int count(mixed var[,int mode])

$a=array("a","b","c","d");
echo count($a);//输出个数4
$b=array("a"=>array(1,2,3),"b"=>array(4,5,6));
echo count($b,1);//输出 8
echo count($b);//输出 2

array array_count_values(array input)

$array=array(1,"a",1,"b","a");
$newarray=array_count_values($array);
print_r($newarray);//输出array([1]=>2 [a]=>2 [b]=>1)

array array_unique(array array)

$a=array("a"=>1,"b"=>2,"c"=>1);
print_r(array_unique($a));//输出 array([a]=>1 [b]=>2)

array array_filter(array input [,callback callback])

function myFun($var){
 if($var % 2==0){
 return true;
 }
}
$array= array("a"=>1,"b"=>2,"c"=>3,"d"=>4);
print_r($array,"myFun");//输出 array([b]=>2 [d]=>4)

bool array_walk( array &array,callback funcname [,mixed userdata])

function myFunc1($value,$key){
 echo "key=$key value=$value"
}
$a=array("a"=>"lin1","b"=>"lin2","c"=>"lin3");
array_walk($a,"myFunc1");
function myFunc2($value,$key,$str){
 echo "$key $p $value";
}
array_walk($a,"myFunc2");
function myFunc3($value,$key){
 $value="lin.su";
}
array_walk($a,"myFunc3");
print_r($a);//$a 是一个引用数组

array array_map(callback callback,array arr1[,arry ....]

function myFunc($v1,$v2){
 if($v1==$v2){
  return "same";
 }
 return "different";
}
$a=array(1,2,3);
$b=array(1,4,3);
print_r(array_map("myFunc",$a,$b));//输出 array([0]=>same [1]=>difference [2]=>same)
print_r(array_map(null,$a,$b));