Question

I’ve seen this code for finding a Minor of a matrix:

RegMatrix RegMatrix::Minor(const int row, const int col)const{
  //printf("minor(row=%i, col=%i), rows=%i, cols=%i\n", row, col, rows, cols);
 assert((row >= 0) && (row < numRow) && (col >= 0) && (col < numCol));

 RegMatrix result(numRow-1,numCol-1);

 // copy the content of the matrix to the minor, except the selected
    for (int r = 0; r < (numRow - (row >= numRow)); r++){
  for (int c = 0; c < (numCol - (col > numCol)); c++){
   //printf("r=%i, c=%i, value=%f, rr=%i, cc=%i \n", r, c, p[r-1][c-1], r - (r > row), c - (c > col));
   result.setElement(r - (r > row), c - (c > col),_matrix[r-1][c-1]);
  }
 }
     return result;
}

This is the first time I encounter a code line like this: r < (numRow – (row >= numRow)).

What does this mean?

Answer 1

(row >= numRow) is a boolean expression. If operator>= has not been overloaded, it should evaluate to true if row is greater or equal to numRow, and to false otherwise. When casting this boolean to an integer for subtraction, it will become 1 if true, 0 else.