I need to match a matrix to a space in another "Larger" matrix but trying the following code
int main ()
{
int Matriz [3][3],i,j;
int SubMatriz [3][3],a,b;
Matriz [0][0] = SubMatriz;
}
I try to match the space 0,0 of the first matrix to the whole submatrix, that is to say that this space of 1x1 becomes a 3x3 matrix, What am I doing wrong? or if someone knows what the correct way to do these matches is
What you want is not as simple as you think. If you declare a matrix such that:
int matriz[3][3];
The compiler reserves 9 consecutive positions in the stack to store the 9 values of the matrix. So before the following code:
int matriz[3][3];
for( int i=0; i<3; i++ )
{
for( int j=0; j<3; j++ )
matriz[i][j] = 3*(i*3+j)
}
Generates the following sequence in memory:
OFFSET: 00 01 02 03 04 05 06 07 08
VALOR: 00 03 06 09 12 15 18 21 24
However, if we declare the matrix dynamically:
int** matriz = new int[3];
for( int i=0; i<3; i++ )
matriz[i] = new matriz[3];
The map of memory is different. Instead of occupying 9 consecutive positions in memory we now have a first level composed of three pointers and in each of these positions we have 3 values. That is, at the end we have the 9 values that we want to store and three tip pointers.
Why do I tell you this scroll?
Basically because the arrays or vectors declared in the stack are pointers with special characteristics:
In short, to get an element of Matriz to point to SubMatriz you need that Matriz is an array of pointers ... but you have already seen that the structure of a pointer is different from that of a matrix in the stack. How to do it then?
You can get to simulate the use but it's not too nice:
int SubMatriz[3][3];
int* Matriz[3][3][3];
for( int i=0;i<3;i++)
Matriz[0][0][i] = reinterpret_cast<int*>(&SubMatriz[i]);