Well, I have some warnings that cause my program to crash, when I enter size 3.
Not all control paths return a value.
I am trying to solve N matrix, input, output and some operations. I store first column
_vec[0:size-1],last column _vec[size : (size*2)-1]
and diagonal
_vec[size*2 : size*3-2]
of matrix in 1-dimensional
array. The size of array is size of matrix * 3 -2
. The problem occurs when I overload () operators:
int _size = (_vec.size() +2) /3;
// when I switch from vector size to normal matrix size. f.e vector size: 7,
// my matrix size is 3.
int Matrix::operator()(int i, int j) const
{
int _size = (_vec.size() +2) /3;
if ((i >= _size || i < 0) || (j >= _size || j < 0)) throw OVERINDEXED;
if (i != j && j != 0 && j != _size - 1) return 0;
else {
if (j == 0)
{
return _vec[i];
}
else if (j == _size - 1)
{
return _vec[_size + i];
}
else if (i == j && j != 0 && j != _size - 1)
{
return _vec[(_size * 2) + i];
}
}
}
int& Matrix::operator()(int i, int j)
{
int _size = (_vec.size() +2) /3;
if ((i >= _size || i < 0) || (j >= _size || j < 0)) throw OVERINDEXED;
if (i != j && j != 0 && j != _size - 1) throw NULLPART;
else {
if (j == 0)
{
return _vec[i];
}
else if (j == _size - 1)
{
return _vec[_size + i];
}
else if (i == j && j != 0 && j != _size - 1)
{
return _vec[(_size * 2) + i];
}
}
}
Change the code like below for second function as well.
int Matrix::operator()(int i, int j) const
{
int _size = (_vec.size() + 2) / 3;
if ((i >= _size || i < 0) || (j >= _size || j < 0)) throw OVERINDEXED;
if (i != j && j != 0 && j != _size - 1) return 0;
else {
if (j == 0)
{
return _vec[i];
}
else if (j == _size - 1)
{
return _vec[_size + i];
}
else if (i == j && j != 0 && j != _size - 1)
{
return _vec[(_size * 2) + i];
}
}
return 0; // added this line
}
It requires some analysis to prove that all cases return.
And it seems your compiler doesn't do the full analysis
int Matrix::operator()(int i, int j) const
{
int _size = (_vec.size() + 2) /3;
if ((i >= _size || i < 0) || (j >= _size || j < 0)) throw OVERINDEXED;
if (i != j && j != 0 && j != _size - 1) return 0;
else {
if (j == 0)
{
return _vec[i];
}
else if (j == _size - 1)
{
return _vec[_size + i];
}
else if (i == j && j != 0 && j != _size - 1)
{
return _vec[(_size * 2) + i];
}
else
{
// No return here.
// But is this case reachable?
// yes, for (i, j) respecting:
// (0 <= i && i < _size) && (0 <= j && j < _size)
// && ((i == j) || (j == 0) || (j == _size - 1)) // #2
// && (j != 0) && (j != _size - 1) // #1
// && (i != j || j == 0 || j == _size - 1) // #3
// which after simplification results indeed in false.
// #1 simplifies #2 to (i == j) and #3 to (i != j)
}
}
}
On the other part, that means that you do useless "tests" that you can remove (and so please the compiler):
int Matrix::operator()(int i, int j) const
{
int _size = (_vec.size() + 2) /3;
if ((i >= _size || i < 0) || (j >= _size || j < 0)) throw OVERINDEXED;
if (i != j && j != 0 && j != _size - 1) return 0;
else {
if (j == 0)
{
return _vec[i];
}
else if (j == _size - 1)
{
return _vec[_size + i];
}
else // We have necessary (i == j && j != 0 && j != _size - 1)
{
return _vec[(_size * 2) + i];
}
}
}
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