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Reading and Writing Boost multi_array's to binary files

I am having problems writing a boost multi_array to a binary file and then reading it back.

I have a 3d multi_array which contains integers:

typedef boost::multi_array<int, 3> i3dArray;
typedef i3dArray::index iIndex;

Start Program
{
i3dArray contactMatrix(boost::extents[NOATOMS][NOATOMS][NO_DISTANCES_BINS]); // [167][167][150]

loop through files of atomic structures
{
count the number of atom types i see at different distances and increment the relevant array positions
i3dArray[i][j][k]++
}

// Verify values - this works (i.e. the i3dArray has correct values)
for(iIndex i = 0; i != 50; ++i)
for(iIndex j = 0; j != 50; ++j)
for(iIndex k = 0; k != 50; ++k)
cout << contact[i][j][k];

// Then i want to write this object to a binary file.
ofstream outfile( outname.c_str(), ios::out | ios::binary);
outfile.write( (char*)&contact, sizeof(contact) );
outfile.close();

// later i want to read in this object
ifstream Source(file, ios::in | ios::binary );
if (Source.fail())
exit(1);
Source.read( (char*)&contact, sizeof(contact) );
Source.close();

// Printing gives me a Segmentation Fault
for(iIndex i = 0; i != 50; ++i)
for(iIndex j = 0; j != 50; ++j)
for(iIndex k = 0; k != 50; ++k)
cout << contact[i][j][k];
}

I know this is a crude and incompetent method of writing an object but more correct ideas would be appreciated.

ASKER CERTIFIED SOLUTION

jkr

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keepthursdayspecial

ASKER

Oh, I see.

However, this doesn't write anything to the binary file.

keepthursdayspecial

ASKER

string outname = "out/pdb"+pdbfiles[t]+".ent.chem";
ofstream outfile( outname.c_str(), ios::out | ios::binary );
outfile.write( (char*)contactMat.data(), sizeof(int)*contactMat.size() );
outfile.close();

when i check the sizeof(int)*matrix i get 72 which is the same size as the output file.

cout << sizeof(int) << " " << sizeof(int) * contactMat.size() << " " << contactMat.size() << endl;

So 4 72 8.

The multi_array is [18] [18] [150] is this instance.

When I read the file back into a new multi_array of the same size i get an array of 0's.