TutHashCreateInt

Name

TutHashCreateInt — create a hash table with integer keys

Synopsis

T_HASH_TABLE TutHashCreateInt(init_size) 
T_INT4 init_size;

Arguments

init_size — the initial size of the hash table

Return Values

Returns a new hash table suitable for integer keys.

Diagnostics

None

Description

TutHashCreateInt creates a new hash table with integers for keys.

Caution

Providing an init_size that is too small causes the hash table to be resized often as new entries are inserted.

Examples

This example uses a hash table to look up string values from integer keys. Integer keys should be cast to (T_PTR) to avoid warnings from C compilers that understand function prototypes.

T_HASH_TABLE hash_table; 
 
hash_table = TutHashCreateInt(4); 
/* map integer directions to direction strings */ 
TutHashInsert(hash_table, (T_PTR)1, "NORTH"); 
TutHashInsert(hash_table, (T_PTR)2, "EAST"); 
TutHashInsert(hash_table, (T_PTR)3, "SOUTH"); 
TutHashInsert(hash_table, (T_PTR)4, "WEST"); 
 
TutOut("The value for 3 is %s.\n", 
        TutHashLookup(hash_table, (T_PTR)3));

This example is the hash function and test function used by TutHashCreateInt:

/* ============================================================= */ 
/*..utHashCalcInt -- hash function for ints */ 
static T_INT4 utHashCalcInt(key) 
T_PTR key; 
{ 
  return *(T_INT4 *)key; 
} /* utHashCalcInt */ 
/* ============================================================== */ 
/*..utHashTestInt -- test function for ints */ 
static T_BOOL utHashTestInt(key1, key2) 
T_PTR key1; /* really an int */ 
T_PTR key2; /* really an int */ 
{ 
  return *(T_INT4 *)key1 == *(T_INT4 *)key2; 
} /* utHashTestInt */

This example creates the hash table:

/* ============================================================== */ 
/*..TutHashCreateInt -- convenience func to create hash table with int keys */ 
T_HASH_TABLE TutHashCreateInt(init_size) 
T_INT4 init_size; /* initial size of hash table */ 
{ 
  return TutHashCreate(init_size, utHashCalcInt, utHashTestInt); 
} /* TutHashCreateInt */