glibc detected error, possible memory leak? - c++

Question

Header File (IntegerSet.h)
#include<iostream>
#include<string>
using namespace std;
class IntegerSet{
public:
unsigned int set[15];
unsigned int empty_set[15];
IntegerSet();
IntegerSet(int[],int);
IntegerSet unionOfsets(IntegerSet);
IntegerSet intersectionOfSets(IntegerSet);
void insertElement(int);
void deleteElement(int);
void printSet();
bool isEqualTo(IntegerSet);
void emptySet();//Set all elements of set to 0
void inputSet();//Reads values from the user into set
bool validEntry(int);//Determines a valid entry to the set
};
Implementation File (IntegerSet.cpp)
//Class implementation file
#include "IntegerSet.h"
using namespace std;
IntegerSet::IntegerSet(){
for(int i=0;i<100;i++){
empty_set[i]=0;
}
}
IntegerSet::IntegerSet(int arr[],int size){
int min;//Use to hold the value for the sorting algorithm
int counter;//Used to count how many values need to be removed from the new array
for(int i=0;i<size-1;i++){//Nested for loop used to sort the array in ascending order
min=arr[i];
if(arr[i]<0||arr[i]>100){//If statement used to count how many numbers are <0 or >100
counter++;
}
for(int k=i+1;k<size;k++){
if(arr[k]<min){
arr[i]=arr[k];
arr[k]=min;
min=arr[i];
}
}
}
int *newSet=new int[size-counter];
for(int j=0;j<size;j++){
if(arr[j]>100||arr[j]<0){
//Do nothing
}else{
newSet[j]=arr[j];
}
}
delete newSet;
}
bool IntegerSet::validEntry(int a){
if(a<0||a>100){
return false;
}
return true;
}
void IntegerSet::inputSet(){
int a;
for(int i=0;i<100;i++){
cout<<"Enter an element(-1 to end)";
cin>>a;
if(a==-1){
cout<<"Entry complete";
return;
}
this->set[i]=a;
}
}
void IntegerSet::emptySet(){
for(unsigned int i=0;i<sizeof(this->set);i++){
this->set[i]=0;
}
}
IntegerSet IntegerSet::unionOfsets(IntegerSet a){
unsigned int *Union=new unsigned int[sizeof(this->set)+sizeof(a.set)];
for(unsigned int i=0;i<sizeof(this->set);i++){
*(Union+i)=this->set[i];
for(unsigned int h=0;h<sizeof(this->set);h++){
*(Union+(h+i))=a.set[h];
}
}
for(unsigned int j=0;j<sizeof(*Union);j++){
for(unsigned int z=j+1;z<sizeof(*Union);z++){
if(*(Union+j)==*(Union+z)){
*(Union+z)=0;
}
}
}
unsigned int newUnion[sizeof(*Union)];
for(unsigned int y=0;y<sizeof(*Union);y++){
if(*(Union+y)!=0&&y<sizeof(newUnion)){
newUnion[y]=*(Union+y);
}
}
IntegerSet c;
for(unsigned int w=0;w<sizeof(*Union);w++){
c.set[w]=newUnion[w];
}
delete Union;
return c;
}
IntegerSet IntegerSet::intersectionOfSets(IntegerSet a){
unsigned int *Intersect=new unsigned int[sizeof(this->set)+sizeof(a.set)];
int counter=0;
for(unsigned int i=0;i<sizeof(this->set);i++){
for(unsigned int j=0;j<sizeof(a.set);j++){
if(this->set[i]==a.set[j]){
*(Intersect+counter)=a.set[j];
counter++;
}
}
}
IntegerSet c;
for(unsigned int w=0;w<sizeof(*Intersect);w++){
c.set[w]=*(Intersect+w);
}
delete Intersect;
return c;
}
void IntegerSet::printSet(){
unsigned int min;
for(unsigned int i=0;i<sizeof(this->set)-1;i++){
min=this->set[i];
for(unsigned int k=i+1;k<sizeof(this->set);k++){
{
if(this->set[k]<min){
this->set[i]=this->set[k];
this->set[k]=min;
min=this->set[i];
}
}
}
cout<<"{";
for(unsigned int h=0;h<3;h++){
if(h==sizeof(this->set)-1){
cout<<this->set[h]<<"}";
}else{
cout<<this->set[h]<<",";
}
}
}
bool IntegerSet::isEqualTo(IntegerSet a){
unsigned int counter=0;
if(sizeof(a.set)==sizeof(this->set)){
for(unsigned int i=0;i<sizeof(this->set);i++){
for(unsigned int f=0;f<sizeof(a.set);f++){
if(this->set[i]==a.set[f]){
counter++;
}
}
}
}else{
return false;
}
if(counter==sizeof(this->set)){
return true;
}
return false;//Used to make sure this method always has something to return
}
void IntegerSet::insertElement(int a){
unsigned A=(unsigned)a;
if(!this->validEntry(a)){
cout<<"Invalid Insertion Attempt!";
}
unsigned int Inserted[sizeof(this->set)+1];
Inserted[sizeof(this->set)]=A;
for(unsigned int w=0;w<sizeof(Inserted);w++){
this->set[w]=Inserted[w];
}
}
void IntegerSet::deleteElement(int a){
unsigned A=(unsigned) a;
unsigned int *Delete=new unsigned int[sizeof(this->set)-1];int test=0;
if(!this->validEntry(a)){
cout<<"No value of: "<<a<<" exists in the set";
}
for(unsigned int z=0;z<sizeof(this->set);z++){
if(this->set[z]==A){
test++;
}
}
if(test==0){
cout<<"No value of: "<<a<<" exists in the set";
}
for(unsigned int i=0;i<sizeof(this->set)-1;i++){
*(Delete+i)=this->set[i];
}
for(unsigned int w=0;w<sizeof(*Delete);w++){
this->set[w]=*(Delete+w);
}
delete Delete;
}
And then there is my tester file, which is what allowed me to find the error
(IntSet.cpp)
//Driver program for class IntegerSet
#include <iostream>
using namespace std;
#include "IntegerSet.h"
int main(){
IntegerSet a,b,c,d;
cout<<"Enter set A:\n";
a.inputSet();
cout<<"\nEnter set B:\n";
b.inputSet();
c=a.unionOfsets(b);
d=a.intersectionOfSets(b);
cout<<"\nUnion of A nd B is:\n";
c.printSet();
cout<<"Intersection of A nd B is:\n";
d.printSet();
//Test if set A is equal to set B
if(a.isEqualTo(b)){
cout<<"Set A is equal to set B\n";
}else{
cout<<"Set A is not equal to set B\n";
}
//test insertion
cout<<"\nInserting 77 into set A...\n";
a.insertElement(77);
cout<<"Set A is now:\n";
a.printSet();
const int arraySize=10;
int intArray[arraySize]={25,67,2,9,99,105,45,-5,100,1};
//Use construct that receive an array of ints
//and the size of that array to create a set object
IntegerSet e(intArray,arraySize);
cout<<"\nSet e is:\n";
e.printSet();
cout<<endl;
}
Personally I feel like what caused this error was some sort of memory leak, although the glib c error isn't exactly telling me where it would be coming from like the compiler does. Also this error occurs right after the function b.inputSet() exits.
What the error says (it alternates between two messages I've noticed):
***glibc detected*** ./a.out: free(): invalid next size (normal):
***glibc detected*** ./a.out: double free or corruption (!prev):

Answer 1

You're doing lots of bad here.
Here's your definition of empty_set.
unsigned int empty_set[15];
And your default constructor accesses outside these bounds.
IntegerSet::IntegerSet(){
for(int i=0;i<100;i++){
empty_set[i]=0;
}
}
Your other constructor doesn't actually change anything inside the class.
Also this code
IntegerSet IntegerSet::unionOfsets(IntegerSet a){
unsigned int *Union=new unsigned int[sizeof(this->set)+sizeof(a.set)];
looks remarkably suspicious as sizeof(set) is not the number of elements in set, but the array length in bytes (15*sizeof(float)) - but if you switch to a variable length array it wont even be that... You'll need to track the set length separately. Or use a std::vector<int>, or better yet - why reinvent the wheel and use std::set<int>?