要检查和显示的循环中的特定条目

A section of my code is as follows,

 foreach( $alpha as $key => $obj)
                        {
                         echo "<tr>"; 
                         echo "<td> ". $obj[$d] ."</td>";
                         echo "<td> ". $obj[$a] ."</td>";
                         echo "<td> ". $obj[$o] ."</td>";
                         echo "<td> ". $obj[$f] ."</td>";                           
                         echo "<td> ". $obj[$e] ."</td>";
                           echo "</tr>";  
                          }  

Here the array alpha is an associative array. The $d, $a, $o, $f, $e are the row values from an sql query. I want to check the value in the $obj[$f] and if a value exists then alert the user using javascripts' alert() command, that a value exists and if it doesnt then i want the looping to continue as usual.

try this

 foreach( $alpha as $key => $obj){
     if(!empty($obj[$f])){
          //has value, echo alert
          echo "<script>alert('object f contains value')</script>";
     } else {
          //no value there so echo rest of table
                     echo "<tr>"; 
                     echo "<td> ". $obj[$d] ."</td>";
                     echo "<td> ". $obj[$a] ."</td>";
                     echo "<td> ". $obj[$o] ."</td>";
                     echo "<td> ". $obj[$f] ."</td>";                           
                     echo "<td> ". $obj[$e] ."</td>";
                       echo "</tr>";
     }  
 }  

Can try this:

foreach( $alpha as $key => $obj)
{
 if(isset($obj[$f]) && !empty($obj[$f]))
 {
    echo "<script>alert('your comment')</script>";
    exit;
 }
 else
 {
    echo "<tr>"; 
    echo "<td> ". $obj[$d] ."</td>";
    echo "<td> ". $obj[$a] ."</td>";
    echo "<td> ". $obj[$o] ."</td>";
    echo "<td> ". $obj[$f] ."</td>";                           
    echo "<td> ". $obj[$e] ."</td>";
    echo "</tr>";
 }
}