Modulo creating bad int for addresses in Hash Table? - c++

Question

HELP! I'm trying to create a hash table using Separate Chaining. For some unknown reason I cant seem to traverse and find all the original int I loaded. I suspect the modulo function is giving me bad addresses sometimes in both functions. First creating bad addresses on assorted int when creating the hash table and then sometimes searching the wrong addresses in the second function while attempting to traverse and confirm my list using modulo again. The hash table is populated by a basic random array of numbers and then I compare the created hash table with the original random array of int. Here is what I believe the culprit is causing all my troubles but I cant be 100% sure:
address = randARRAY[key] % MAX_KEYS;
And here is the function for creating the Hash Table using Separate Chaining. I generally have MAX_KEYS = 5000, tbSIZE = 8989, which is better than 75% Load factor somewhere around 55%:
void separateCHAINING(int *randARRAY,int tbSIZE,TABLE *head[]){
int key = 0,
address = 0,
collisions = 0,
newONE = 0;
randARRAY[MAX_KEYS + 1] = 0;
TABLE *newADDRESS[tbSIZE];
newADDRESS[tbSIZE] = new TABLE();
for(int a = 0; a < tbSIZE; a++){
newADDRESS[a] = NULL;
head[a] = NULL;
}
while(randARRAY[key] != 0){
address = randARRAY[key] % MAX_KEYS;
newADDRESS[address] = new TABLE;
newADDRESS[address]->key = randARRAY[key];
if(head[address] != 0){
newADDRESS[address]->next = head[address]->next;
head[address]->next = newADDRESS[address];
collisions++;
}
else{
newADDRESS[address]->next = head[address];
head[address] = newADDRESS[address];
newONE++;
}
key++;
}
cout << "total collisions: " << collisions << endl;
cout << "new: " << newONE << endl;
cout << "added: " << collisions + newONE << endl;
cout << "key: " << key << endl;
}
This created data appears to be passed without issue. I used gdb to create a ridiculously long list on one array index and it was all there in the second function without missing any nodes. This is why I think the addresses might be getting botched by modulo in both the function above and on this one below. This is apparently creating bogus addresses and then calling the wrong ones later. In the end Im never able to find all my int for the random array put in the Hash Table. Here is the function which uses modulo again and then tries to traverse and match the random array against the new hash table:
void tableTWO_MATCH(int *randARRAY,TABLE *HT_TWO[]){
int key = 0,
address = 0,
match = 0,
nomatch = 0;
randARRAY[MAX_KEYS + 1] = 0;
while(randARRAY[key] != 0){
address = randARRAY[key] % MAX_KEYS;
while(HT_TWO[address]->next != NULL && HT_TWO[address]->key != randARRAY[key]){
HT_TWO[address] = HT_TWO[address]->next;
}//end second while
if(HT_TWO[address]->key == randARRAY[key]){
match++;
}//end if
if(HT_TWO[address]->key != randARRAY[key]){
nomatch++;
}//end if
key = key + 1;
address = 0;
}//end outer while
cout << "match: " << match << endl;
cout << "not match: " << nomatch << endl;
cout << "key: " << key << endl;
}
As always thank you ahead of time for any assistance! I will be grateful if you can see where I'm messing up!

Answer 1

Well I guess I'm just a bone head! I used a boolean variable to check and see if a match was found at any point in time during traversal.
if(HT_TWO[address]->key == randARRAY[key]){
found = true;
}
I was trying to match nodes that had traversed past their match and getting poor results. Anyway This is how I changed my verification using boolen instead. Thanks for your help guys!
void tableTWO_MATCH(int *randARRAY,TABLE *HT_TWO[]){
int key = 0,
address = 0,
match = 0,
nomatch = 0;
bool found = false;
randARRAY[MAX_KEYS + 1] = 0;
while(randARRAY[key] != 0){
address = HASH(randARRAY[key],MAX_KEYS);
if(HT_TWO[address]->key == randARRAY[key]){
match++;
}
else{
while(HT_TWO[address]->next != NULL){
HT_TWO[address] = HT_TWO[address]->next;
if(HT_TWO[address]->key == randARRAY[key]){
found = true;
}
}//end second while
if(found == false){
nomatch++;
}
}
key = key + 2;
}//end outer while
cout << "not match: " << nomatch << endl;
cout << "key: " << key << endl;
}