Thread: linked list node removal using 'free'

I created a circular linked list in which I successfully manage to skip a specific node at a time(denoted 'candidate' in the code) , however I couldn't remove the requested node's allocated memory using 'free' procedure.Please see the below code(I also attached the C file for your convenience).
Your help is much appreciated!
Thanks!! Ron.

Code:

#include <stdio.h>
#include <stdlib.h>
typedef struct singleNode *nodePtr ;
struct singleNode
{
short int val ;
nodePtr next ; 
};
short int listLength(nodePtr);
void printCList(nodePtr); 
void main(){
 nodePtr member, Head, tmp=NULL, candidate=NULL;
 short int len=0,i,ind,j, LIST_SIZE=0,survivors;
    printf("Please define the list size,integer>=1\n");
 scanf("%d",&LIST_SIZE);
 for (i=1;i<=LIST_SIZE;i++){  // Building a regular linked list
  member = (nodePtr) malloc(sizeof(struct singleNode)) ;
  member->val = i ;                                           
  member->next = NULL ;
  if ( i == 1 ){ 
   tmp = member ;
   Head = member ;
  }
  else{ 
   tmp->next = member;
   tmp = tmp->next ;  
  }
 } 
 member->next = Head; // Turning the list into cirular one
 tmp = Head;
 printf("\n\nThe linked list: ");
 printCList(tmp);
 printf("Please enter the 'Every which location' and the number of survivors:m k\n");
 scanf("%d %d", &ind, &survivors);
 printf("(m=%d,k=%d)",ind, survivors);
 for (j=1;listLength(tmp)>=survivors;tmp=tmp->next,j++){  
  if (! (j%(ind-1)) ){
   candidate=tmp; 
   candidate->next=candidate->next->next; // skipping every m'th location
   //free(candidate); // ---> doesn't work 
  }
  if (listLength(tmp)==survivors){
    printf("\n\n The %3d survivors are located at places:\n", survivors);
    printCList(tmp);
    break;
  }
 }
}//main
void printCList(nodePtr temp){ // printing a circular linked list
    nodePtr head=temp;
 printf("%2d ",head->val);
    temp=temp->next;
 while(temp!=head){  
   printf("%2d ",temp->val);
   temp = temp->next;
 }
    printf("\n\n");
}
short int listLength(nodePtr pivot){
 short int k;
 nodePtr ptr;
 for (ptr=pivot,k=1;ptr->next!=pivot;ptr=ptr->next,++k); 
 return k;
}

It looks like your algorithm sets candidate to the node just before the one you want to remove. That's why you do candidate->next = candidate->next->next. You're basically making the list "skip over" whatever node candidate->next points to. You should fix the pointers using temp, and make candidate the node to delete:

Code:

        if (! (j%(ind-1)) ){
            candidate=tmp->next;  // candidate is the node to skip/delete
            tmp->next = tmp->next->next; // skipping every m'th location
            free(candidate); // now it should work
        }

Also, it's int main(void) and return an int when you're done, usually 0 for success. Read this link and this link.

It makes sense and works very well. Btw I do agree with anduril462 regarding the convention about using int main(void).
Thanks!!