Collision Detection

Well, Iv'e been trying to implement collision detection to a ball and a plane surface, supposely a rectangle.
Theres a lot of rectangles, I store them in a vector.
By far, i havent been impressed by the collision detection, Any help if im doing it wrong?


//This is how i store a vector of rectangles;
static std::vector<std::vector<Bricks> > Level(sizeof(map)/sizeof(*map), std::vector<Bricks>(sizeof(map)/sizeof(*map)));

//Collision detection
bool Brick::Collide( float x, float y, float r )
{
float X, Y;
for( size_t xSize = 0; xSize < Level.size(); xSize++ )
{
for( size_t ySize = 0; ySize < Level[xSize].size(); ySize++ )
{
if(Level[xSize][ySize].alive)
{
if( x < Level[xSize][ySize].x )
{
X = Level[xSize][ySize].x;
}
else if( x > Level[xSize][ySize].x + Level[xSize][ySize].w )
{
X = Level[xSize][ySize].x + Level[xSize][ySize].w;
}
else
{
X = x;
}
if( y < Level[xSize][ySize].y )
{
Y = Level[xSize][ySize].y;
}
else if( y > Level[xSize][ySize].y + Level[xSize][ySize].h )
{
Y = Level[xSize][ySize].y + Level[xSize][ySize].h;
}
else
{
Y = y;
}
if( sqrt( pow((long double)X-x, 2)+pow((long double)Y-y, 2)) < r )
{
return true;
}
}
}
}
return false;
}



Can anyone help me out, To do a almost-perfect collision detection.
Also, How do i implement collision for the sides of the rectangles, Since the ball is a moving object, when the ball hits the sides, It goes crazy, like zigzag or something.
Thanks.