Question

I’m writing a program for addding large numbers but without using BigInteger. I have a problem in long addition though.

int l = this.arr.length > arg.arr.length ? this.arr.length : arg.arr.length;        
byte[] result = new byte[l];    
byte carry = 0;

for(int i = 0; i < result.length; i++){
        byte sum;

        try{
            sum = (byte) (this.arr[i] + arg.arr[i] + carry);
        }
        catch(ArrayIndexOutOfBoundsException e){
            try{
                sum = (byte) (this.arr[i] + carry);
            }
            catch(ArrayIndexOutOfBoundsException ex){
                sum = (byte) (arg.arr[i] + carry);
            }
        }

        //carry
        if(sum > 9){
            result[i] = (byte) (sum % 10);
            carry = 1;
        }
        else{
            result[i] = sum;
            carry = 0;
        }
}

if(carry > 0){
        byte[] tmp = new byte[l+1];
        System.arraycopy(result, 0, tmp, 0, l);
        tmp[tmp.length - 1] = carry;
        result = tmp;
}

So to add two numbers I’m using try-catch twice to check whether there are any digits left in either of arrays. The method’s working fine but this try-catch thing doesn’t look so nice. Could I do this in any other way?

Answer 1

Use an if statement to check that i is < this.arr.length.