#!F-adobe-helvetica-medium-r-normal--18*
#!N
#!CSeaGreen #!N
#!Run10 Examples #!N #!EC #!N #!N In the following examples, underscored
items are supplied by the user. #!N #!N #!F-adobe-times-bold-r-normal--18* (1) #!EF
No hash or compare function is provided at the time the
hash table is created. Stored elements are x, y, z points,
along with associated data values. #!N Note: Because no hash function
is provided, the pseudokey must be stored as the first long
integer word of the element. #!N #!CForestGreen #!N #!N #!F-adobe-courier-bold-r-normal--18* #!N
typedef struct #!N { #!N #!N long pseudokey; #!N #!N Point
pt; #!N float data; #!N } hashelement; #!EF #!N #!N #!EC
#!CForestGreen #!N #!N #!F-adobe-courier-bold-r-normal--18* #!N HashTable hashtable; #!N hashtable = DXCreateHash(sizeof(element),
NULL, NULL); #!EF #!N #!N #!EC #!CForestGreen #!N #!N #!F-adobe-courier-bold-r-normal--18* #!N
#!N for (i=0; i < #!F-adobe-times-medium-i-normal--18* number of points to insert
#!EF ; i++){ #!N element.pseudokey = GetKey(& #!F-adobe-times-medium-i-normal--18* current_point #!EF );
#!N element.pt = #!F-adobe-times-medium-i-normal--18* current_point #!EF ; #!N element.data = #!F-adobe-times-medium-i-normal--18*
current_data #!EF ; #!N #!N #!N DXInsertHashElement(hashtable, (Element)&element); #!N } #!EF
#!N #!N #!EC #!N #!N #!F-adobe-times-bold-r-normal--18* (2) #!EF If GetKey returns
the same pseudokey for two different points, the second will overwrite
the first because no compare function was provided to #!F-adobe-times-bold-r-normal--18* DXCreateHash()
#!EF . #!N #!N To extract elements from the hash table:
#!CForestGreen #!N #!N #!F-adobe-courier-bold-r-normal--18* #!N PseudoKey pkey; #!N hashelement *element_ptr; #!EF
#!N #!N #!EC #!CForestGreen #!N #!N #!F-adobe-courier-bold-r-normal--18* #!N #!N pkey =
GetKey(& #!F-adobe-times-medium-i-normal--18* point_to_search_for #!EF ); #!N #!N element_ptr = DXQueryHashElement(hashtable, (Key)&pkey);
#!EF #!N #!N #!EC #!N #!N GetKey that returns a pseudokey
given a point x, y, z: #!CForestGreen #!N #!N #!F-adobe-courier-bold-r-normal--18* #!N
PseudoKey GetKey(Key key) #!N { #!N Point *pt; #!N #!N pt
= (Point *)key; #!N return pt->x + 17*pt->y + 23*pt->z; #!N
} #!EF #!N #!N #!EC #!N #!N Alternatively, the hash function
GetKey can be provided at the time the hash table is
created. In that case the pseudokey does not need to be
part of the element. #!CForestGreen #!N #!N #!F-adobe-courier-bold-r-normal--18* #!N typedef struct
#!N { #!N Point pt; #!N float data; #!N } hashelement;
#!N #!N HashTable hashtable; #!N hashelement element; #!N #!N hashtable =
DXCreateHash(sizeof(element), GetKey, NULL); #!EF #!N #!N #!EC #!CForestGreen #!N #!N #!F-adobe-courier-bold-r-normal--18*
#!N #!N for (i=0; i < #!F-adobe-times-medium-i-normal--18* number_of_points_to_insert #!EF ; i++){
#!N element.pt = #!F-adobe-times-medium-i-normal--18* current_point #!EF ; #!N element.data = #!F-adobe-times-medium-i-normal--18*
current_data #!EF ; #!N #!N DXInsertHashElement(hashtable, (Element)&element); #!EF #!N #!N #!EC
#!N #!N where: #!CForestGreen #!N #!N #!F-adobe-courier-bold-r-normal--18* #!N PseudoKey GetKey(Key key)
#!N { #!N Point *pt; #!N #!N pt = (Point *)key;
#!N return pt->x + 17*pt->y + 23*pt->z; #!N } #!EF #!N
#!N #!EC #!N #!N To extract elements from the hash table:
#!CForestGreen #!N #!N #!F-adobe-courier-bold-r-normal--18* #!N hashelement *element_ptr; #!EF #!N #!N #!EC
#!CForestGreen #!N #!N #!F-adobe-courier-bold-r-normal--18* #!N element.pt = #!F-adobe-times-medium-i-normal--18* point_to_search_for #!EF ;
#!N element_ptr = DXQueryHashElement(hashtable, (Key)&element); #!EF #!N #!N #!EC #!N #!N
#!F-adobe-times-bold-r-normal--18* (3) #!EF This example uses a compare function. #!CForestGreen #!N
#!N #!F-adobe-courier-bold-r-normal--18* #!N typedef struct #!N { #!N Point pt; #!N
float data; #!N } hashelement; #!N #!N HashTable hashtable; #!N hashelement
element; #!N #!N hashtable = DXCreateHash(sizeof(element), GetKey, CompareFunc); #!EF #!N #!N
#!EC #!CForestGreen #!N #!N #!F-adobe-courier-bold-r-normal--18* #!N #!N for (i=0; i <
#!F-adobe-times-medium-i-normal--18* number of points to insert #!EF ; i++){ #!N element.pt
= #!F-adobe-times-medium-i-normal--18* current_point #!EF ; #!N element.data = #!F-adobe-times-medium-i-normal--18* current_data #!EF
; #!N #!N DXInsertHashElement(hashtable, (Element)&element); #!N } #!EF #!N #!N #!EC
#!N #!N where the compare function may be: #!CForestGreen #!N #!N
#!F-adobe-courier-bold-r-normal--18* #!N int CompareFunc(Key searchkey, Element element) #!N { #!N Point
*p, p1, p2; #!N hashelement *h; #!N #!N p = (Point
*)searchkey; #!N p1 = *p; #!N h = (hashelement *)element; #!N
p2 = h->pt; #!N if ((pl.x==p2.x)&&(p1.y==p2.y)&&(p1.z==p2.z)) #!N return 0; #!N else
#!N return 1; #!N } #!EF #!N #!N #!EC #!N #!N
#!N #!F-adobe-times-medium-i-normal--18* Next Topic #!EF #!N #!N #!Lpies,dxall1123 h Pick-Assistance Routines #!EL #!N #!F-adobe-times-medium-i-normal--18* #!N
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