converting string into integer buffer

i am entering a number into a string and now i want to use each digit of that string for my application. I.e. somehow i want to convert that string into a buffer so that i can easily access each digit using syntax like a[0], a[1] etc.
Like i am entering 5 digit number into a string and then converting that string into integer using String.toInt() function. now how this integer value can be put on buffer. thanks.

First be clear whether you are using a String (uppercase S - a String object) or a string (lowercase s - an array of chars terminated with a zero)

If you use the latter then the digits will already be in an array.

Please post your code as it is now

Try this.
Doesn't anybody look things up for themselves anymore???