function saptamana() {
$cate_zile = date('d');
//$cate_zile = 28;
$calcul = substr($cate_zile / 7, 0, 4);
$exp = explode('.', $calcul);

if($calcul == 0) $saptamana = 1;
elseif($calcul == 1) $saptamana = 1;
elseif($calcul == 2) $saptamana = 2;
elseif($calcul == 3) $saptamana = 3;
elseif($calcul == 4) $saptamana = 4;

if($exp[0] == 0) $saptamana = 1;
elseif($exp[0] == 1 && $exp[1] > 0) $saptamana = 2;
elseif($exp[0] == 2 && $exp[1] > 0) $saptamana = 3;
elseif($exp[0] == 3 && $exp[1] > 0) $saptamana = 4;
elseif($exp[0] == 4 && $exp[1] > 0) $saptamana = 4;

return $saptamana;
}

echo 'Saptamana este: '.saptamana();