CODEWITHSUNDEEP
c++arraysio
maruko
maruko

Reputation: 187

read and write array of float to file

I have an array of float in c++ and I would like to save it to a binary file (to save space) and to be able to read it again later. To do this, I wrote the following code to write the array:

float *zbuffer = new float[viewport[3]*viewport[2]*4];
//.....
//.. populate array
//.....
ofstream zOut(string(outFile).append("_geom.txt", ios::out | ios::binary));
zOut.write(reinterpret_cast<char*>(zBuffer), sizeof(float)*viewport[3] * viewport[2] * 4);
zOut.close();

And I re-open the file immediately afterwards to check that the data was saved correctly:

ifstream zIn(string(outFile).append("_geom.txt"), ios::in | ios::binary);
float *chBuffer = new float[viewport[3] * viewport[2] * 4];
zIn.read(reinterpret_cast<char*>(chBuffer), sizeof(float)*viewport[3] * viewport[2] * 4);
zIn.close();

However, when I check the two arrays for equality, I get wildly different values:

for (int i = 0; i < viewport[3]; i++)
{
    for (int j = 0; j < viewport[2]; j++)
    {
        int idx = 4 * (i*viewport[2] + j);
        if ((zBuffer[idx] != chBuffer[idx]) || (zBuffer[idx + 1] != chBuffer[idx + 1]) || (zBuffer[idx + 2] != chBuffer[idx + 2])) {
            cout << "1: " << zBuffer[idx] << " " << zBuffer[idx + 1] << " " << zBuffer[idx + 2] << endl;
            cout << "2: " << chBuffer[idx] << " " << chBuffer[idx + 1] << " " << chBuffer[idx + 2] << endl;
        } 
    }
}

Am I reading or writing the data wrongly? Are there any problems with the casting of the data I read?

Upvotes: 0

Views: 3437

Answers (1)

FJDU
FJDU

Reputation: 1473

Just look at these two lines:

ofstream zOut(string(outFile).append("_geom.txt", ios::out | ios::binary));
ifstream zIn(string(outFile).append("_geom.txt"), ios::in | ios::binary);

It seems to me that there is a typo in the first line. Maybe the intended is

ofstream zOut(string(outFile).append("_geom.txt"), ios::out | ios::binary);

Upvotes: 2

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