implode() function can convert the array to string in PHP.
$array=array("array",,"is""string","now");
echo implode(" ",$array); // it print array is string now
implode("first argument is glue","second argument must be
array ")
so in above we glued the array value with one space and make a string in returns
join() function is can convert the array to string in PHP.
$a=array("a",,"b""c","d");
echo join(" ",$array);
join("first argument is glue","second argument must be array ")
so in above we glued the array value with one space and make a string in returns with join() function in PHP
join() function is alias of the implode() function in PHP
if you want to convert the array to JSON string.
json_encode() function will encode array to JSON, JSON is one type of string which formatted so it can convert JSON string to array again.
$response=array("stauts"=>"1");
echo json_encode($response);
The JSON format is used to information exchange between server to server or server to client
Server Ajax response will be sent back to the browser in the format of JSON