php 在数组中查找某个值

<?php

$people = array("Peter", "Joe", "Glenn", "Cleveland");

if(in_array("Glenn",$people)){

  echo "Match found";

}else{

  echo "Match not found";

}

?>

<?php

$a=array("a"=>"Dog","b"=>"Cat");

if(array_key_exists("a",$a)){

    echo "Key exists!";

}else{

    echo "Key does not exist!";

}

?>

　　

<?php

$a=array("a"=>"Dog","b"=>"Cat","c"=>5,"d"=>"5");

echo array_search("Dog",$a);

echo array_search("5",$a);

?>