回显/打印特定元素

i tried this example on ajax here

and i wonder if i can echo/print a specific element of the array at the php side
let's say i just want to print the second element which is "lastName"
i tried echo $t2lpostData[1]
it gives me error
"Undefined offset: 1 in C:\wamp\www\thank-you.php on line 12"

help plz,,

echo $t2lpostData["lastName"]

You have to access it by name instead of index.