大数相加

void Add(char fx[],int y)
{
    char fy[100];
    itoa(y,fy,10);
    int xlen = strlen(fx);
    int ylen = strlen(fy);
    int i,j,up=0,h=0,k;
    if(xlen>=ylen)
    {
        for(i=ylen-1,j=xlen-1;j>=0;i--,j--)
        {
            if(i>=0)
            {
                k = (fx[j] - ‘0‘) + (fy[i] - ‘0‘) + up;
                if(k>=10)
                {
                    k = k - 10;
                    s[h] = k+‘0‘;
                    h++;
                    up = 1;
                }
                else
                {
                    s[h] = k + ‘0‘;
                    h++;
                    up = 0;
                }
            }
            else
            {
                k = (fx[j] - ‘0‘) + up;
                if(k>=10)
                {
                    k = k -10;
                    s[h] = k+‘0‘;
                    h++;
                    up = 1;
                }
                else
                {
                    s[h] = k + ‘0‘;
                    h++;
                    up = 0;
                }
            }
        }
        if(up==1)
        {
            s[h] = ‘1‘;
            h++;
        }
    }
    else
    {
        for(i=xlen-1,j=ylen-1;j>=0;i--,j--)
        {
            if(i>=0)
            {
                k = (fx[i] - ‘0‘) + (fy[j] - ‘0‘) + up;
                if(k>=10)
                {
                    k = k - 10;
                    s[h] = k+‘0‘;
                    h++;
                    up = 1;
                }
                else
                {
                    s[h] = k + ‘0‘;
                    h++;
                    up = 0;
                }
            }
            else
            {
                k = (fy[j] - ‘0‘) + up;
                if(k>=10)
                {
                    k = k - 10;
                    s[h] = k+‘0‘;
                    h++;
                    up = 1;
                }
                else
                {
                    s[h] = k + ‘0‘;
                    h++;
                    up = 0;
                }
            }
        }
        if(up==1)
        {
            s[h] = ‘1‘;
            h++;
        }
    }
    for(i=h-1,j=0;i>=0;i--,j++)
    {
        S[j] = s[i];
    }
}