Converting byte arrays to vectors

I have function - Stash::add - to recieve any kind of value,
and store that value as a byte array:

Code:

---

int Stash::add(const void* element) {
        ........
        ........
  // Copy element into storage,
  // starting at next empty space:
  int startBytes = next * size;  /* size - the size of the
                                  data type passed to add() */
  unsigned char* e = (unsigned char*)element; /* storage is a
                                              unsigned char array */
  for(int i = 0; i < size; i++)
    storage[startBytes + i] = e[i];
  next++;
  return(next - 1);
}

---

And - Stash::fetch - to get a value at a specific position in
that byte array:

Code:

---

void* Stash::fetch(int index) {
        ........
        ........
  // Produce pointer to desired element:
  return &(storage[index * size]);
}

---

Now, I have to change this codes' underlying data structure
to vector<char>.(This means to store each byte of 'element'
in subsequent positions of the vector,simulating a char array, right?)
So, I change it like this:

Code:

---

int Stash::add(const void* element) {
  unsigned char* e = (unsigned char*)element;
  for(int i = 0; i < size; i++)
    storage.push_back(e[i]); // now storage is changed to a vector
  next++;
  return(next - 1);
}

void* Stash::fetch(int index) {
  int ind = index;
  int trueInd = ind * size;
        ........
        ........
  unsigned char* intstore = new unsigned char[size];
  for(int x=0; x<=size; x++)
  intstore[x] = storage.at(trueInd+x);
  return &intstore;
}

---

In main(), the function calls are like this:

Code:

---

Stash intStash;
        ........
  for(int i = 0; i < 100; i++)
    intStash.add(&i);
  for(int j = 0; j < intStash.count(); j++)
    cout << *(int*)intStash.fetch(j) << endl;

---

Is the changes I have made are correct?
(If anybody wants the whole code to figure out what's actually happening,please be kind to give a little notification)

- Wish a beautiful march to all -

STL is a good solution. Check out various STL algorithms such as for_each(), etc.

Kuphryn

Thanks, gonna check STL algo soon.
But for now, please check whether the code is OK,
'cause it doesn't prints correct values.

Here's the whole thing:

Code:

---

// header.h
#include<vector>
using namespace std;

struct Stash {
  int size;      // Size of each space
  int quantity;  // Number of storage spaces
  int next;      // Next empty space
  // Dynamically allocated array of bytes:
  vector<char> storage;

  void initialize(int size);
  void cleanup();
  int add(const void* element);
  void* fetch(int index);
  int count();
  void inflate(int increase);
};

---

Code:

---

// Declare structure and functions:
#include "header.h"
#include <iostream>
#include <cassert>
using namespace std;
// Quantity of elements to add
// when increasing storage:
const int increment = 100;
 
void Stash::initialize(int sz) {
  size = sz;
  quantity = 0;
  //storage = 0;
  next = 0;
}
 
int Stash::add(const void* element) {
 // if(next >= quantity) // Enough space left?
  //  inflate(increment);
  // Copy element into storage,
  // starting at next empty space:-
  unsigned char* e = (unsigned char*)element;
  for(int i = 0; i < size; i++)
    storage.push_back(e[i]); // ***
  next++;
  return(next - 1);
}
 
void* Stash::fetch(int index) {
        int ind = index;
        int trueInd = ind * size;
  // Check index boundaries:
  assert(0 <= index);
  if(index >= next)
    return 0; // To indicate the end
  // Produce pointer to desired element:
  unsigned char* intstore = new unsigned char[4];
  for(int x=0; x<=size; x++)
  intstore[x] = storage.at(trueInd+x);
  //delete []intstore;
  return &intstore;
}

int Stash::count() {
  return storage.size(); // Number of elements in CStash
}
 
/*void Stash::cleanup() {
  if(storage != 0) {
    cout << "freeing storage" << endl;
//    delete []storage;
  }
} *

---

Code:

---

// main
#include "header.h"
//#include "../require.h"
#include <fstream>
#include <iostream>
#include <string>
using namespace std;
 
int main() {
  Stash intStash;
  intStash.initialize(sizeof(int));
  for(int i = 0; i < 100; i++)
    intStash.add(&i);
  for(int j = 0; j < intStash.count(); j++)
    cout << "intStash.fetch(" << j << ") = "
        << *(int*)intStash.fetch(j)
        << endl;
}

---

Some are commented out, 'cause not sure whether they are needed with vectors.

Since variables declared withing a function are local they are out of scope once the function exits when that happens they are destroyed and the memory the pointer points to is freed.

Code:

---

void* Stash::fetch(int index) {
  int ind = index;
  int trueInd = ind * size;
        ........
        ........
  unsigned char* intstore = new unsigned char[size];
  for(int x=0; x<=size; x++)
  intstore[x] = storage.at(trueInd+x);
  return &intstore; 
}

---