multiplication of long integers

[susheela s]

Hi,

Im doing a multiplication of two large integers which are store in arrays(such as 2345 is in array as 2 in a[0], 3 in a[1] and so on)like this im storing integers in two arrays.The logic i have used is explained with code below,

class large{
    int no[SIZE];    //array is used to store the large number. Each digit of a the number is stored as an element..
                    // 123 is stored as no[3]={1,2,3}
public:
       large operator *(large& x){ // overload the * operator
/*
        34 x 46
        -------
          204            // these values are stored in the
         136            // two dimensional array mat[][];
        -------
         1564   // this the value stored in "large ret"
*/                                
        large ret;                
        int carry=0;
        int mat[2*SIZE+1][2*SIZE]={0};
        for(int i=SIZE-1;i>=0;i--){
            for(int j=SIZE-1;j>=0;j--){
                carry += no[i]*x.no[j];
                if(carry < 10){
                    mat[i][j-(SIZE-1-i)]=carry;
                    carry=0;
                }
                else{
                mat[i][j-(SIZE-1-i)]=carry%10;
                    carry=carry/10;
                }
            }
        }
        for( i=1;i<SIZE+1;i++){
            for(int j=SIZE-1;j>=0;j--){
                carry += mat[i][j]+mat[i-1][j];
                if(carry < 10){
                    mat[i][j]=carry;
                    carry=0;
                }
                else{
                    mat[i][j]=carry%10;
                    carry=carry/10;
                }
            }
        }
        for( i=0;i<SIZE;i++)
            ret.no[i]=mat[SIZE][i];
        return ret;
    }
 
    large (){
        for(int i=0;i<SIZE;i++)
            no[i]=0;
    }
 
    large (string _no){
        for(int i=0;i<SIZE;i++)
            no[i]=0;
        int index=SIZE-1;
        for( i=_no.length()-1;i>=0;i--,index--){
            no[index]=_no[i]-'0';
        }
    }
    void print(){        //print the large number
        int start=0;
        for(int i=0;i<SIZE;i++)
        if(no[i]!=0){
            start=i;
            break;        // find the first non zero digit. store the index in start.
        }
        for( i=start;i<SIZE;i++) // print the number starting from start till the end of array.
            cout<<no[i];
        cout<<endl;
        return;
    }
};
 

After multiplying the integers i store it in matrix form my problem is in storing in the matrix .If i do according to above program im unable to that..so plz anyone help me to sort out this problem.

thank u

[whodgson]

Why don`t you store the results in a vector and then work out how to read from that vector into the desired container form to present as a matrix?