Dynamic Memory Allocation

[kvarnerexpress 0]

I'm writing a didactic software that can store an undefined number of int in a dynamic list. I wrote a routine too that can delete an int and point the previous node to the next node after the one I've deleted.

But I've a problem: If I try to delete a number that isn't in the list, software crashes! Why? If the routine doesn't find the number it should simply do nothing

#include <stdio.h>#include <stdlib.h>void crealista();void visualizzalista();void eliminanumero();struct elenco {   int numero;   struct elenco *pun;   };int i,n;struct elenco *p,*paux, *paux2;main(){   char risp;	   crealista();   visualizzalista();}void crealista(){   printf("Quanti numeri vuoi inserire nella lista? ");   scanf("%i",&n);   if (n==0)      p = NULL;   else   {        p = (struct elenco *)malloc(sizeof(struct elenco));      printf("\nInserisci il valore: ");      scanf("%i",&p->numero);      paux = p;      for (i=1;i<=n-1;i++)      {         paux->pun = (struct elenco *)malloc(sizeof(struct elenco));         paux = paux->pun;         printf("\nInserisci il valore: ");              scanf("%i",&paux->numero);              if (i==n-1)                paux->pun = NULL;      }   }}void visualizzalista(){   char risp;	   system("cls");   paux = p;   while (paux != NULL)   {       printf("%i\n",paux->numero);      paux = paux->pun;   }   printf("\n\nVuoi eliminare un numero? (s/n): ");   scanf("%1s",&risp);   switch (risp) { 	case 's': eliminanumero();	break;	case 'n': exit(0);	break;	default:	printf("\n%i",risp);	printf("\n\nIl tasto scelto non permette azioni! Il programma viene terminato");	exit(0);}} void eliminanumero(){        int dato;        printf("Che numero vuoi eliminare? ");        scanf("%i",&dato);        paux = p;            while (paux != NULL)     {      if (paux == p && paux->numero == dato)      {       p = paux->pun;       free(paux);       break;      }      else if (paux->pun->numero == dato)      {       paux->pun = paux->pun->pun;       paux2 = paux->pun;       free(paux2);       break;      }      paux = paux->pun;     }visualizzalista();}

Mny thanks for the help

[mukund 0]

can u just post an english version of this program?I can then debug and give it to u

[switch 0]

I couldn't say what it is exactly, but I don't like the looks of the pointers (only because I find them confusing sometimes).

struct elenco *p,*paux, *paux2;

It just seems to me like you could do it without the pointers. I have found that alot of the time my unexplained crashes have something to do with memory management issues.

Generally, if I can't get one of my programs working, I try to do the same thing in a different way. That can often iron out bugs.

Also, you could try cleaning all the intermediate files (if you are using Visual C++) and then re-compiling. That's helped me before.

I can't really understand the Spanish (??) too well, but I think you may also find what's happening is that you have created an endless loop or something. This would normally make a program hang, rather than crash, but if every time the loop iterates new memory needs to be allocated or something, then the program would definately crash after a while.

Also, my best advice (although it sounds obvious) is to run the program in a Debug mode and step through line by line or set a lot of breakpoints. You get the idea.

Good luck mate, hope everything goes alright.

peace out!