resizing vectors

Howdy,

I have two ints:
int sizeX;
int sizeY;

I assign them values...
and then I want to make a multidimensional vector that size.

vector<vector<char > > maze;
so that maze will be sizeX*sizeY

Im having trouble looping through and doing push_back() when its multidimensional... please help.

Quote:

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Originally Posted by agilman

Im having trouble looping through and doing push_back() when its multidimensional... please help.

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Why don't you post that code? Certainly it's not the old 1 to N thing.

>Im having trouble looping through and doing push_back() when its multidimensional
Method 1 (using resize):

Code:

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  vector<vector<char > > maze;

  maze.resize(sizeX);

  for (int i=0; i<sizeX; i++)
  {
      for (int j=0; j<sizeY; j++)
      {
        maze[i].push_back(some_char);
      }
  }

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Method 2:

Code:

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  vector<vector<char > > maze(sizeX, vector<char>(sizeY));

  for (int i=0; i<sizeX; i++)
  {
      for (int j=0; j<sizeY; j++)
      {
        maze[i][j] = some_char;
      }
  }

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Thanks swoopy!
Thats exactly what I was looking for!

Quote:

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Im having trouble looping through and doing push_back() when its multidimensional.

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Code:

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int sizeX = 3;
int sizeY = 2;
vector<vector<int> > v;

vector<int> temp;
for(int i = 0; i<sizeX; i++)
{
        for(int j = 0; j<sizeY; j++)
        {
                temp.push_back(i*j);
        }

        v.push_back(temp);
        temp.clear();
}

for(vector<vector<int> >::iterator iter = v.begin(); iter != v.end(); ++iter)
{
        for(vector<int>::iterator jter = (*iter).begin(); jter != (*iter).end(); ++jter)
        {
                cout<<*jter<<" ";
        }
        cout<<endl;
}

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Of course, you shouldn't restrict yourself to using push_back():

Code:

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int sizeX = 4;
int sizeY = 3;
vector<vector<int> > v(sizeX, vector<int>(sizeY));

for(int i = 0; i<sizeX; i++)
{
        for(int j = 0; j<sizeY; j++)
        {
                v[i][j] = i*j;
        }
}

for(i = 0; i<sizeX; i++)
{
        for(int j = 0; j<sizeY; j++)
        {
                cout<<v[i][j]<<" ";
        }
        cout<<endl;
}

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