How i delete float 2D array in c++, with QT - c++

Question

Hi I'm using QT to my work and i can't delete a 2D float array from memory.
I'm working with images, so I need delete arrays for not consume much memory.
I tried this way but doesn't work:
int n = test.cols; // number of colums image.
int m = test.rows; // number of lines image
float soma[test.cols][test.rows]; // create a array 2D for operations...
for(int i = 0 ; i < n + 2 ; ++i)
{
for(int j = 0 ; j < m + 2 ; ++j) delete[] soma[i][j] ;
delete[] soma[i];
}
delete[] soma;

Answer 1

In this particular case the array is either on the STACK or in the DATA section of memory, not the HEAP. Only memory in the HEAP that is allocated with new[] can be deleted by the delete[] operator.
Not this example creates a series of discontinuous rows all over memory.
If you allocated the memory like this.
float ** soma = new float* [test.rows];
// WARNING UNITIALIZED CONTENT
for(int i = 0 ; i < test.rows; ++i) soma[i] = new float[test.cols];
You could then delete the memory like this
for(int i = 0 ; i < test.rows; ++i) delete [] soma[i];
delete [] soma;
However it is often better to allocate a single continuous image (if the dimensions are not too big). You then use a second array to record row offsets as pointers.
// WARNING UNITIALIZED CONTENT
float * buffer = new float [ test.rows * test.cols ]
float ** soma = new float* [ test.rows ];
for(int i = 0 ; i < m; ++i) soma[i] = soma + i * test.cols;
Then delete it like this
delete [] soma;
delete [] buffer;
Or just use std::vector.

Answer 2

Thx, i use std::vector, i'm working with images, static allocation is not a good way, so i use std::vector, for this work, Thank you for your attention, , follow my code now:
vector <float> lines(test.rows);
vector<vector<float> > colums(test.cols,lines);
for(int i=0;i<colums.size(); i++) {
for (int j=0;j<colums[i].size(); j++){
colums[i][j] = ((float)imagem.at<Vec3b>(j,i)[0]/(float)(imagem.at<Vec3b>(j,i)[0] + (float)imagem.at<Vec3b>(j,i) [1] + (float)imagem.at<Vec3b>(j,i) [2]))*255;
aux = (int) floor(colums[i][j] + 0.5);
colums[i][j] = aux;
test.at<Vec3b>(j, i)[0] = aux;
aux = 0;
colums[i][j] = ((float)imagem.at<Vec3b>(j,i)[1]/
(float)(imagem.at<Vec3b>(j,i)[0] +
(float)imagem.at<Vec3b>(j,i) [1] +
(float)imagem.at<Vec3b>(j,i) [2]))*255;
aux = (int) floor(colums[i][j] + 0.5);
colums[i][j] = aux;
test.at<Vec3b>(j, i)[1] = aux;
aux = 0;
colums[i][j] = ((float)imagem.at<Vec3b>(j,i)[2]/
(float)(imagem.at<Vec3b>(j,i)[0] +
(float)imagem.at<Vec3b>(j,i) [1] +
(float)imagem.at<Vec3b>(j,i) [2]))*255;
aux = (int) floor(colums[i][j] + 0.5);
colums[i][j] = aux;
test.at<Vec3b>(j, i)[2] = aux;
aux = 0;
}
}