hashtable.h File Reference

A simple, generic hash table implementation using a dynamic struct. More...

#include <stdbool.h>
#include <stddef.h>

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Classes
struct	hashtable
	The hash table structure. More...

Macros
#define	DELETED_NODE    ((void *)0xFFFFFFFFFFFFFFFUL)
	Special marker for deleted entries.

Typedefs
typedef const char *(*	get_key_func) (const void *)
	Function pointer type for extracting a string key from an object.

Functions
void	init_hash_table (hashtable *ht, get_key_func get_key, size_t size)
	Initializes the hash table with a given size.
void	free_hash_table (hashtable *ht)
	Frees the dynamically allocated table inside the hash table.
void	print_table (const hashtable *ht)
	Prints the current state of the hash table to the console.
bool	hash_table_insert (hashtable *ht, void *item)
	Inserts an object into the hash table using linear probing.
void *	hash_table_lookup (const hashtable *ht, const char *key)
	Looks up an object in the hash table by its string key.
void *	hash_table_delete (hashtable *ht, const char *key)
	Deletes an object from the hash table by its string key.

Detailed Description

A simple, generic hash table implementation using a dynamic struct.

Author

Alifoo

Date

2025-09-03

This file provides the public interface for a hash table that can store any kind of data. The table size is dynamic and allocated at runtime.

Typedef Documentation

get_key_func

typedef const char *(* get_key_func) (const void *)

Function pointer type for extracting a string key from an object.

The function takes a pointer to an object and returns a pointer to a string (the key) associated with that object.

Function Documentation

free_hash_table()

void free_hash_table

(

hashtable *

ht

)

Frees the dynamically allocated table inside the hash table.

Does not free the stored objects themselves; the user must do that separately.

Parameters

[in,out]

ht

A pointer to the hashtable instance.

hash_table_delete()

void * hash_table_delete	(	hashtable *	ht,
		const char *	key )

Deletes an object from the hash table by its string key.

This function marks the slot as deleted to preserve the probing chain.

Parameters

[in,out]	ht	A pointer to the hashtable instance.
[in]	key	The key string of the object to delete.

Returns

A pointer to the deleted object if found, otherwise NULL.

hash_table_insert()

bool hash_table_insert	(	hashtable *	ht,
		void *	item )

Inserts an object into the hash table using linear probing.

Parameters

[in,out]	ht	A pointer to the hashtable instance.
[in]	item	A pointer to the object to insert. The object is not copied.

Returns

true if the insertion was successful, false if the table is full.

hash_table_lookup()

void * hash_table_lookup	(	const hashtable *	ht,
		const char *	key )

Looks up an object in the hash table by its string key.

Parameters

[in]	ht	A pointer to the hashtable instance.
[in]	key	The key string to search for.

Returns

A pointer to the object if found, otherwise NULL.

init_hash_table()

void init_hash_table	(	hashtable *	ht,
		get_key_func	get_key,
		size_t	size )

Initializes the hash table with a given size.

Parameters

[in,out]	ht	A pointer to the hashtable instance.
[in]	get_key	A function that extracts a string key from stored objects.
[in]	size	Number of buckets to allocate for the table.

print_table()

void print_table

(

const hashtable *

ht

)

Prints the current state of the hash table to the console.

Useful for debugging and visualizing the table's contents.

Parameters

[in]

ht

A pointer to the hashtable instance.