what is wrong with my function?

I am using this function with my ADT Natural number in large precision
(My DT is

Code:

---

struct NatNo{ unsigned n; //number of digits
                      unsigned V[30];  // array of digits in order of introduction ( starting from 0)
                    }

---

)

Code:

---

void add(NatNo a, NatNo b, NatNo &sum)
{
        unsigned i;
       
        unsigned maxlength= a.n>b.n? a.n: b.n;
       
        init(sum, maxlenght); /* initializes sum with maxlength elements of 0 (s.n=maxlength and the array(s.V) with zero values ) */
       
        for(i=a.n;i<maxlength;i++)
                a.V[i]=0;
       
        for(i=b.n;i<maxlength;i++)
                b.V[i]=0;
               
            for(i=maxlength-1;i>=0;i--);
        {
              sum.V[i+1] += (a.V[i] + b.V[i]) % 10;  /* the sum will have an additional       
                                                                            digit(pozition 0) for overflow */
              sum.V[i] += (a.V[i] + b.V[i]) / 10;  // transportation
          }
             
    }

---

Seems that you want to add two numbers. But why are you resetting the operands a and b to zero before adding ?
Kurt

I am only adding zeroes in the number with less digits...

instead of init(sum,maxlenght) i use init(sum,maxlength+1) (as i said, the sum will have one digit more than the biggest number) but still does not solve the problem

Sorry, I overlooked that.
But

Code:

---

sum.V[i+1] += (a.V[i] + b.V[i]) % 10;
sum.V[i] += (a.V[i] + b.V[i]) / 10;

---

guess you have to do something like this

Code:

---

sum.V[i+1] = (sum.V[i+1] + a.V[i] + b.V[i]) % 10;
sum.V[i] = (sum.V[i] + a.V[i] + b.V[i]) / 10;

---

to correctly add transportation
Kurt

thanks, Kurt...
to make sure that addition works right, i introduced an auxilliary variable, which calculates the partial sums on every position(aux),and one for the transportation digit(t)

Code:

---

unsigned aux=0,t=0;
for(i =maxlength-1;i>=0;i--);
        {
            aux=t+a.V[i]+b.V[i];
            sum.V[i+1]= aux % 10;
            t=aux/10;
        }
sum.V[0]=t;

---

unfortunately, this STILL doesn't solve the problem...

Code:

---

for(i =maxlength-1;i>=0;i--);  // remove the semicolon

---

BTW I'm too lazy to create a compilable program from your code by myself.
You'd get much more help if you would create such a program. Also it's quite possible that the real error is somewhere else.
Kurt

the semicolon was embarrassing :D but the problem was indeed somewhere else...i eventually managed to solve it :)