Thread: Segmentation fault in linked list...doubt

Hi

I have seg fault in this code, any help will be apreciated.

Code:

#include <stdio.h>
#include <stdlib.h>


typedef struct churr{


    char mat[100];
    char pedido[100];
    float preco;
}INFO;


typedef struct elem{
    INFO nodo;
    struct elem *Seguinte;
    struct elem *Anterior;
}ELEM;


int recebeCliente(INFO info, ELEM **initlista, ELEM **fimlista)
{
    ELEM *novo;
    novo=(ELEM*)malloc(sizeof(ELEM));
    novo->nodo=info;
    novo->Seguinte=NULL;
    novo->Anterior=NULL;
    if(*initlista==NULL)
    {
        novo=*initlista;
        novo=*fimlista;
    }
    novo->Anterior=*fimlista;
    (*fimlista)->Seguinte=novo;
    *fimlista=novo;
return 0;
}
int main()
{
    ELEM *initlista=NULL, *fimlista=NULL;
    INFO info;
    printf("Matricula: \n");
    gets(info.mat);
    printf("Descricao: \n");
    gets(info.pedido);
    printf("Preco: \n");
    scanf("%f",&info.preco);
    getchar();
    recebeCliente(info,&initlista,&fimlista);
    return 0;
}

In this line
novo->Anterior=*fimlista;

If your code was in English it would be much more easier to help you.However you may say which is this language,so we can translate anything if necessary

The language is portuguese.
But most of the code is english, some words in Portuguese.
But if you have any doubt about any word just ask.

Many thanks

Code:

novo=*fimlista; /* Next you assigned an unknown value likely NULL again to novo */

Sure it is null.Check line 40 in the first post.So was that the problem Tim pointed out?

Could it be that novo is NULL. Possibly because of the following snippet:

Code:

    if(*initlista==NULL)
    {
        novo=*initlista;
        novo=*fimlista;
    }

When I ran this through my debugger it executed this if and at the end novo was NULL.

Jim

As i stated above novo is certaintly NULL,because at line 40 he declares *initlista and *fimlista and sets them at NULL.Then he does not do anything with them and at line 49 he calls a function,so both the pointers are set to NULL and so novo is NULL.

Yes,because it aux is NULL at line 52.

Code:

if(novo==NULL)
    {
        printf("Erro na lista...");
        return -1;
    }

This is at wrong point.You should write it after the if else structure you use in function recebeCliente

I have changed those lines after the if else structure and now i have

"Erro na lista", Error in list

So nothing is writed in that list, the strange is the pdf the teacher gave me has this...!!!

Teacher is a human,so he or she is able to makes mistakes.What do you want to do?Shall we try to correct it?

I want to insert clients into that list.

Check the example he gave us...

Code:

 
void insereIni(int num){
 
Lista* novo = (Lista*) malloc(sizeof(Lista)); 
novo->conteudo = num;  
novo->anterior= NULL;  
novo->proximo= NULL;  
if (lini==NULL) {    
lini=novo;
lfim=novo;
}
 else 
{
 
novo->proximo = lini;  
lini->anterior=novo;   
lini=novo;

What is Lista,lini,lfim?

Lista is list

lini is a variable to define initList, the other endList