Question

I can’t get the code below to compile (see errors). Advice on correction would be appreciated.

#include <stdio.h>

typedef struct {
  char    *fldName;
  unsigned fldLen;
} Field;

typedef struct {
  char    *fldPrompt;
  unsigned startRow;
  unsigned startCol;
} Prompt;

typedef struct {
  Field   *fields[];
  Prompt  *prompts[];
  unsigned numFlds;  <<< invalid field declaration after empty field 
} Form;                    <<< in '(incomplete) struct (no name)'.

Field  firstName = { "fName", 12 };
Field  surName   = { "sName", 25 };
Field  gender    = { "gder", 1 };

Prompt fn        = { "First Name : ", 4, 10 };
Prompt sn        = { "Surname    : ", 6, 10 };
Prompt gn        = { "Gender     : ", 8, 10 };

int main (void)
{
  Form aForm = { { &firstName, &surName, &gender },
                 { &fn, &sn, &gn}, 
                 3 };  <<<  Multiple initializers for the same element
  return 0;             <<<  Too many initializers
}

Answer 1

All your errors stem from the fact that you incorrectly declare arrays inside your struct. You have to specify the size of the array; you cannot just use empty brackets. I.e. this would work:

typedef struct {
    Field *fields[3];
    Prompt *prompts[3];
    unsigned numFlds;
} Form;

If you need to allow for varying number of elements, you’ll have to use something else. For example, you can have both fields be pointers:

Field **fields;
Prompt **prompts;

But then you’ll have to dynamically allocate and free memory for them, and you definitely won’t be able to use aggregate initializer to initialize the struct.