Thread: Link List output

what's wrong with this code trying to rad from a file using link list ....

the output is something like this


787878789898988
6
6456
56
56
56
56
56


something that is not on the txt file.




void traverse (void);





/* Structure for printing the id.txt file */

struct id_card
{

int ID;
struct id_card *nextptr;
};




typedef struct id_card node;








void traverse (void)

{

FILE *fp;
node list1;
node *newptr, *currptr, *prevptr;


int NUM, i, ch ,j=0;
int NUM_2 = 6;


newptr= (node*)malloc(sizeof(node));

fp = fopen("id.txt","r");

if (fp == NULL)
{
printf("Unabale to open id.txt file \n");
exit(1);
}




currptr = newptr;
for ( i = 1; i<=8; i++)
{
NUM = getc(fp);
NUM = NUM-48;

newptr->ID = NUM;
printf ("%d",NUM);

newptr->nextptr=(node*)malloc(sizeof(node));
newptr=newptr->nextptr;
}

if(newptr !=NULL){
newptr->ID = NUM_2;
newptr->nextptr=currptr;
currptr=newptr;
}


else
{
printf("\n %d not inserted. No memory available.\n",NUM_2);
}


do{
j++;
printf("\n");
printf("%d", currptr->ID);
currptr=currptr->nextptr;
}
while(j<=8);


fclose(fp);

}




pls help !!!

Code:

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

void traverse(void);

/* Structure for printing the id.txt file */
struct id_card {
    int ID;
    struct id_card *nextptr;
};

typedef struct id_card node;

void traverse(void) {
    FILE *fp;
    node *newptr = NULL, *currptr = NULL;
    int NUM, i, j=0;
    int NUM_2 = 6;

    newptr= (node*)malloc( sizeof(node) );

    fp = fopen( "id.txt","r" );

    if(fp == NULL) {
        printf( "Unabale to open id.txt file \n" );
        exit( 1 );
    }

    currptr = newptr;
    for(i = 1; i<=8; i++) {
        NUM = getc( fp );
        NUM = NUM-48;

        /*!! this is the problem - newptr isn't pointing at a valid node */
        /*!! so trying to dereference it is a bad idea */
        /*!! you've got to malloc a node before trying to store data in it */
        newptr->ID = NUM;
        printf( "%d",NUM );

        newptr->nextptr=malloc( sizeof(node) );
        newptr=newptr->nextptr;
    }

    if(newptr != NULL) {
        newptr->ID = NUM_2;
        newptr->nextptr=currptr;
        currptr=newptr;
    } else {
        printf( "\n %d not inserted. No memory available.\n",NUM_2 );
    }

    do {
        j++;
        printf( "\n" );
        printf( "%d", currptr->ID );
        currptr=currptr->nextptr;
    }
    while(j<=8);

    fclose( fp );
}

Do you have any suggestion on how i can do that ?