Undefined errors with arrays in c++? - c++

Question

Basically we're trying to make arrays accessible at irregular indexes with this new object IntArray, we have a couple header and .cpp files, take a look:
//intarray.h
#ifndef _IntArray_H
#define _IntArray_H
#include <iostream>
#include <string>
using namespace std;
class IntArray {
public:
IntArray(int n);
IntArray(int a, int b);
IntArray();
IntArray(const IntArray& copyarray);
int low();
int high();
void setName(string n);
int *array;
int size;
void operator+=(IntArray&);
int& operator[](int x);
IntArray& operator=(IntArray&);
int operator!=(IntArray&);
int operator==(IntArray&);
friend ostream& operator<<(ostream&, const IntArray&);
friend IntArray operator+(IntArray& a, IntArray& b);
private:
//PRIVATE DATA MEMBERS
int lo, hi;
string name;
};
#endif
Here is the next file, another header file
// iadrv.h
#ifndef _IADRV_H
#define _IADRV_H
#include "intarray.h"
int main();
void test1();
void test2();
void test3();
void test4();
void test5();
void test6();
void test7();
void test8();
void test9();
void test10();
void test11();
void test12();
void test13();
void test14();
void test15();
void test16();
void test17();
void test18();
void test19();
void test20();
void wait();
#endif
and lastly, here are the two .cpp files
//intarray.cpp
#include <iostream>
#include <fstream>
#include "IntArray.h"
#include <string>
extern ofstream csis;
using namespace std;
IntArray::IntArray() {
size = 10;
array = new int[size];
lo = 0;
hi = (size - 1);
}
IntArray::IntArray(int n) {
array = new int[n];
lo = 0;
hi = n - 1;
size = n;
}
IntArray::IntArray(int a, int b) {
if (b > a) {
size = (b - a) + 1;
array = new int[size];
lo = a;
hi = b;
}
if (b == a) {
size = 1;
array = new int[size];
lo = a;
hi = b;
}
else if (a > b) {
cout << "-ERROR: First argument cannot be larger than second argument. Program Halted-" << endl;
}
}
IntArray::IntArray(const IntArray& copyarray) {
IntArray::lo = copyarray.lo;
IntArray::hi = copyarray.hi;
IntArray::size = copyarray.size;
array = new int[size];
for (int i = lo; i <= hi; i++) {
array[i] = copyarray.array[i];
}
}
ostream& operator<<(ostream& ostr, const IntArray& target)
{
int offset = target.lo;
for (int i = target.lo; i <= target.hi; i++) {
ostr << target.name << "[" << i << "] = " << target.array[i] << endl;
}
return ostr;
}
void IntArray::operator+=(IntArray& target)
{
int* p1 = (target.array + target.lo);
if ((hi - lo) != (target.hi - target.lo)) {
cout << "-ERROR: For +=, both elements must have same # of elements. Program Halted-" << endl;
csis << "-ERROR: For +=, both elements must have same # of elements. Program Halted-" << endl;
}
else {
for (int i = lo; i <= hi; i++) {
array[i] = *(p1 + i) + *(array + i);
}
}
}
IntArray operator+(IntArray& tar1, IntArray& tar2)
{
IntArray sum(tar1.size);
int* p1, *p2;
p1 = (tar1.array + tar1.lo);
p2 = (tar2.array + tar2.lo);
if (!(tar1.size == tar2.size)) {
cout << "-ERROR: To use +, must have same # of elements. Program Halted-" << endl << endl;
csis << "-ERROR: To use +, must have same # of elements. Program Halted-" << endl << endl;
}
else {
for (int i = 0; i <= sum.size; i++) {
sum.array[i] = *(p1 + i) + *(p2 + i);
}
}
return IntArray(sum);
}
int& IntArray::operator[](int x)
{
/**
if (x < lo) {
cout << "-ERROR: Not in range. Program Halt-" << endl << endl;
csis << "-ERROR: Not in range. Program Halt-" << endl << endl;
}
if (x > hi) {
cout << "-ERROR: Not in range. Program Halt-" << endl << endl;
csis << "-ERROR: Not in range. Program Halt-" << endl << endl;
}
*/
return array[x];
}
int IntArray::operator!=(IntArray& target)
{
int difference = target.lo - IntArray::lo;
int check = 1;
if ((size) == (target.size)) {
for (int i = lo; i <= hi; i++) {
if (array[i] == target.array[i + difference]) {
check--;
}
}
}
else if (size != target.size) {
return check;
}
if (check < 0) {
check = 0;
}
return check;
}
int IntArray::operator==(IntArray& target)
{
int check = 0;
int difference = target.lo - IntArray::lo;
if (size == target.size) {
for (int i = lo; i <= hi; i++) {
if (array[i] == target.array[i + difference]) {
check++;
}
}
}
else if (!(size == target.size)) {
return 0;
}
if (check > 0) {
check = 1;
}
return check;
}
IntArray& IntArray::operator=(IntArray& target)
{
int difference = target.lo - IntArray::lo;
if (size != target.size) {
cout << "ERROR: Invalid assigment of two different sized arrays" << endl << endl << endl;
csis << "ERROR: Invalid assigment of two different sized arrays" << endl << endl << endl;
}
for (int i = IntArray::lo; i <= IntArray::hi; i++) {
array[i] = target.array[i + difference];
}
return *this;
}
void IntArray::setName(string n) {
IntArray::name = n;
}
int IntArray::low() {
return lo;
}
int IntArray::high() {
return hi;
}
This is the .cpp file with main
// iadrv.cpp - driver program for testing IntArray class
#include <iostream>
#include <iomanip>
#include <fstream>
#include <stdlib.h>
#include "iadrv.h"
using namespace std;
ofstream csis;
int main() {
csis.open("csis.txt");
test1();
test2();
test3();
/**
test4();
test5();
test6();
test7();
test8();
test9();
test10();
test11();
test12();
test13();
test14();
test15();
test16();
test17();
test18();
test19();
test20();
*/
csis.close();
}
void test1() {
cout << "1. Array declared with single integer: IntArray a(10);" << endl << endl;
csis << "1. Array declared with single integer: IntArray a(10);" << endl << endl;
IntArray a(10);
for (int i = a.low(); i <= a.high(); i++)
a[i] = i * 10;
a.setName("a");
cout << a << endl;
csis << a << endl;
wait();
}
void test2() {
cout << "2. Array declared with two integers: IntArray b(-3, 6);" << endl << endl;
csis << "2. Array declared with two integers: IntArray b(-3, 6);" << endl << endl;
IntArray b(-3, 6);
for (int i = b.low(); i <= b.high(); i++)
b[i] = i * 10;
b.setName("b");
cout << b << endl;
csis << b << endl;
wait();
}
void test3() {
cout << "3. Array declared with two integers: IntArray c(6, 8);" << endl << endl;
csis << "3. Array declared with two integers: IntArray c(6, 8);" << endl << endl;
IntArray c(6, 8);
cout << c.low() << endl;
cout << c.high() << endl;
for (int i = c.low(); i <= c.high(); i++) {
c[i] = i * 10;
cout << c[i] << " " << i << endl;
}
c.setName("c");
cout << c << endl;
csis << c << endl;
wait();
}
void test4() {
cout << "4. Array declared with two identical integers: IntArray d(5, 5);" << endl << endl;
csis << "4. Array declared with two identical integers: IntArray d(5, 5);" << endl << endl;
IntArray d(5, 5);
for (int i = d.low(); i <= d.high(); i++)
d[i] = i * 10;
d.setName("d");
cout << d << endl;
csis << d << endl;
wait();
}
void test5() {
cout << "5. Array declared with no integers: IntArray z;" << endl << endl;
csis << "5. Array declared with no integers: IntArray z;" << endl << endl;
IntArray z;
for (int i = z.low(); i <= z.high(); i++)
z[i] = i * 10;
z.setName("z");
cout << z << endl;
csis << z << endl;
wait();
}
void test6() {
cout << "6. Array declared with another object of type IntArray: IntArray c(6, 8);" << endl;
cout << " Intarray e(c);" << endl << endl;
csis << "6. Array declared with another object of type IntArray: IntArray c(6, 8);" << endl;
csis << " Intarray e(c);" << endl << endl;
IntArray c(6, 8);
for (int i = c.low(); i <= c.high(); i++)
c[i] = i * 10;
c.setName("c");
cout << c << endl;
csis << c << endl;
IntArray e(c);
e.setName("e");
cout << e << endl;
csis << e << endl;
wait();
}
void test7() {
cout << "7. Array assigned to another array w/ different indices: IntArray f(1, 4);" << endl;
cout << " IntArray g(5, 8);" << endl;
cout << " f = g;" << endl << endl;
csis << "7. Array assigned to another array w/ different indices: IntArray f(1, 4);" << endl;
csis << " IntArray g(5, 8);" << endl;
csis << " f = g;" << endl << endl;
IntArray f(1, 4);
for (int i = f.low(); i <= f.high(); i++)
f[i] = i * 10;
f.setName("f");
cout << f << endl;
csis << f << endl;
IntArray g(5, 8);
for (int i = g.low(); i <= g.high(); i++)
g[i] = i * 10;
g.setName("g");
cout << g << endl;
csis << g << endl;
wait();
f = g;
cout << f << endl;
cout << g << endl;
csis << f << endl;
csis << g << endl;
wait();
}
void test8() {
cout << "8. Multiple array assignment with different indices: IntArray j(3, 6);" << endl;
cout << " IntArray k(6, 9);" << endl;
cout << " IntArray l(1, 4);" << endl;
cout << " j = k = l;" << endl << endl;
csis << "8. Multiple array assignment with different indices: IntArray j(3, 6);" << endl;
csis << " IntArray k(6, 9);" << endl;
csis << " IntArray l(1, 4);" << endl;
csis << " j = k = l;" << endl << endl;
IntArray j(3, 6);
for (int i = j.low(); i <= j.high(); i++)
j[i] = i * 10;
j.setName("j");
cout << j << endl;
csis << j << endl;
IntArray k(6, 9);
for (int i = k.low(); i <= k.high(); i++)
k[i] = i * 10;
k.setName("k");
cout << k << endl;
csis << k << endl;
IntArray l(1, 4);
for (int i = l.low(); i <= l.high(); i++)
l[i] = i * 10;
l.setName("l");
cout << l << endl;
csis << l << endl;
wait();
j = k = l;
cout << j << endl;
cout << k << endl;
cout << l << endl;
csis << j << endl;
csis << k << endl;
csis << l << endl;
wait();
}
void test9() {
cout << "9. Overloaded equality operator (identical elements): IntArray m(3, 7);" << endl;
cout << " IntArray n(1, 5);" << endl;
cout << " m == n" << endl << endl;
csis << "9. Overloaded equality operator (identical elements): IntArray m(3, 7);" << endl;
csis << " IntArray n(1, 5);" << endl;
csis << " m == n" << endl << endl;
IntArray m(3, 7);
for (int i = m.low(); i <= m.high(); i++)
m[i] = i * 10;
m.setName("m");
cout << m << endl;
csis << m << endl;
IntArray n(1, 5);
for (int i = n.low(); i <= n.high(); i++)
n[i] = i * 10;
n.setName("n");
cout << n << endl;
csis << n << endl;
wait();
m = n;
cout << m << endl;
cout << n << endl;
cout << "Returns " << (m == n ? "True." : "False.") << endl << endl;
csis << m << endl;
csis << n << endl;
csis << "Returns " << (m == n ? "True." : "False.") << endl << endl;
wait();
}
void test10() {
cout << "10. Overloaded equality operator (different elements): IntArray o(3, 7);" << endl;
cout << " IntArray p(1, 5);" << endl;
cout << " o == p" << endl << endl;
csis << "10. Overloaded equality operator (different elements): IntArray o(3, 7);" << endl;
csis << " IntArray p(1, 5);" << endl;
csis << " o == p" << endl << endl;
IntArray o(3, 7);
for (int i = o.low(); i <= o.high(); i++)
o[i] = i * 10;
o.setName("o");
cout << o << endl;
csis << o << endl;
IntArray p(1, 5);
for (int i = p.low(); i <= p.high(); i++)
p[i] = i * 10;
p.setName("p");
cout << p << endl;
cout << "Returns " << (o == p ? "True." : "False.") << endl << endl;
csis << p << endl;
csis << "Returns " << (o == p ? "True." : "False.") << endl << endl;
wait();
}
void test11() {
cout << "11. Overloaded equality operator (different size arrays): IntArray q(1, 3);" << endl;
cout << " IntArray r(1, 4);" << endl;
cout << " q == r;" << endl << endl;
csis << "11. Overloaded equality operator (different size arrays): IntArray q(1, 3);" << endl;
csis << " IntArray r(1, 4);" << endl;
csis << " q == r;" << endl << endl;
IntArray q(1, 3);
for (int i = q.low(); i <= q.high(); i++)
q[i] = i * 10;
q.setName("q");
cout << q << endl;
csis << q << endl;
IntArray r(1, 4);
for (int i = r.low(); i <= r.high(); i++)
r[i] = i * 10;
r.setName("r");
cout << r << endl;
cout << "Returns " << (q == r ? "True." : "False.") << endl << endl;
csis << r << endl;
csis << "Returns " << (q == r ? "True." : "False.") << endl << endl;
wait();
}
void test12() {
cout << "12. Overloaded inequality operator (identical elements): IntArray s(3, 7);" << endl;
cout << " IntArray t(1, 5);" << endl;
cout << " s != t;" << endl << endl;
csis << "12. Overloaded inequality operator (identical elements): IntArray s(3, 7);" << endl;
csis << " IntArray t(1, 5);" << endl;
csis << " s != t;" << endl << endl;
IntArray s(3, 7);
for (int i = s.low(); i <= s.high(); i++)
s[i] = i * 10;
s.setName("s");
cout << s << endl;
csis << s << endl;
IntArray t(1, 5);
for (int i = t.low(); i <= t.high(); i++)
t[i] = i * 10;
t.setName("t");
cout << t << endl;
csis << t << endl;
wait();
s = t;
cout << s << endl;
cout << t << endl;
cout << "Returns " << (s != t ? "True." : "False.") << endl << endl;
csis << s << endl;
csis << t << endl;
csis << "Returns " << (s != t ? "True." : "False.") << endl << endl;
wait();
}
void test13() {
cout << "13. Overloaded inequality operator (different elements): IntArray u(3, 7);" << endl;
cout << " IntArray v(1, 5);" << endl;
cout << " u != v;" << endl << endl;
csis << "13. Overloaded inequality operator (different elements): IntArray u(3, 7);" << endl;
csis << " IntArray v(1, 5);" << endl;
csis << " u != v;" << endl << endl;
IntArray u(3, 7);
for (int i = u.low(); i <= u.high(); i++)
u[i] = i * 10;
u.setName("u");
cout << u << endl;
csis << u << endl;
IntArray v(1, 5);
for (int i = v.low(); i <= v.high(); i++)
v[i] = i * 10;
v.setName("v");
cout << v << endl;
cout << "Returns " << (u != v ? "True." : "False.") << endl << endl;
csis << v << endl;
csis << "Returns " << (u != v ? "True." : "False.") << endl << endl;
wait();
}
void test14() {
cout << "14. Overloaded inequality operator (different size arrays): IntArray w(1, 3);" << endl;
cout << " IntArray x(1, 4);" << endl;
cout << " w != x;" << endl << endl;
csis << "14. Overloaded inequality operator (different size arrays): IntArray w(1, 3);" << endl;
csis << " IntArray x(1, 4);" << endl;
csis << " w != x;" << endl << endl;
IntArray w(1, 3);
for (int i = w.low(); i <= w.high(); i++)
w[i] = i * 10;
w.setName("w");
cout << w << endl;
csis << w << endl;
IntArray x(1, 4);
for (int i = x.low(); i <= x.high(); i++)
x[i] = i * 10;
x.setName("x");
cout << x << endl;
cout << "Returns " << (w != x ? "True." : "False.") << endl << endl;
csis << x << endl;
csis << "Returns " << (w != x ? "True." : "False.") << endl << endl;
wait();
}
void test15() {
cout << "15. Sum of two arrays assigned to third array: IntArray a(1, 5);" << endl;
cout << " IntArray b(4, 8);" << endl;
cout << " IntArray c = a + b;" << endl << endl;
csis << "15. Sum of two arrays assigned to third array: IntArray a(1, 5);" << endl;
csis << " IntArray b(4, 8);" << endl;
csis << " IntArray c = a + b;" << endl << endl;
IntArray a(1, 5);
for (int i = a.low(); i <= a.high(); i++)
a[i] = i * 10;
a.setName("a");
cout << a << endl;
csis << a << endl;
IntArray b(4, 8);
for (int i = b.low(); i <= b.high(); i++)
b[i] = i * 10;
b.setName("b");
cout << b << endl;
csis << b << endl;
wait();
IntArray c = a + b;
c.setName("c");
cout << c << endl;
csis << c << endl;
wait();
}
void test16() {
cout << "16. Sum of two arrays assigned to first array: IntArray d(10, 13);" << endl;
cout << " IntArray e(30, 33);" << endl;
cout << " d += e;" << endl << endl;
csis << "16. Sum of two arrays assigned to first array: IntArray d(10, 13);" << endl;
csis << " IntArray e(30, 33);" << endl;
csis << " d += e;" << endl << endl;
IntArray d(10, 13);
for (int i = d.low(); i <= d.high(); i++)
d[i] = i * 10;
d.setName("d");
cout << d << endl;
csis << d << endl;
IntArray e(30, 33);
for (int i = e.low(); i <= e.high(); i++)
e[i] = i * 10;
e.setName("e");
cout << e << endl;
csis << e << endl;
d += e;
cout << d << endl;
csis << d << endl;
wait();
}
void test17() {
cout << "17. Array declared with illegal array bounds: IntArray f(5, 2);" << endl << endl;
csis << "17. Array declared with illegal array bounds: IntArray f(5, 2);" << endl << endl;
IntArray f(5, 2);
for (int i = f.low(); i <= f.high(); i++)
f[i] = i * 10;
f.setName("f");
cout << f << endl;
csis << f << endl;
wait();
}
void test18() {
cout << "18. Array with index out of range: IntArray g(10);" << endl;
cout << " g[10] = 1;" << endl << endl;
csis << "18. Array with index out of range: IntArray g(10);" << endl;
csis << " g[10] = 1;" << endl << endl;
IntArray g(10);
for (int i = g.low(); i <= g.high(); i++)
g[i] = i * 10;
g.setName("g");
cout << g << endl;
csis << g << endl;
g[10] = 1;
wait();
}
void test19() {
cout << "19. Arrays with length mismatch: IntArray m(1, 4);" << endl;
cout << " IntArray n(2, 4);" << endl;
cout << " m = n;" << endl << endl;
csis << "19. Arrays with length mismatch: IntArray m(1, 4);" << endl;
csis << " IntArray n(2, 4);" << endl;
csis << " m = n;" << endl << endl;
IntArray m(1, 4);
for (int i = m.low(); i <= m.high(); i++)
m[i] = i * 10;
m.setName("m");
cout << m << endl;
csis << m << endl;
IntArray n(2, 4);
for (int i = n.low(); i <= n.high(); i++)
n[i] = i * 10;
n.setName("n");
cout << n << endl;
csis << n << endl;
wait();
m = n;
cout << m << endl;
cout << n << endl;
csis << m << endl;
csis << n << endl;
wait();
}
void test20() {
cout << "20. Array subscript operator: IntArray o(7, 8);" << endl;
cout << " o[7] = 25;" << endl;
cout << " o[8] = o[7];" << endl << endl;
csis << "20. Array subscript operator: IntArray o(7, 8);" << endl;
csis << " o[7] = 25;" << endl;
csis << " o[8] = o[7];" << endl << endl;
IntArray o(7, 8);
for (int i = o.low(); i <= o.high(); i++)
o[i] = i * 10;
o.setName("o");
cout << o << endl;
csis << o << endl;
o[7] = 25;
o[8] = o[7];
cout << o << endl;
csis << o << endl;
wait();
}
void wait() {
char buf;
cout << "Press any key to continue." << endl;
cin.get(buf);
}
The issue is when I try to run and compile in test3(), it'll output correctly SOMETIMES, but other times i'll rebuild the solution and it'll give garbage values despite having same code. It's very odd, and I can't seem to understand why it's doing this

Answer 1

Consider test2, and what happens when you access b[-3]
especially your implementation of int& IntArray::operator[](int x) where you do
int& IntArray::operator[](int x)
{
return array[x];
}
you are returning a reference to bogus memory. (An int that is 3 locations before the beginning of your allocated array)
Modify your code like this:
return array[x-lo];
Oh, and by the way, use std::vector.