C Linked Lists

• Linked lists are a way to store data with structures so that the programmer can automatically create a new place to store data whenever necessary.
• Specifically, the programmer writes a struct definition that contains variables holding information about something and that has a pointer to a struct of its same type.

Example 1
Creating a linked list. Function malloc is used to allocate memory space for the structure.

#include <stdio.h>
#include <stdlib.h>
struct node
{
        int item;
        struct node *next;
};
 
int main()
{
    struct node *root; /* This will be the unchanging first node */
 
    /* This will point to each node as it traverses the list */
    struct node *conductor;  
 
    //allocating space for the root   
    root = malloc(sizeof(struct node));
 
    root->next = 0;
    root->item = 777;
 
    conductor = root;
 
    int x;
 
    //create ten new nodes
 
    for(x = 1; x <=10; ++x)
    {
                /* Creates a node at the end of the list */
                conductor->next = malloc( sizeof(struct node) ); 
 
                /*checking that memory is allocated*/
                if ( conductor == 0 )
                {
                  printf( "Out of memory" );
                  return 0;
                } 
 
                conductor = conductor->next;
                conductor->item = x;
    }
 
    //marking the last as NULL
    conductor->next = 0;
 
    //conductor points to root again
    conductor = root;
 
    //print the list
    if ( conductor != 0 )  /* Makes sure there is a place to start */
    {
        while(conductor->next != 0)
        {
            printf(" [%d]-> ",conductor->item);
            conductor = conductor->next;
        }
    }
 
    getchar();
 
}