CODEWITHSUNDEEP
cdata-structureslinked-list
chesslad
chesslad

Reputation: 171

Why am I counting one less in following code that counts number of elements in linked list

I am unable to figure out why am I counting 1 less in len() function defined below. len() function is supposed to count the number of elements in my linked list.

struct node {
    int data;
    struct node* link;
};

typedef struct node node;

node *root=NULL;

void append(void);
int len(void);

int main(void) {

    printf("\nCurrent length of list:\t%d\n",len());
    append();
    printf("\nCurrent length of list:\t%d\n",len());
    append();
    printf("\nCurrent length of list:\t%d\n",len());
    append();
    printf("\nCurrent length of list:\t%d\n",len());

    return 0;
}

void append(void) {

    node *tmp;

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

    printf("\nEnter data value\t\n");
    scanf("%d", &tmp->data);
    tmp->link=NULL;

    if(root==NULL){
        root=tmp;
    }
    else{
        node *ptr=root;

        while(ptr->link!=NULL){
            ptr=ptr->link;
        }
        ptr->link=tmp;
    }
}
int len(void) {
    int cnt=0;

    if(root==NULL)
        return 0;

    node *tmp=root;

    while(tmp->link!=NULL){
        ++cnt;
        tmp=tmp->link;
    }
    return cnt;
}

Current length of list: 0 // call to len(), Expected output : Correct

Enter data value 20 // call to append()

Current length of list: 0 // call to len(), Expected output : 1

Enter data value 191 // call to append()

Current length of list: 1 // call to len(), Expected output : 2

Enter data value 22 // call to append()

Current length of list: 2 // call to len(), Expected output : 3

Upvotes: 0

Views: 97

Answers (1)

Dennis
Dennis

Reputation: 514

You didn't count the last element. Try to trace your code.

If your linked list looks as the following

elem1 -> elem2 -> elem3 -> NULL

You count the elements 1 and 2 but not 3 because the link field of 3 is NULL.

Alter your code to the following and it will work

int len(void){
    int cnt=0;

    node *tmp=root;

    while(tmp!=NULL){
        ++cnt;
        tmp=tmp->link;
    }
    return cnt;
}

Upvotes: 1

Related Questions