linked linked insertion function - c

Question

Hello I am trying to create n number of lists. Each list is ordered linked list with a new instance. However, I also need a combined ordered linked list. Following is the code for the same. When it comes to each independent list I do not have any problems. However, when I am trying to insert every node into a globally declared linked list nodes, I am getting error(The input crashes with iteration of one node value.) Please have a look at the function and call highlighted to make things clear where I am exactly getting the error. Please make a note of global declarations. Thanks in advance.
#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>
struct node{
int number;
struct node*next;
};
typedef struct node NODE;
NODE*createlist(int),*rel_strt,*new_entry[100];
NODE *start1=NULL,*rear1,*m1,*temp11;
NODE *insert_in_end(NODE*node1);
int i,num,n2,j,v,u;
int main() {
v=0;u=0;
printf("\n Enter the number of lists:");
scanf("%d",&n2);
for(j=0;j<n2;j++) {
printf("\n\n Enter the number of inputs to the list %d: \n ",j+1);
scanf("%d",&num);
new_entry[v]=createlist(num);
display(new_entry[v]);
v++;
}
printf("\nThe final List is:");
display(start1);
return 0;
}
NODE*insert_in_end(NODE *node11) { //problem in this function
int inf1=node11->number;
if(start1==NULL) {
start1=rear1=node11;
} else {
m1=start1;
if(m1->number>inf1) {
node11->next=m1;
start1=node11;
} else {
while(m1->next) {
if(m1->next->number < inf1)
m1=m1->next;
else
break;
}
temp11=m1->next;
m1->next=node11;
node11->next=temp11;
}
}
return start1;
}
void display(NODE*nodex) {
while(nodex!=NULL) {
printf("%d ->",nodex->number);
nodex=nodex->next;
}
}
NODE *createlist(int n1) {
NODE *node1,*start,*rear,*m,*temp1;
start=NULL;
for(i=0;i<n1;i++) {
node1=(NODE*) malloc(sizeof(NODE));
int inf;
printf("Enter node value %d:",i+1);
scanf("%d",&inf);
node1->number=inf;
node1->next=NULL;
insert_in_end(node1); // error during second fuction call check function definition
if(start==NULL) {
start=rear=node1;
} else {
m=start;
if(m->number>inf) {
node1->next=m;
start=node1;
} else {
while(m->next) {
if(m->next->number < inf)
m=m->next;
else
break;
}
temp1=m->next;
m->next=node1;
node1->next=temp1;
}
}
}
return start;
}

Answer 1

I suggest you define a function insertValue that would make it much more convenient for you. It will also make your code much more readable.
The function is below and you should see that it is very close to what you have.
// Returns the new start of the list after inserting value in increasing order
Node* insertValue(Node * list, int value)
{
Node *newNode, *m;
newNode = malloc(sizeof(NODE));
newNode->number = value; // added this
newNode->next = NULL; // added this
if(list == NULL)
return newNode;
if(value < list->number)
{
newNode->next = list;
return newNode;
}
m = list;
while(m->next)
{
if(value < m->next->number)
break;
m = m->next;
}
newNode->next = m->next;
m->next = newNode;
return list;
}
Your main function should now iterate over reading the numbers for the different short lists as below. As you see, variable names are more explicit than yours. They are limited to the minimum and there are no global variables.
int main(int argc, char* argv[])
{
NODE *globalList = NULL, *lists[100];
int nbrOfLists, listNo, nbrOfVal, valNo, val;
printf("\n Enter the number of lists:");
scanf("%d", &nbrOfLists);
if(nbrOfLists < 0 || nbrOfLists > 100)
return -1;
for(listNo = 0; listNo < nbrOfLists; listNo++)
{
printf("\n\n Enter the number of inputs to the list %d: \n ",listNo+1);
scanf("%d", &nbrOfVal);
lists[listNo] = NULL;
for(valNo = 0; valNo < nbrOfVal; valNo++)
{
printf("Enter node value %d:", valNo+1);
scanf("%d", &val);
// Here we insert the value in both lists
lists[listNo] = insertValue(lists[listNo], val);
globalList = insertValue(globalList, val);
}
display(lists[listNo]);
}
display(globalList);
return 0;
}
Your display function is correct. I provide it below, but it's the same as yours. The problem you encountered was because I forgot to initialize the fields of the node after I malloc it.
void display(NODE * list)
{
while(list)
{
printf("%d ->", list->number);
list = list->next;
}
}