Simple question: find location of element in array [renamed]

please help me solve this simple question:

given an arrayA = [a, b, c] and
arrayB = [a1,a2,a3]

by using array[0].name, it will return “a”, is there any function that i can get the number “0” when i do something to “a” ?

I hope i make it clear here Xp

because i have 2 array here, i wanted to do something when the position of an element in an arrayA is same as the position of another element in arrayB.

for example
trace(array[0].name); -> output = A
trace(array[0].???); -> output = 0