Thread: 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

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 but the problem was indeed somewhere else...i eventually managed to solve it