Inserting and printing elements of a list in C

Question

So basically in the code below I am trying to create a list which contains some names and ages. I don't receive any errors or warnings but it doesn't print anything. What I am doing wrong?

#include <stdio.h>
#include <stdlib.h>
/* these arrays are just used to give the parameters to 'insert',
   to create the 'people' array 
*/

#define HOW_MANY 7
char *names[HOW_MANY]= {"Simon", "Suzie", "Alfred", "Chip", "John", "Tim",
              "Harriet"};
int ages[HOW_MANY]= {22, 24, 106, 6, 18, 32, 24};

typedef struct person
{
  char *name;
  int age;
  struct person *next;
}Person;


static void insert(Person *p, char *name, int age) 
{
  Person *headp = NULL;
  p = (Person*)malloc(sizeof(Person)); 
  if (p == NULL)
    abort();
  p->name = name;
  p->age = age;
  p->next = headp;
  headp = p;
}  

int main(int argc, char **argv) 
{

  Person *people=NULL;
  for (int i = 0; i < 7; i++) 
  {
    insert (people, names[i], ages[i]);
  }

  while (people != NULL)
  {
    printf ("name: %s, age: %i\n", people->name, people->age);
    people = people->next;
  }
  return 0;
}

Scott Hunter · Accepted Answer · 2016-11-11 18:42:42Z

1

Assigning to p inside the function does not change people from main, which is why you should find people to still be NULL when you go about printing.

You could return the new value for p from insert and assign that value to people.

answered Nov 11, 2016 at 18:42

Scott Hunter

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2 Comments

Raluca Damaris Lupeş Over a year ago

How exactly would I do that? What type should the function insert be?

Scott Hunter Over a year ago

If it is returning the value in p, it would be the same type as p.

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