$a = ';
Echo ' 1-----------'. ($a = = ")." <br> ';
Echo ' 2-----------'. ($a = = null). ' <br> ';
Echo ' 3-----------'. ($a = = false). ' <br> ';
Echo ' 4-----------'. ($a = = ' 0 '). ' <br> ';
Echo ' 5-----------'. ($a = = 0). ' <br> ';
$a = null;
Echo ' 6-----------'. ($a = = ")." <br> ';
Echo ' 7-----------'. ($a = = null). ' <br> ';
Echo ' 8-----------'. ($a = = false). ' <br> ';
Echo ' 9-----------'. ($a = = ' 0 '). ' <br> ';
Echo '-----------'. ($a = = 0). ' <br> ';
$a = ' 0 ';
Echo '-----------'. ($a = = ")." <br> ';
Echo '-----------'. ($a = = null). ' <br> ';
Echo '-----------'. ($a = = false). ' <br> ';
Echo '-----------'. ($a = = ' 0 '). ' <br> ';
Echo '-----------'. ($a = = 0). ' <br> ';
$a = 0;
Echo '-----------'. ($a = = ")." <br> ';
Echo '-----------'. ($a = = null). ' <br> ';
Echo '-----------'. ($a = = false). ' <br> ';
Echo '-----------'. ($a = = ' 0 '). ' <br> ';
Echo '-----------'. ($a = = 0). ' <br> ';
$a = false;
Echo '-----------'. ($a = = ")." <br> ';
Echo '-----------'. ($a = = null). ' <br> ';
Echo '-----------'. ($a = = false). ' <br> ';
Echo '-----------'. ($a = = ' 0 '). ' <br> ';
Echo '-----------'. ($a = = 0). ' <br> ';
Results of output
1.-----------1
2.-----------1
3.-----------1
4.-----------
5.-----------1
6.-----------1
7.-----------1
8.-----------1
9.-----------
1-----------
One-----------.
-----------
-----------1
-----------1
-----------1
-----------1
-----------1
-----------1
-----------1
-----------1
-----------1
-----------1
1-----------
-----------1
-----------1
$a = ';//0| ' 0 ' |false|null output is consistent
Echo ' 1-------'. (!empty ($a) = = "). ' <br> ';
Echo ' 2-------'. (!empty ($a) = = null). ' <br> ';
Echo ' 3-------'. (!empty ($a) = = false). ' <br> ';
Echo ' 4-------'. (!empty ($a) = = ' 0 '). ' <br> ';
Echo ' 5-------'. (!empty ($a) = = 0). ' <br> ';
Results of output:
1.-------1
2.-------1
3.-------1
4.-------1
5.-------1