void * problem for spreadsheet

[ramaadhitia]

Well hello everybody.i planned to develop simple spreadsheet for my homeworks,and then
i decided to use List instead of matrix to represent the spreadsheet cell.

well, code below is type declaration for my list in file matriks.h

/********** DEKLARASI matriks  **********/
/* File : matriks.h        */
/* deklarasi list untuk representasi sel pada matriks */
#ifndef matriks_H
#define matriks_H
#include "boolean.h"
#include <stdlib.h>

typedef struct
{
	void *value;
	int tipe;
}infotype;

typedef struct tElmtCell *address;

typedef struct tElmtCell 
{
	infotype *Info;
	int row;
	int column;
	address Next;
}ElmtCell;


typedef struct 
{
	address FirstCell;
}Matriks;

/*** Selector Notation***/

#define Nil       NULL
#define First(M)  (M).FirstCell
#define NextCell(C)  (C)->Next
#define Info(C)  (C)->Info->value
#define Tipe(C)  (C)->Info->tipe
#define Row(C) (C)->row
#define Column(C) (C)->column


/*** Prototype Primitif ***/

void CreateMatriks(Matriks *M);
boolean IsEmptyMatriks(Matriks M);
address Allocate(int tipe,void *value,int row,int column);

The list node contains structure named infotype which hold the value of cell and the Value type.1 for integer type,2 string for type,and 3 for storing formula.So i use void * in order to be able to store any kind of data type (integer,string,etc)

this is file matriks.c contains function body from matriks.h

void CreateMatriks(Matriks *M)
{
	First(*M) = Nil;
}

boolean IsEmptyMatriks(Matriks M)
{
	return (First(M) == Nil);
}


address Alllocate(int tipe,void *value,int row,int column)
{
	
	address P;
	printf("setelah alokasi \n");
	P=(address) malloc(sizeof(ElmtCell));
	printf("alokasi \n");
	if (P!=Nil)
	{
		Row(P) = rows;  
		Column(P) = column;
		Tipe(P)  = tipe;
		Info(P)  = isi;
		NextCell(P) = Nil;		
	}
	
	return (P);
}

well the problem is when i want to allocate some memory space for new list node,i use
Allocate function (umm, i made this function,you can see the function body in code above).The strange part is i can only use the Allocate function just once,you can try this code below to test the allocate function

#include "matriks.h"

int main (void)
{
	Matriks M1;
	CreateMatriks(&M1);
	address P = Allocate(1,(void *)1,1,1);
	address Q = Allocate(1,(void *)2,2,1);
	/*
	printf("it works \n");
	//InsertElement(&M1,1,1,1,1);
	printf("info cell is : %d \n",Info(First(M1)));
	//InsertElement(&M1,2,"rama adhitia",2,23);
	printf("hehe\n");*/
	scanf("%d");
	return 0;
}

So when i allocate address P the allocate function works nicely,but when i allocate address Q,it didnt work.I guess this problem occured because i use void * to store value in infotype structure.

Please help me guys!!

[Happy_Reaper]

How about not casting malloc, which you shouldn't be doing in the first place ?

If that doesn't work, what errors are you getting ?

[vart]

You are using

(C)->Info->value

while the Info pointer is dangling - it point nowhere... (actually it can point anywhere)
so when you write

Info(P) = isi;

your program should crash in most cases.
You should allocate memory for the Info struct also, before using it.

Or make it a struct member - not a pointer

[ramaadhitia]

hi,thank you for the solution vart,my code is working now