Question

I am working on a program in C and using the SDCC compiler for a 8051 architecture device.
I am trying to write a function called GetName that will read 8 characters from Flash Memory and return the character array in some form. I know that it is not possible to return an array in C so I am trying to do it using a struct like this:

//********************FLASH.h file*******************************
MyStruct GetName(int i);  //Function prototype

#define NAME_SIZE  8

typedef struct
{
    char Name[NAME_SIZE];
} MyStruct;

extern MyStruct GetName(int i);


// *****************FLASH.c file***********************************
#include "FLASH.h"

MyStruct GetName( int i)
{
     MyStruct newNameStruct;

     //...
     // Fill the array by reading data from Flash 
     //...

     return newNameStruct;
}

I don’t have any references to this function yet but for some reason, I get a compiler error that says “Function cannot return aggregate.” Does this mean that my compiler does not support functions that return structs? Or am I just doing something wrong?

Answer 1

SDCC doesn’t support assignment and returning structs yet (if their Wiki is up-to-date):

Not yet implemented in sdcc:

• Data type double.
• Structures and unions can not be assigned, passed as function parameters or return values.
• register storage class specifier in function parameters.

Maybe you should make a

void GetName(MyStruct* ret_name, int i);

function instead.

---

That said, you should put the function prototype before the main and after the MyStruct. If there’s no prototypes a function will be assumed to return int.

MyStruct GetName(int i);
void main(void) { ...

(Also, the main function should be an int main(void) or int main(int argc, char** argv). It shouldn’t return void.)