多维数组告诉是否使用基于flag的值

Question

Array ( 
[0] => Array ( [address] => New York [address_flag] => 0 ) 
[1] => Array ( [address] => London [address_flag] => 1)

Lets say i have this array above, address 1 will always be there while address 2 can be null how can i get the value of address 2 if it is available;how can i tell that address 2 is null or not?

I am getting their value like this

foreach (address() as $value) {

echo $value['address']

}

UPDATE

I want to use the address with flag 0 only if address with flag 1 is not available..how do go about this?any idea is appreciated

Answer 1

<?php

function address(){

$a = array(array ( "address" => "New York", "address_flag" => 0 ), 
           array ( "address" => "London",   "address_flag" => 1 ),
           array ( "address" => "Amsterdam","address_flag" => 1),
           array ( "address" => null,       "address_flag" => null));

return $a;
}

$address = '';
$grouped_by_zero = array();
$grouped_by_one = array();
$array = address();

for ($i=0, $max = count($array); $i < $max; $i++ ){
    foreach($array[$i] as $key => $value) {
      if ($key == "address") {
         $address = $value;
      }     
      if ($key == "address_flag"){
          if ( $value === 0 ){
            array_push($grouped_by_zero,$address);
          } else if ($value === 1) {
              array_push($grouped_by_one,$address);
          }
      }// end outer if      
    }// end foreach
}// end for

foreach($grouped_by_zero as $item){
    echo $item . "
";
}
echo "
";
foreach($grouped_by_one as $item){
    echo $item . "
";
}
//output:

New York

London
Amsterdam

Live demo: http://3v4l.org/3utBH

By using the identity operator ===, a null value is excluded; only a value that is identical to a 0 or 1 is accepted.