{"returnCode":"0","resultCode":"0","amount":1.00}
 $param= "{"returnCode":"0","resultCode":"0","amount":1.00}";
 $param=json_decode($param,true);

default amount is forcibly converted. Can you output it as is

Array
(
    [returnCode] => 0
    [resultCode] => 0
    [amount] => 1
)

wants

Array
(
    [returnCode] => 0
    [resultCode] => 0
    [amount] => 1.00
)

this effect meets the requirements
amount is automatically converted to number format 1? php bug?