Setting struct value = segfault - c

Question

#include <stdio.h>
#include <stdlib.h>
#define true 1
struct hashRow {
char *key;
char *value;
};
struct hash_table {
int max;
int number_of_elements;
struct hashRow **elements;
};
int hashstring(const char *s)
{
int key = 0;
while (*s)
key = key * 37 + *s++;
return key;
}
int hash_fun(int key, int try, int max) {
return (key + try) % max;
}
struct hash_table *table;
int hash_insert(struct hashRow *data, struct hash_table *hash_table) {
int try, hash;
if(hash_table->number_of_elements < hash_table->max) {
return 0; // FULL
}
for(try = 0; true; try++) {
int hkey = hashstring(data->key);
hash = hash_fun(hkey, try, hash_table->max);
if(hash_table->elements[hash] == 0) { // empty cell
hash_table->elements[hash] = data;
hash_table->number_of_elements++;
return 1;
}
}
return 0;
}
struct hashRow *hash_retrieve(char *key, struct hash_table *hash_table) {
int try, hash;
for(try = 0; true; try++) {
int hkey = hashstring(key);
hash = hash_fun(hkey, try, hash_table->max);
if(hash_table->elements[hash] == 0) {
return 0; // Nothing found
}
if(hash_table->elements[hash]->key == key) {
return hash_table->elements[hash];
}
}
return 0;
}
int hash_delete(char *key, struct hash_table *hash_table) {
int try, hash;
for(try = 0; true; try++) {
int hkey = hashstring(key);
hash = hash_fun(hkey, try, hash_table->max);
if(hash_table->elements[hash] == 0) {
return 0; // Nothing found
}
if(hash_table->elements[hash]->key == key) {
hash_table->number_of_elements--;
hash_table->elements[hash] = 0;
return 1; // Success
}
}
return 0;
}
void insertsomething()
{
struct hashRow *toInsert;
toInsert = (struct hashRow *)malloc(sizeof(*toInsert));
printf("toInsert declared\n");
char *k = (char*)malloc(sizeof(char*));
char *v = (char*)malloc(sizeof(char*));
k = "sayhello";
v = "hello";
this is where I seem to be having the problem.
toInsert->key = k;
toInsert->value = v;
hash_insert(toInsert, table);
}
int main()
{
printf("calling insertsomething.\n");
insertsomething();
struct hashRow *gotten;
gotten = hash_retrieve("sayhello", table);
printf("test: %s\n", gotten->value);
}
I'm trying to create a hash table, but whenever I try to set a value in the toInsert struct pointer it segfaults. Can someone explain to me what I am doing wrong?

Answer 1

Try this:
void insertsomething()
{
struct hashRow *toInsert;
toInsert = (struct hashRow *)malloc(sizeof(*toInsert));
printf("toInsert declared\n");
/*
char *k = (char*)malloc(sizeof(char*)); // wrong size
char *v = (char*)malloc(sizeof(char*)); // wrong size
k = "sayhello"; // bad assignment
v = "hello"; // bad assignment
*/
toInsert->key = strdup("sayhello");
toInsert->value = strdup("hello");
hash_insert(toInsert, table);
}
Also, I can't spot where you reserve memory for your hash_table. Is it hidden somewhere else??