Ran into a logic issue with my hashing program that stores a state object. It's storing the object just fine now but I need to be able to search for it.
The user enters a state name and I'm supposed to be able to search for it. I am at a complete loss on how to handle hashing objects. Does anybody have a link with an example for me to look at?
here is the main
hashT class
StateData class
The user enters a state name and I'm supposed to be able to search for it. I am at a complete loss on how to handle hashing objects. Does anybody have a link with an example for me to look at?
here is the main
Code:
#include <iostream>
#include <fstream>
#include <string>
#include "hashT.h"
#include "stateData.h"
using namespace std;
int hashFunc(string name, int size);
int main()
{
hashT<StateData> HashTable(50);
int size = 15;
ifstream infile;
infile.open("states.txt");
if(!infile)
{
cout << "Error reading states file.\n";
exit(1);
}
char ch;
int year, order, key;
string state, capitol;
bool found;
getline(infile, state);
while(infile)
{
getline(infile, capitol);
infile >> year;
infile >> order;
StateData temp;
temp.setStateInfo(state, capitol, year, order);
infile.get(ch);
key = hashFunc(state, size);
HashTable.insert(key, temp);
getline(infile, state);
}
HashTable.print();
cout<<"Enter item to be deleted: ";
getline(cin, state);
cout<<endl;
key = hashFunc(state, size);
HashTable.remove(key, dtemp); //here is where I am lost. how do I get the StateData object dtemp? Do I need to completely
HashTable.print(); // replace my search function? It requires a StateData object.
infile.close();
system("pause");
return 0;
}
int hashFunc(string name, int size)
{
int i, sum, len;
i= 0;
sum = 0;
len = name.length();
for (int k=0; k < 15 - len; k++)
name = name + ' ';
for (int k = 0; k < 5; k++)
{
sum = sum + static_cast<int>(name[i]) * 128 * 128
+ static_cast<int>(name[i+1]) * 128
+ static_cast<int>(name[i+2]);
i = i+3;
}
return sum % size;
}Code:
private:
elemType *HTable; //pointer to the hash table
int *indexStatusList; //pointer to the array indicating
//the status of a position in the
//hash table
int length; //number of items in the hash table
int HTSize; //maximum size of the hash table
};
template <class elemType>
void hashT<elemType>::insert(int hashIndex, elemType& rec)
{
int pCount;
int inc;
pCount = 0;
inc = 1;
while(indexStatusList[hashIndex] == 1
&& HTable[hashIndex] != rec
&& pCount < HTSize / 2)
{
cout <<"inc = " << inc << endl;
pCount++;
hashIndex = (hashIndex + inc ) % HTSize;
// cout << "new hashIndex = " << hashIndex << endl;
inc = inc + 2;
}
if(indexStatusList[hashIndex] != 1)
{
HTable[hashIndex] = rec;
cout << "HTable["<< hashIndex <<"]" <<" = " << rec << endl;
indexStatusList[hashIndex] = 1;
length++;
}
else
if(HTable[hashIndex] == rec)
cerr<<"Error: No duplicates are allowed"<<endl;
else
cerr<<"Error: The table is full. "
<<"Unable to resolve the collision"<<endl;
}
template <class elemType>
void hashT<elemType>::search(int& hashIndex, const elemType& rec, bool& found)
{
int pCount;
int inc;
pCount = 0;
inc = 1;
while(indexStatusList[hashIndex] != 0
&& HTable[hashIndex] != rec
&& pCount < HTSize / 2)
{
pCount++;
hashIndex = (hashIndex + inc ) % HTSize;
inc = inc + 2;
}
if(indexStatusList[hashIndex] == 1 && HTable[hashIndex] == rec )
{
hashIndex = hashIndex;
found = true;
}
else
found = false;
}
template <class elemType>
bool hashT<elemType>::isItemAtEqual(int hashIndex, const elemType& rec)
{
return(HTable[hashIndex] == rec);
}
template <class elemType>
void hashT<elemType>::retrieve(int hashIndex, elemType& rec)
{
if(indexStatusList[hashIndex] == 1)
rec = HTable[hashIndex];
}
template <class elemType>
void hashT<elemType>::remove(int hashIndex, const elemType& rec)
{
bool found;
search(hashIndex,rec,found);
if(found)
{
indexStatusList[hashIndex] = -1;
length--;
}
else
cerr<<"The item to be deleted is not in the list."<<endl;
}Code:
private:
string name;
string capitol;
int yearAdmit;
int order;
};
#endif
StateData StateData::getStateData(string n) //once I've figured out the main, I think I can do this
{
if (name == n)
return this;
}
bool StateData::operator==(StateData &left)
{ return (this->name == left.name); }
bool StateData::operator!=(StateData &left)
{ return (this->name != left.name); }