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Based on feedback on an earlier question, I decided to implement the addition of two big ints by putting multiple digits in a node of a linked list. Can somebody take a look at my code and let me know if I am on the right track.

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
typedef struct node{
 int data;
 struct node* next;
} LList;
void printList(LList * list);
LList* pushToResult(LList* resultList,int entry){
 LList * temp = malloc(sizeof(LList));
 temp -> data = entry;
 temp -> next = resultList;
 resultList = temp;
 return resultList;
}
char* substr(char const* input,size_t start,size_t len){
 char *nstr = malloc(len+1);
 memcpy(nstr,input+start,len);
 nstr[len] = '0円';
 return nstr;
}
LList* convertToList(char* line){
 int i;
 int strSize = strlen(line);
 //Eight elements in every node
 int maxelem = 8;
 int currentPartition = 0;
 int currentIndex = 0;
 int totalPartitions = strSize/maxelem;
 LList* temp = NULL;
 
 for(i = 0;i < strSize - 1;i = i+maxelem){
 if(currentPartition >= totalPartitions){
 break;
 }
 char * currStr = substr(line,i,maxelem);
 int number = atoi(currStr);
 if(temp == NULL){
 temp = malloc(sizeof(LList));
 temp -> data = number;
 temp -> next = NULL;
 }else{
 LList * current = malloc(sizeof(LList));
 current -> data = number;
 current -> next = temp;
 temp = current;
 }
 currentIndex = i;
 currentPartition++;
 }
 currentIndex = currentIndex + maxelem;
 if((currentIndex > 0) && (currentIndex < (strSize - 1))){
 char * remainingStr = substr(line,currentIndex,strSize-1);
 int remainingNum = atoi(remainingStr);
 LList * current = malloc(sizeof(LList));
 current -> data = remainingNum;
 current -> next = temp;
 temp = current;
 }
 return temp;
}
void printList(LList * list){
 LList * counter = list;
 while( counter != NULL){
 printf(" %d ",counter -> data);
 counter = counter -> next;
 }
 printf("\n\n");
}
int main(){
 //Read number 1 from the input file into a linked list
 //The unit's place is the head and the most significant number is the tail
 //Read number 2 from the input file into a linked list
 //The unit's place is the head and the most significant number is the tail
 //Create temporary List where the elements will be added
 //Create the carry variable that will consist of the element's carry over after addition
 
 
 int counter = 0;
 ssize_t read;
 size_t len = 0;
 char * line = NULL;
 int carry = 0; 
 LList* num1 = NULL;
 LList* num2 = NULL;
 LList* result = NULL; 
 FILE * input = fopen("input.txt","r");
 if(input == NULL){
 exit(EXIT_FAILURE);
 }
 while((read = getline(&line,&len,input)) != -1){
 printf("Read the line %s",line);
 //If it's the first line
 if(counter == 0){
 num1 = convertToList(line);
 printf("Printing the list containing the num1(it will be in reversed order)\n");
 printList(num1);
 }else{
 num2 = convertToList(line);
 printf("Printing the list containing the num2(it will be in reversed order)\n");
 printList(num2);
 }
 counter++;
 }
 fclose(input); 
 while((num1 != NULL) || (num2 != NULL)){
 if(num1 != NULL){
 carry = carry + (num1->data);
 num1 = num1 -> next;
 }
 if(num2 != NULL){
 carry = carry + (num2 -> data);
 num2 = num2 -> next;
 }
 //Get the carry and the left over
 int carryOver = carry / 100000000;
 int leftOver = carry % 100000000;
 //put the left over in the result linked list
 //printf("Pushing the result into the result list");
 result = pushToResult(result,leftOver);
 carry = carryOver;
 
 }
 //Done with traversing the linked lists,if the carry is zero no need to push the value to the result
 //else push the value to the result
 if(carry != 0){
 result = pushToResult(result,carry);
 }
 //Print the result here
 printf("Printing out the result of the addition\n");
 printList(result);
}