Good afternoon. I'm studying the hash table program from K&R. I understand name is the content I want to find. But I don't know what is the role of defn in this program.
Code:
#include <stdio.h>
#include <string.h>
struct nlist {
struct nlist *next; /* próxima entrada na cadeia */
char *name; /* nome definido */
char *text; /* texto substituído */
};
#define HASHSIZE 101
static struct nlist *hashtab[HASHSIZE];
/* hash: create hash value for string s */
unsigned hash(char *s)
{
unsigned hashval;
for(hashval = 0; *s != '\0'; s++)
hashval = *s + 31 * hashval;
return hashval % HASHSIZE;
}
/* lookup: look for s in hashtab */
struct nlist *lookup(char *s)
{
struct nlist *np;
for(np = hashtab[hash(s)]; np != NULL; np = np->next)
if(strcmp(s, np->name) == 0)
return np;
return NULL;
}
struct nlist *lookup(char *);
/* install: put(name, defn) in hashtab */
struct nlist *install(char *name, char *defn)
{
struct nlist *np;
unsigned hashval;
if( (np = lookup(name) ) == NULL) /* not found */
{
np = (struct nlist *) malloc(sizeof(*np));
if(np == NULL || (np->name = strdup(name)) == NULL)
return NULL;
hashval = hash(name);
np->next = hashtab[hashval];
hashtab[hashval] = np;
}
else
free((void *) np->defn);
if((np->defn = strdup(defn)) == NULL)
return NULL;
return np;
}
char *getword(char *w, int lim)
{
}
int main(void)
{
return 0;
}