static void Main(string[] args)
{
BigNumber a = new BigNumber("12345");
BigNumber b = new BigNumber("6789");
Console.WriteLine(a + b);
Console.ReadKey();
}
public static BigNumber operator +(BigNumber arg1, BigNumber arg2)
{
int temp = 0;
BigNumber x = new BigNumber("0");
int len = arg1.size>arg2.size ? arg1.size : arg2.size;
for(int i=0; i<len; i++)
{
x.a[i] = arg1.a[i] + arg2.a[i] + temp;
x.a[i] %= 10;
temp = (arg1.a[i] + arg2.a[i]) / 10;
}
for(int j=len-1;j>0;j--)
{
Console.WriteLine(x.a[j]);
}
return x;
}