CODEWITHSUNDEEP
clinuxstructure
user3392539
user3392539

Reputation: 81

scanf taking value of a struct element giving seg fault in C linux

my scanf statement is giving seg fault. could you please tell me why?

typedef struct message1
{
    int call_id1;
    int lac;
    long int attribute;
    int conn_id;
    struct message1 *next1;
}M1;
M1 *last=NULL;
main()
{
    printf("\nEnter Call Id\t");
    scanf("%d",&last->call_id1);
}

Upvotes: 0

Views: 76

Answers (4)

Sunil Bojanapally
Sunil Bojanapally

Reputation: 12688

You haven't allocated memory for struct M1 and trying to access its memory contents which is the reason for segmentation fault,

Allocate memory dynamically as, M1 *last = malloc(sizeof(M1));

Upvotes: 1

Ferenc Deak
Ferenc Deak

Reputation: 35458

Obviously ... it is not initialized to a proper value:

M1 *last=NULL;

should be

M1 *last= (M1*)malloc(sizeof(M1));

Upvotes: 1

gangadhars
gangadhars

Reputation: 2728

Because you initialized your structure pointer with NULL.

M1 last;

is enough.

No need to give any pointer. If you wish to give it as pointer then use malloc

M1 *last;
last = malloc(sizeof(M1));

Upvotes: 2

KARTHIK BHAT
KARTHIK BHAT

Reputation: 1420

your trying to read into a struct which is not allocated memory

add

M1 *last = malloc(sizeof(struct message1)); // in global space

or

last =malloc(sizeof(struct message1)); // in main function

Upvotes: 2

Related Questions