array_keys() 函数

　　函数返回包含数组中所有键名的一个新数组

$a=array("Volvo"=>"XC90","BMW"=>"X5","Toyota"=>"Highlander");
print_r(array_keys($a));
Array ( [0] => Volvo [1] => BMW [2] => Toyota )

$a=array("Volvo"=>"XC90","BMW"=>"X5","Toyota"=>"Highlander");
print_r(array_keys($a,"Highlander"));
Array ( [0] => Toyota )

$a=array(10,20,30,"10");
print_r(array_keys($a,"10",true));
Array ( [0] => 3 )

$a=array(10,20,30,"10");
print_r(array_keys($a,"10",false));
Array ( [0] => 0 [1] => 3 )

php常用函数

原文：http://www.cnblogs.com/jsonphp/p/7753338.html