loop problems/memory problems?

[quakersquares]

I am writing a C++ program for class, I am fairly new to C++ but have plenty of programming history. I have to split up a integer into an array. but I am having trouble just getting the count for the array!

#include <iomanip>
#include <iostream>
 
using namespace std;
 
class LongInt
{
    public:
        LongInt();
        LongInt(int[], int);
        void print();
        void read();
        LongInt add(LongInt);
        void setLength(int);
        void createIntArray(int);
        int getLength();
    private:
        int *a;
        int length;
};
 
LongInt::LongInt()
{
 
}
 
LongInt LongInt::add(LongInt other)
{
    int firstIntLength = length;
    int secondIntLength = other.length;
    int resultIntLength;
 
    if(firstIntLength> secondIntLength) 
        resultIntLength = firstIntLength + 1;
    else resultIntLength = secondIntLength + 1;
 
    LongInt result;
    result.a = new int[resultIntLength];
    result.length = resultIntLength;
 
    int carry = 0;
    int p1 = firstIntLength -1;
    int p2 = secondIntLength -1;
    int p3 = resultIntLength -1;
 
    for( int i = resultIntLength - 3 ; i>0 ; i-- )
    {
        result.a[p3] = a[p3] + carry;
        if( p1 >= 0 )
        {
            result.a[p3] = result.a[p3] + a[p1];
            p1--;
        }
        if(p2>=0)
        {
            result.a[p3] = result.a[p3] + other.a[p2];
            p2--;
        }
        carry = (result.a[p3]/10);
        result.a[p3] = (result.a[p3])%10;
        p3--;
    }
    result.a[p3] = carry;
    return result;
}
 
void LongInt::setLength(int intLength)
{
    length = intLength;
}  
 
int LongInt::getLength()
{
    return length;
}
 
void LongInt::read()
{
    unsigned long int number;
    int remainder;
    int lengthcount = 0;
 
    cin >> number;
 
    unsigned long int newnumber = number;
 
    while( newnumber >= 1 ) 
    {            
        lengthcount++;
 
        newnumber = newnumber/10;
 
        cout << newnumber << endl;
    }
 
    cout << lengthcount << endl;
 
    a = new int(lengthcount);
 
    for( int i = lengthcount-1 ; i >= 0 ; i-- )
    {
        remainder = number%10;
        number = number/10;
 
        a[i] = remainder;
        cout << a[i] << endl;
    }
    setLength(lengthcount);
}
 
void LongInt::print()
{
    for( int i = 0 ; i < getLength() ; i++)
        cout << a[i];
    cout << endl;
}
int main()
{
    LongInt I1, I2, I3;
 
    I1.read();
    //I2.read();
 
    //I3 = I2.add(I1);
 
    I1.print();
    //I2.print();
    //I3.print();
 
    return 0;
}

it works fine for numbers with 10 or less digits. Once I put in a digit of 11 or more (not mattering what the digit is. goes all to hell... The program isnt done, but I am stuck here and cant figure out why. Any help is much appreciated. I am on Mint Linux using G++

if I put in 1111111111 it will put out 1111111111
if I put in 11111111111 it will put out 3086772644

it will always put out that number. if i change it to an unsigned long int. it puts out the same number. long int does that same number also.

[JosAH]

if I put in 1111111111 it will put out 1111111111
if I put in 11111111111 it will put out 3086772644

it will always put out that number. if i change it to an unsigned long int. it puts out the same number. long int does that same number also.

I guess all your (unsigned) int types are four bytes long; 11111111111 is larger
than 2^32-1. 1111111111 (ten ones) do fit in a four byte int.

kind regards,

Jos

[quakersquares]

so its just a memory issue? not even an unsigned long int wont hold the a that large?

[JosAH]

so its just a memory issue? not even an unsigned long int wont hold the a that large?

Yup; 32 bits can just hold numbers in the range [0, 2^32) or any equivalent range
but that's just our interpretation thereof, e.g. signed ints mean [-2^31, 2^31) to us.

kind regards,

Jos

[quakersquares]

thanks man, I appreciate it