I get a Bus Error.
When I used this code…

    int structAddress = (int) &thisStruct;
    printf("[Method] Address : %d\n", structAddress);

It seems as though the addresses of name (inside main) and that of thisStruct (inside method) are different.

I’m a little new to C, but, does anyone have any idea what’s going on here?

This code will only run on a 32-bit system, so I need not worry about any 64-bit int/address problems.

Answer 1

Your problem is that you passed in &name, which is a pointer to a pointer to the struct. So, in the method, you are accessing the Somestructure ** as if it was a Somestructure *.

Just pass in (int)name.

(P.S. the usual way to define a “generic argument” is to use void *.)