code for subtracting 1 from a digit stored in an array using c

can any one help me with code开发者_如何转开发 that subtract 1 from a digit stored in an array using c++ (elementary mathematics) eg.. 100-1=99 and 98-1=97

If you have stored the digits in an array, you'll need to follow your elementary-school math on the array from right to left. "Borrow" from the next place to the left as needed.