Is it possible to create a nested struct array? How?

Question

My goal with this piece of code is to create an array of 1000 positions, containing a struct which contains an int (to be used as a counter) and a nested struct initialized as an array of 100 positions. Am I designing this correctly?

As in, I'm trying to achieve a bidimensional table of 1000 columns by 100 rows, where these 100 rows each have the before mentioned int to be used as a counter/index variable, and each position in the 100 rows array to be comprised by the nested struct! This is what I got so far:

#define DATA_MAX 1000
#define MAX_CHAR_TIPO_MOV 60
#define MAX_CHAR_DESCRICAO 60
#define MAX_MOVIMENTOS 100
#define BUFFLEN 1024

char buffer[BUFFLEN];

typedef struct{
    int montante;
    int data;
    int periodicidade;
    char tipo[MAX_CHAR_TIPO_MOV];
    char descricao[MAX_CHAR_DESCRICAO];
}sistema;

typedef struct{
int indice;
struct sistema tabela[MAX_MOVIMENTOS]; /* Compiler gives me an error here: array type has incomplete element type */
}movimentos;

movimentos c[DATA_MAX];

/* Function to initialize arrays/structs in order to eliminate junk */


void inicializarfc(movimentos c[])
{
    int i, j;
//percorre o vector estrutura
for(i=0; i<DATA_MAX; i++)
    for(j=0; j<MAX_MOVIMENTOS; j++)
{
    c[i].[j].data = -1;
    c[i].[j].montante = -1;
    c[i].[j].periodicidade = -1;
    memset((c[i].[j].tipo), ' ', sizeof(c[i].[j].tipo));
    memset((c[i].[j].descricao), ' ', sizeof(c[i].[j].descricao));
   }
}

If indeed it is possible to create what I'm asking, how should I go about to access the structure members? Compiling in Codeblocks 10.05 in W7 using GCC.

Charles Salvia · Accepted Answer · 2012-03-30 18:34:37Z

1

You don't need to use the struct keyword in front of a typedef.

Just say:

sistema tabela[MAX_MOVIMENTOS];

To access members, just say:

movimentos m;
/* initialize data */
int x = m.tabela[0].montante; // accesses montante field of tabela[0]

answered Mar 30, 2012 at 18:34

Charles Salvia

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Comments

John Bode · Accepted Answer · 2012-03-30 19:04:06Z

Let's take a look at your declarations:

typedef struct{
   int montante;
   int data;
   int periodicidade;
   char tipo[MAX_CHAR_TIPO_MOV];
   char descricao[MAX_CHAR_DESCRICAO]; 
}sistema;  

typedef struct{ 
   int indice; 
   struct sistema tabela[MAX_MOVIMENTOS];
}movimentos;

The problem is that you're looking for a type named struct sistema, but you haven't declared a type like that; instead, you declared an anonymous struct type and created a typedef name sistema for it. To access a type named struct sistema, you would have to provide the struct tag in the definition:

struct sistema { ... };

The struct tag sistema and the typedef name sistema live in different namespaces; you could write

typedef struct sistema { ... } sistema;

and use both sistema and struct sistema interchangeably, although that would probably be confusing.

In this case, the simplest thing to do is to change

struct sistema tabela[MAX_MOVIMENTOS];

to

sistema tabela[MAX_MOVIMENTOS];

in the movimentos struct type.

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