CODEWITHSUNDEEP
clinked-listsegmentation-faultdeclaration
user42037
user42037

Reputation: 39

Segmentation Fault C in use of linked list

I wrote a code that return the error of segmentation fault. The code is long but I wrote the essential part of that as follows. Note that All the variables of defined function inside the main functioned are defined and I tested the code ad it does not go inside the Function_1. That is whay I think the problem is about something like declaration 

    typedef struct node_type
{
    int data;
    struct node_type *next;
} node;

typedef node *list;

void Function_1(list R, int *Matrix, int Length, int A);
int main()
{
    int S = 5;
    int A = 1;
    int Mat1[5];
    //int *Mat = malloc(S*sizeof(int));
    int *Mat = &Mat1[0];
    printf("Enter the Matrix with length of 10:\n");
    for (int i = 0; i < S; i++)
    {
        scanf("%i", &(*(Mat+i)));
    }

    list head;
    head = (list)malloc(sizeof(node));
    head->next = NULL;
    for (int i = 0; i < S; i++)
        {
            printf("%d\t", *(Mat+i));
        }
    //printf("\nEnter the Array = \n");
    //scanf("\n%d", &A);
    printf("\nA = %i", A);
    Function_1(head, Mat, S, A);

    while (head != NULL)
    {
        printf("%d\t", head->data);
        head = head->next;
    }

        return 0;
    }


void Function_1(list R, int *Matrix, int Length, int A)
{
    printf("11111");
    list tail;
    tail = R;
    int Counter = 0;
    int i = 0;
    while (tail != NULL)
    {
        if (*(Matrix+i) == A)
        {
        Counter++;
        tail->next = (list)malloc(sizeof(node));
        tail->next->data = i;
        tail->next->next = NULL;
        tail = tail->next;
        }
    i++;
    }
R->data = Counter;
printf("%d", Counter);
}

Thanks

Upvotes: 0

Views: 58

Answers (1)

Utkan Gezer
Utkan Gezer

Reputation: 3069

With that code you've provided, I can say that the segmentation fault or access violation occurs due to the lack of <stdlib.h> or <malloc.h> inclusion, causing malloc to be assumed, and then head to get assigned with something else than what you'd expect.

I don't know, it might also be happening due to random dots in your code...

Edit:

As per your latest edit, within your loop inside your function Function_1, you are attempting to access the contents of the memory locations Matrix + i, with i having no bounds. It is fine to access there for i equals 0 to 4 but not after that, and there is nothing holding it from growing any larger.

Consider changing your while condition into i < 5 or something like that. I couldn't find out what your aim could be with while ( R != NULL ) but R never changes throughout the loop, so that condition won't become false after being true once, or the opposite.

Edit 2:

Similar when the while condition is rather tail != NULL which will evaluate to 0 only if malloc failed to allocate memory. i will most likely exceed 4 before you use up so much memory that malloc starts failing.

Upvotes: 1

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