Visual C++ :: How To Define A Hash Map
May 15, 2014I want a speed of O(1) in search, insertion and deletion.
is std::map<> the way to go?
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Visual C++ :: Hash Table - How To Setup Static Variable
Apr 22, 2014I am having trouble getting the cout statements that I commented out to work properly. And I can't figure out why the first movie in the movies.txt file displays at the end of the list in my output screen when it should only display once as the first item. I am also having trouble figuring out where and how to set up the static variable.
Purpose : This assignment requires that you to develop a program using the classes listed above. Specifically you will build a hash table containing movie data. The collision strategy will be to build linked lists as the array elements.
Program Specifications : Your program will read the data from the file named Movies.txt located in the StudentFiles1.zip file on the Connections Portal. Each record contains 2 fields separated by a space. They are:
FieldsData Type
Motion Picture Association Code (MPAC)Integer
Movie NameString
Your application program will read each record, create a Movie structure instance and place that structure instance into the hash table.
You will need to modify the appropriate code to provide for an audit trail of the hash table construction. To accomplish this, you will use cout statements in the above class member functions. You will need to modify them to include couts, but the modifications will be relatively small. If not, you are doing it wrong. The hashing algorithm to use is:
Index = int ( 0.618033 * MPAC) % size
Make the array size a constant and set it to 10.
Include a counter for the number of collisions that occurred in building the hash table. Including a static variable in the LinkedList or List class is the best method for doing that.
See the sample audit trail below for the first 5 records on Movies.txt and the size of the hash table set to 3. This is shown for illustration only. The full file will have different locations calculated.
1101-Casablanca is being added
The hashed location is 2
There was no collision loading 1101-Casablanca
------------------------------------------------
1200-Duck Soup is being added
The hashed location is 0
There was no collision loading 1200-Duck Soup
------------------------------------------------
[Code] ....
After the above is displayed, prompt the user to enter the MPAC of a movie to locate. Produce an audit trail when locating the requested movie as shown below: Make sure you list all movies that have collided at the hashed location. That may also cause you to modify one of the existing ADTs a little.
Will search for 6601
at the hashed location is 2
There was a collision here with 6601-Wizard of Oz
There was a collision here with 1101-Casablanca
retrieved from hash table: 6601-Wizard of Oz
[Code] ....
Visual C++ :: How To Define Name Range With Excel Automation
Mar 4, 2015Using Excel Automation in Visual Studio 2010 C++, how do I define a name? As a user of Excel, you can enter a name that then can be used in formulas to refer to a range of cells. The range changes as the user inserts columns or rows. My program has worked with various versions of Excel dating back to the early 2000's.
I have a bunch of classes derived from COleDispatchDriver: CXLApplication, CXLRange, CXLWorkbook, CXLWorkbooks, and CXLWorksheet that have many functions, but I have no documentation... How to define a named range using functions of these classes (probably CXLRange)?
Visual C++ :: Define A Range Of Exit Codes In Application?
Feb 10, 2015I want to define a range of exit codes in my application. These codes will be used as a return value of ExitInstance function. I want to know the exit codes availables (values not used for example by windows to inform about an other error). When I force to crash my application, I get some different error codes: 8148, 10176.
What is the no available range exit codes?
Is this the ranges code unavailable?
[URL]
C :: How To Add New Value To Hash Table
Apr 18, 2013I have a problem with this function that adds a new value to the hash table or updates its data if the value already exists:
Code:
int tab_add(tab_disp *td, const object *value) the function should return:
TABDISP_OK if the value is correctly added, or TABDISP_ERROR if memory error, or TABDISP_INVALID if pointer td = NULL
The type of structure I am using is the following:
Code:
typedef struct {
char key[25];
char value[100];
} object;
[code]....
C :: How To Generate Hash Table
Jul 29, 2013Code: I have these two columns.
ID Group
0 2
1 2
2 3
3 4
4 4
5 4
6 4
7 4 Code: I want to store ID values on the bases of same Group, like we do in Hash table (key, value) .
Group ID
2 0,1
3 2
4 3,4,5,6,7
so when i said key 2 it will give me 0,1. how can i do it. As first i thought that i can use array of array but then how i can store the value of key. Now I am thinking of hash but i don't know how I will store and retrieve these values.
C++ :: Hash Tables And Queues
Jun 3, 2013For my homework I need to create a hash table with a size of 7. I also need to create a queue that holds 3 names maximum for each table position
View 1 Replies View RelatedC++ :: Duplicates In Hash Table
Feb 24, 2013I am having problems with this function:
bool HashTable::insert(char const * const key, const Player& aPlayer) {
//calculate the insertion position (the index of the array)
size_t index = calculateIndex(key);
for(int i=0; i < capacity; i++) {
[Code] ....
The inserting part works just fine, but the checking for duplicates where I compare the two values is crashing my program.
C++ :: Hash Function Implementation
Aug 26, 2013I was trying to implement a hash function in c++. This is just for learning purposes and not for a class project or assignment question. I had some questions before I started programming it:
1) Is it meaningful to have a hash function which maps string to string, string to int, int to int, float to int?
2) Can we have a template implementation which does element to element hashing?
I looked at several sources for a clear understanding of concepts and implementation technique but could not find a good source for reading about hashing.
C/C++ :: PJW Algorithm Of Hash Table
Jul 28, 2012I have a doubt in the PJW algorithm of the Hash Table.
What is the logic in shifting the bytes by this specified number as specified in the pjw algorithm.
C++ :: Get 15 Names And Then Hash Them - Segmentation Fault
May 3, 2013The 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.
Code:
//driver file
#include <iostream>
#include <vector>
#include <string>
using namespace std;
[Code] ....
C++ :: Construct Simple Hash Function?
Jun 3, 2013How to construct a simple hash function ? When the program executes, it will ask for your name. Type your name and it will print out a "hash code" (a number) from that name.
View 2 Replies View RelatedC++ :: Retrieve Object From Hash Table
Feb 25, 2013I'm trying to retrieve the Player object from my hash table so I can edit the content of that object. Here is what I have.
Player* HashTable::retrieve(char * key, Player& aPlayer) {
//calculate the retrieval position (the index of the array)
size_t index = calculateIndex(key);
//search for the data in the chain (linked list)
node * curr = table[index];
char id[100];
[Code] .....
Here I'm calling the retrieve and I need to return a pointer of that object.
Player* PlayerDB::FetchPlayer(char* name) {
Player* info = new Player();
out << "Fetching player " << """ << name << "" -- ";
if(h.retrieve(name, *info)) {
out << "Success!" << endl;
[Code] .....
And here is my call in main.
Player* outPlayer = NULL;
outPlayer = pdb.FetchPlayer("Sappho");
if (outPlayer != NULL) {
outPlayer->LevelUp();
}
I'm just trying to change the actual level of the player using the LevelUp function, but right now it is not making that change. I've been told I need to return a reference of the object in my retrieve function, but I thought that was what I was doing already.
C++ :: Runtime Error In Hash Table
Apr 25, 2013I am getting a strange runtime error when trying to run my hash table program. I have it separated in 3 separate files. I believe I have narrowed down where the error is occurring. It is either happening in insert(const &string s) or in the implementation of vector<list<string>> ht. I would appreciate some input. This is the implementation of insert():
void HTable::insert(const string &s) {
int h = hash(s);
cout<<h<<endl;
list<string> &tempList = ht[h];
[Code] .....
And it is giving me some sort of compilation error saying I cannot convert a type string to type list.
C++ :: Hash Table Remove Function
Apr 11, 2013I am working on creating a program using HashTables. This is for homework. This is the first time I am using and creating HashTables, so forgive me in advance as to I don't know entirely what I am doing. The main problem I am having right now is incorporating my remove() function. I can get the code to compile, but when I run test the program out, it crashes. The error that I am receiving is list iterator is not decrementable Here is my hashtable class as well as my remove() function. Also need to incorporate a print method.
class HTable
{
public:
HTable(int size);
[Code]....
C++ :: Separate Chaining Hash Table?
Nov 28, 2014my insert() function
template <class T>
class Node
{
public:
[Code]....
C++ :: Hash Table Of Function Pointers?
Dec 15, 2014Is it possible to create a hash table of function pointers so that functions can be referenced by their name (using a string?)
View 2 Replies View RelatedC++ :: Generate A Sha256 Hash With Std String?
May 22, 2013I am trying to generate a sha256 hash with std string, but i can't get this incomplete code puzzle to work [URL] .....
void main() {
string pbData1 = "HELLO";
BYTE* pbOutputBuffer;
CryptoPP::SHA256().CalculateDigest(pbOutputBuffer, (byte*)pbData1.c_str(), pbData1.size());
cout << pbOutputBuffer;
}
my problem is converting 'const char *' to 'const byte *' ..etc
C :: Setting Hash-table Entries To NULL?
Apr 21, 2013Here is my code so far:
Code:
//LINEAR CHAINING OR SEPERATE CHAINING...
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#define MAX_USERNAME_LEN 15
#define MAX_PASSWORD_LEN 20
[Code] ....
When I compile I get this error:
Code:
simpleauth.c: In function ‘initialize_table’:
simpleauth.c:179:30: error: incompatible types when assigning to type ‘DBEntry’ from type ‘void *’
I am sure its a simple error but I cannot seem to figure out how to set all the entries in the database to NULL. My plan is this:
1. Set all entries to NULL.
2. Check if entry is empty, if empty insert into hash-location, if not increment until empty...
Part 2 seems easy to me, but I cannot set them to empty....
C/C++ :: Hash Table - Interpreting Valgrind Output
Nov 22, 2014I have a large hash table, where each index has a container that has a doubly linked list. Things work up until releasing the memory. Each record is created with malloc, and each record->data is also created with malloc and the associated string is copied in using strcpy(). The table itself is released in another part of the program and doesn't produce and error.
/**
* valgrind --track-origins=yes
*/
==16898== Conditional jump or move depends on uninitialised value(s)
==16898== at 0x8049685: shFree (SpellHash.c:110)
==16898== by 0x8049352: unload (dictionary.c:115)
==16898== by 0x8048E64: main (speller.c:158)
==16898== Uninitialised value was created by a heap allocation
[Code] .....
How to interpret valgrind. Error resolved on a small problem. Now running into issues on large (>10000 words to check) problems. It appears the virtual machine just can't keep up for some reason. Running the code on my local computer produces no errors, memory usage is minuscule, and profile tools don't report any issues.
C++ :: Collision Free Hash On Unique Strings
Feb 28, 2013I have following method to calculate a 16bit hash on a per definition unique string:
uint16_t IReferenceHolder::getHash(const std::string &ref) {
return std::inner_product(ref.begin(), ref.end(), ref.begin(), (uint16_t)0) % 65437;
}
Actually it calculates an inner product on each character adding it to the last result (see [URL] .....).
65437 is the nearest prime to 2^16. In fact I never need the full range of 16 bit, therefore 65437 different hashes are enough.
Empirically it seems - on unique strings - to be collision free. The strings have an maximum size of 255.
C++ :: Ignoring Comment Line Beginning With Hash Sign
May 16, 2013My program had a requirement to ignore an input beginning with a # sign. The input is entered by user from keyboard. I wanted to know how to use cin.ignore to achieve this.
#include <iostream>
#include <algorithm>
#include <string>
#include <iomanip>
#include <limits>
#include <stdio.h>
using namespace std;
[Code] ....
The output:
Enter the string
# Comment
This is the # comment string.
Answer:
This is the string.
C++ :: Dynamically Allocating Hash Table Using Data From File
Nov 5, 2013I have an abstract based class and three derived classes. I also have a templated hash table class(using chaining as my collision resolution method, an array of stl lists), and a class to parse commands from a file, this also holds the instantiation of the hash table. My question is that since my command parsing class's constructor instantiates the hash table in the main driver(unable to modify) how can I make this dynamically allocated using data from the file?
template<class T>
class hashTable{
public:
hashTable(int size);
~hashTable();
[Code] .....
C++ :: Create A Map Based Hash Table For A Sparse Matrix?
Jul 24, 2014I have this assignment where I have to create a map based hash table for a sparse matrix. The professor has provided some code and I'm supposed to fill in parts of it to make it work.
He has given us a class sparseMatrix which we need to provide a hash function for. This hash function is to be defined in a Class TupleHash which is inside sparseMatrix. I think I got that part down. What is really confusing me is what he has done with some typedefs.
For one of them I had to declare an unorderd_map that maps a struct Tuple on to the class template argument Object. I did that like so:
typedef unordered_map<Object,Tuple,TupleHash> HashTable;
The next typedef was given to me like so:
typedef typename HashTable::value_type valueType;
This is giving me a world of unintelligible error messages. This is how it starts.
In instantiation of 'struct std::__detail::__is_noexcept_hash<int, sparseMatrix<int>::TupleHash>':|
recursively required from 'struct std::__and_<std::is_default_constructible<sparseMatrix<int>::TupleHash>, std::is_copy_assignable<sparseMatrix<int>::TupleHash>, std::__detail::__is_noexcept_hash<int, sparseMatrix<int>::TupleHash> >'|
C++ :: PolarSSL SHA512 Wrapper - Differing Hash Lengths
Apr 10, 2013I'm trying to write a little C++ wrapper around the PolarSLL SHA-512 / 384 implementation, the source code of which you can view here: [URL] .....
The problem I'm having is that the length of the digest is not always 64 bytes (for sha512) or 49 bytes (for sha384) as it's supposed to be, it often is, but not always.
I have pretty much used the code as it is on PolarSSL's website, except for wrapping it in an "impl" namespace. I also ran the self_tests, which all passed.
Here's the code I'm using to wrap the PolarSSL implementation:
namespace {
void sha4(const std::string& input, const sha_t& type, std::string& result) {
bool is_384 = (type == sha_t::SHA_384);
const unsigned char* in = reinterpret_cast<const unsigned char*>(input.c_str());
[Code] ....
When I do a strchr() for '' on the original (non-hex) values, the pointer position returned is the same as the checksums length, so I'm wondering if perhaps the sha4 implementation would shift bits around and one of them happens to become a '', null terminating the hash early?
C++ :: How To Program A Hash Map System Where Each Key Have Multiple Values Under Indexes
Nov 13, 2013How difficult would it be to program a hash-map system where each "key" can have multiple values under indexes?
For example: "Word" -> 45(index 0) , 67(index 1) , 12(index 2). What could I start with to program this or where could I find a pre-made system that does this?