_php tutorial on judging and elaborating based on empty function

$a = ";
Echo ' 1.-----------'. ($a = = "). '
';
Echo ' 2.-----------'. ($a = = null). '
';
Echo ' 3.-----------'. ($a = = false). '
';
Echo ' 4.-----------'. ($a = = ' 0 '). '
';
Echo ' 5.-----------'. ($a = = 0). '
';
$a = null;
Echo ' 6.-----------'. ($a = = "). '
';
Echo ' 7.-----------'. ($a = = null). '
';
Echo ' 8.-----------'. ($a = = false). '
';
Echo ' 9.-----------'. ($a = = ' 0 '). '
';
Echo '-----------'. ($a = = 0). '
';
$a = ' 0 ';
Echo ' one------------'. ($a = = "). '
';
Echo '-----------'. ($a = = null). '
';
Echo '-----------'. ($a = = false). '
';
Echo '-----------'. ($a = = ' 0 '). '
';
Echo '-----------'. ($a = = 0). '
';
$a = 0;
Echo '-----------'. ($a = = "). '
';
Echo '-----------'. ($a = = null). '
';
Echo '-----------'. ($a = = false). '
';
Echo '-----------'. ($a = = ' 0 '). '
';
Echo '-----------'. ($a = = 0). '
';
$a = false;
Echo '.-----------'. ($a = = "). '
';
Echo '-----------'. ($a = = null). '
';
Echo '-----------'. ($a = = false). '
';
Echo '-----------'. ($a = = ' 0 '). '
';
Echo '-----------'. ($a = = 0). '
';
results of the output
1.-----------1
2.-----------1
3.-----------1
4.-----------
5.-----------1
6.-----------1
7.-----------1
8.-----------1
9.-----------
Ten.-----------1
-----------.
-----------.
-----------1
-----------1
-----------1
-----------1
-----------1
-----------1
-----------1
-----------1
-----------1
-----------1
-----------1
-----------1
-----------1

$a = ';//0| ' The results of the 0 ' |false|null output are consistent
Echo ' 1.-------'. (!empty ($a) = = "). '
';
Echo ' 2.-------'. (!empty ($a) = = null). '
';
Echo ' 3.-------'. (!empty ($a) = = false). '
';
Echo ' 4.-------'. (!empty ($a) = = ' 0 '). '
';
Echo ' 5.-------'. (!empty ($a) = = 0). '
';

Results of the output:
1.-------1
2.-------1
3.-------1
4.-------1
5.-------1

http://www.bkjia.com/PHPjc/327672.html www.bkjia.com true http://www.bkjia.com/PHPjc/327672.html techarticle $a = '; Echo ' 1.-----------'. ($a = = "). ' BR '; Echo ' 2.-----------'. ($a = = null). ' BR '; Echo ' 3.-----------'. ($a = = false). ' BR '; Echo ' 4.-----------'. ($a = = ' 0 '). ' BR '; Echo ' 5.-----...

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