[ Posted by Alfertson Cedano ] PHP tratamiento de nulos, vacíos, en blanco

fiddle_081491.php

<?php
$arrVacio=array();
$varDeclarada;
$arrValores=array(
    'vacio ("")'=>'', 
    'en blanco (" ")'=>' ', 
    'NULL'=>NULL, 
    'TRUE'=>TRUE,
    'FALSE'=>FALSE,
    '0 (como cadena)'=>'0',
    '0 (como entero)'=>0,
    '0.0 (como float)'=>0.0,
    'arr'=>$arrVacio,
    'Declarada pero sin valor'=>$varDeclarada,
    'No declarada'=>$strWhat,
    'byte null \0'=>'\ 0'
);
//$var="";
$strCSS="
<style>
table {
border-collapse: collapse;
}
td, th {
border: 1px solid #999;
padding: 0.5rem;
text-align: left;
}
</style>";
echo $strCSS;
//$strHTML=$strCSS;
$strHTML= "<table>";
$strHTML.="<thead>";
$strHTML.="<tr>";
$strHTML.= "<th>Valor</th><th>Tipo</th>
<th>isset(var)</th>
<th>empty(var)</th>
<th>is_null(var)</th>;
<th>if(var)</th>";


$strHTML.="</tr>";
$strHTML.="</thead>";
$strHTML.="<tbody>";
$str="";
//echo probarNulos($arrValores, $str);
$strDatos= probarNulos($arrValores,$str);
$strHTML.=$strDatos;
$strHTML.= "</tbody>";
$strHTML.= "</table>";
echo $strHTML;
function probarNulos($arrValores,$str){
    foreach ($arrValores as $k=>$v){
        $str.="<tr>";
        $str.="<td>";
        $str.=$k;  
        $str.="</td>";
        $str.="<td>";
        $str.=gettype($v);	
        $str.="</td>";
        $str.="<td>";
        $str.=var_export(isset($v),true);
        $str.="</td>";
        $str.="<td>";
        $str.=var_export(empty($v),true);
        $str.="</td>";
        $str.="<td>";
        $str.=var_export( is_null($v),true);
        $str.="</td>";
        $str.="<td>";
        $str.= $v ? 'true': 'false';
        $str.="</td>";


        $str.= "</tr>";
    }
    return $str;
}
?>