Segmentation Fault in Hashing problem need help

[billcozbee]

The point of this code is to get 15 names and then hash them. After one name is entered I get a segmentation Fault and the program crashes. any help would be appreciated.

//driver file
#include <iostream>
#include <vector>
#include <string>
using namespace std;


#include "hash.h"
#include "hash.cpp"


int main(void)
{
int a = 0;
hash x;
string name, word2;
cout << "Enter 15 names: " << endl;
while(a <= 14)
{
cin >> name;
x.insert(name);
a++;
}
x.display();
cout << "Enter a word to search for. Enter -999 to quit." << endl;
cin >> word2;
x.search(word2);
return 0;
}


//header file
#include <iostream>
using namespace std;




#ifndef HASH
#define HASH


typedef string hashelement;


class hash
{
public:


hash();
void insert(string word);
void display();
void search(hashelement & word);


private:


vector<hashelement> vec1;
int top;
string word;
};
#endif 

//implementation file

#include <iostream>
#include <vector>
#include <string>
#include <cassert>
using namespace std;


#include "hash.h"


hash::hash()
{
vector<hashelement> vec1;
vec1.assign(23, "?"); 
}


void hash::insert(string word)
{
int stop = 0;
int length = word.length()-1;
int loc = (word[0] + word[length]) % 23;
cout << vec1.size() << endl;
while (stop != 1)
{
if(vec1.at(loc) == "?")
{
vec1[loc] = word;
stop = 1;
}
else
loc++;
}
}


void hash::display()
{
for( int i = 0; i <= 22; i++)
cout << "Postition " << i << "= " << vec1[i] << endl;
}


void hash::search(hashelement & word)
{
int length = word.length()-1;
int loc = (word[0] + word[length]) % 23;
int found = 0;
while( found != 1)
{
if( vec1[loc] == word)
{
cout << word << " Word found at location: " << loc << endl;
found = 1;
}
else if(vec1[loc] == "?")
{
cout << word << " not found" << endl;
found = 1;
}
else
loc++;
}
}

[iMalc]

Why does your code have no indentation? That makes it difficult to read.
As it would be easier for me to ust move on to help someone who's code does have indentation, that is what I shall do for now.

[rcgldr]

What compiler / system are you running on? Do you not have access to a source level debugger? If you are running with windows, you can download and use microsoft visual c++ express for free, and it has a very good source level debugger.

[Salem]

Perhaps some warnings will illuminate....

$ g++ -Wall -Wextra -Wshadow foo.cpp
foo.cpp: In constructor `hash::hash()':
foo.cpp:47: warning: declaration of 'vec1' shadows a member of 'this'
foo.cpp: In member function `void hash::insert(std::string)':
foo.cpp:52: warning: declaration of 'word' shadows a member of 'this'
foo.cpp: In member function `void hash::search(hashelement&)':
foo.cpp:78: warning: declaration of 'word' shadows a member of 'this'


> #include "hash.cpp"
Add source files to the project, don't #include them.

This is what indented code should look like. I moved main to the end so it would compile without your complicated build step.

#include <iostream>
#include <vector>
#include <string>
#include <cassert>
using namespace std;

//driver file
#include <iostream>
#include <vector>
#include <string>
using namespace std;

//#include "hash.h"
//#include "hash.cpp"

//header file
#include <iostream>
using namespace std;

#ifndef HASH
#define HASH

typedef string hashelement;

class hash {
  public:
    hash();
    void insert(string word);
    void display();
    void search(hashelement & word);

  private:
    vector < hashelement > vec1;
    int top;
    string word;
};

#endif  

//implementation file

//#include "hash.h"


hash::hash()
{
    vector < hashelement > vec1;
    vec1.assign(23, "?");
}

void hash::insert(string word)
{
    int stop = 0;
    int length = word.length() - 1;
    int loc = (word[0] + word[length]) % 23;
    cout << vec1.size() << endl;

    while (stop != 1)
    {
        if (vec1.at(loc) == "?")
        {
            vec1[loc] = word;
            stop = 1;
        }
        else
            loc++;
    }
}

void hash::display()
{
    for (int i = 0; i <= 22; i++)
        cout << "Postition " << i << "= " << vec1[i] << endl;
}


void hash::search(hashelement & word)
{
    int length = word.length() - 1;
    int loc = (word[0] + word[length]) % 23;
    int found = 0;

    while (found != 1)
    {
        if (vec1[loc] == word)
        {
            cout << word << " Word found at location: " << loc << endl;
            found = 1;
        }
        else if (vec1[loc] == "?")
        {
            cout << word << " not found" << endl;
            found = 1;
        }
        else
            loc++;

    }
}

int main(void)
{
    int a = 0;
    hash x;

    string name, word2;
    cout << "Enter 15 names: " << endl;

    while (a <= 14)
    {
        cin >> name;
        x.insert(name);
        a++;
    }

    x.display();
    cout << "Enter a word to search for. Enter -999 to quit." << endl;
    cin >> word2;
    x.search(word2);

    return 0;
}

[billcozbee]

I put the tags in im not sure why there is no indentation

[billcozbee]

I was using dev c++ but I was not getting anything useful from the debugger

[Elysia]

Dev-C++ is not maintained anymore. I suggest you upgrade: SourceForge.net: IDE - cpwiki

[iMalc]

Fixing the things that Salem found when compiling this should resolve most of the problems.
Also, an insert or hash on an empty string could be problematic.

Why the awful hash? Any words which have the same first and last letters have an equal hash - that's very poor. Perhaps do a little research into what others have used for hashes.