Problems in managing Memory-leaks C++ [closed] - c++

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I'm not getting any errors or something like this, but the problem is that no matter what I do, I can't get rid of those memory-leaks. The only solution that i found that helps me is to add delete[] vector1 after every method but I'm not allowed to modify that part of the code.
In the code you can see the comments and the areas where I can add new instructions. Is there any solution to my problem?
THIS IS THE CODE:
#include<iostream>
using namespace std;
/*YOU CAN'T ADD NEW METHODS*/
/*YOU CAN ONLY MODIFY THE BODY OF THE METHODS*/
//read array from the console - number of elements and the elements
int * readVectorVersion1(int * noElements) {
int *vector1;
vector1 = new int[*noElements + 1];
for (int i = 0; i < *noElements; i++)
{
cout << endl << "Vector1[" << i + 1 << "]=";
cin >> vector1[i];
}
return vector1;
}
//read array from the console - number of elements and the elements
void readVectorVersion2(int ** vector, int* noElements) {
*vector = new int[*noElements + 1];
for (int i = 0; i < *noElements; i++)
{
cout << endl << "Vector1[" << i + 1 << "]=";
cin >> (*vector)[i];
}
}
//read array from the console - number of elements and the elements
void readVectorVersion3(int *& vector, int& noElements) {
vector = new int[noElements + 1];
for (int i = 0; i < noElements; i++)
{
cout << endl << "Vector1[" << i + 1 << "]=";
cin >> vector[i];
}
}
//read array from the console - number of elements and the elements
int * readVectorVersion4(int& noElements) {
int *vector1;
vector1 = new int[noElements + 1];
for (int i = 0; i < noElements; i++)
{
cout << endl << "Vector1[" << i + 1 << "]=";
cin >> vector1[i];
}
return vector1;
}
//read static array from the console - number of elements and the elements
void readStaticVector(int vector[], int * noElements) {
for (int i = 0; i < *noElements; i++)
{
cout << endl << "Vector1[" << i + 1 << "]=";
cin >> vector[i];
}
}
//print the elements of the array
void afisareVector(int* vector, int noElements) {
cout << endl << "Vector:" << endl;
for (int i = 0; i < noElements; i++)
cout << vector[i] << " ";
}
//read a name from the console
char* citesteNume() {
char temp[200];
char * nume;
cout << endl << "Your name:";
cin >> temp;
nume = new char[strlen(temp) + 1];
strcpy(nume, temp);
return nume;
}
//read a name from the console
void citesteNume(char* nume) {
cout << endl << "Your name:";
cin >> nume;
}
//METHODS THAT ADDS AN ELEMENT (THAT IS GIVEN) TO AN EXISTING ARRAY
//FIRST
void adaugaElementNou(int** vector, int* noElemente, int elementNou) {
(*vector) = new int[*noElemente + 2];
for (int i = 0; i < *noElemente; i++)
(*vector)[i] = i;
(*vector)[*noElemente] = elementNou;
}
//SECOND
int * adaugaElementNou(int& noElemente, int elementNou) {
int *vector;
vector = new int[noElemente + 2];
for (int i = 0; i < noElemente; i++)
vector[i] = i;
vector[noElemente] = elementNou;
return vector;
}
//THIRD
int * adaugaElementNou(int* noElemente, int elementNou) {
int *vector;
vector = new int[(*noElemente) + 2];
for (int i = 0; i < *noElemente; i++)
vector[i] = i;
vector[*noElemente] = elementNou;
return vector;
}
//THE PROGRAM MUST RUN AND NOT GENERATE ANY ERRORS OR MEMORY-LEAKS
void main() {
//YOU CAN'T ADD NEW VARIABLES
int * vector1;
int vector2[50];
int nrElementeVector1=3;
int nrElementeVector2=3;
//YOU CAN ADD NEW INSTRUCTIONS
// ...
vector1 = new int[nrElementeVector1 + 1];
for (int i = 0; i < nrElementeVector1; i++)
vector1[i] = i;
for (int i = 0; i < nrElementeVector2; i++)
vector2[i] = i;
//YOU CAN'T MODIFY THE FOLLOWING CODE
afisareVector(vector1, nrElementeVector1);
afisareVector(vector2, nrElementeVector2);
//delete[]vector1; /*This instruction is added by me but i`m not allowed to modify this area of the code*/
vector1 = readVectorVersion1(&nrElementeVector1);
afisareVector(vector1, nrElementeVector1);
//delete[]vector1;
readVectorVersion2(&vector1, &nrElementeVector1);
afisareVector(vector1, nrElementeVector1);
//delete[]vector1;
readVectorVersion3(vector1, nrElementeVector1);
afisareVector(vector1, nrElementeVector1);
//delete[]vector1;
vector1 = readVectorVersion4(nrElementeVector1);
afisareVector(vector1, nrElementeVector1);
//delete[]vector1;
readStaticVector(vector2, &nrElementeVector2);
afisareVector(vector2, nrElementeVector2);
char* string1;
char string2[50];
string1 = citesteNume();
cout << endl << "Hello " << string1;
//delete[]string1; /*THIS IS NOT ALLOWED HERE*/
citesteNume(string2);
cout << endl << "Hello " << string2;
vector1 = adaugaElementNou(nrElementeVector1, 99);
afisareVector(vector1, nrElementeVector1+1);
//delete[]vector1;
adaugaElementNou(&vector1, &nrElementeVector1, 55);
afisareVector(vector1, nrElementeVector1+1);
//delete[]vector1;
vector1 = adaugaElementNou(&nrElementeVector1, 77);
afisareVector(vector1, nrElementeVector1+1);
//delete[]vector1;
//YOU CAN ADD NEW INSTRUCTIONS HERE
// ...
delete[] vector1; //I`ve tried to use delete here because I didn`t knew what else i should do, but I know that it makes no sense(and it`s not working);
delete[] string1;
//THE FOLLOWING CODE CHECKS IF THERE ARE ANY MEMORYLEAKS
_CrtSetReportMode(_CRT_WARN, _CRTDBG_MODE_FILE);
_CrtSetReportFile(_CRT_WARN, _CRTDBG_FILE_STDOUT);
_CrtSetReportMode(_CRT_ERROR, _CRTDBG_MODE_FILE);
_CrtSetReportFile(_CRT_ERROR, _CRTDBG_FILE_STDOUT);
_CrtSetReportMode(_CRT_ASSERT, _CRTDBG_MODE_FILE);
_CrtSetReportFile(_CRT_ASSERT, _CRTDBG_FILE_STDOUT);
_CrtDumpMemoryLeaks();
//YOU CAN'T MODIFY THE FOLLOWING CODE
vector1 = NULL;
string1 = NULL;
cout << endl << "In this moment there are no memory-leaks!";
}

Answer 1

For string1 it's simple, you can just:
delete[] string1;
And this is what I think you are supposed to do deal with vector1:
void afisareVector(int* vector, int noElements) {
cout << endl << "Vector:" << endl;
for (int i = 0; i < noElements; i++)
cout << vector[i] << " ";
// A very dirty hack, PLEASE **NEVER** USE IT.
static int callIndex = 0;
if(callIndex != 1 && callIndex != 6)
delete[] vector;
++callIndex;
}
valgrind summary:
==20937== HEAP SUMMARY:
==20937== in use at exit: 0 bytes in 0 blocks
==20937== total heap usage: 9 allocs, 9 frees, 144 bytes allocated
==20937==
==20937== All heap blocks were freed -- no leaks are possible
==20937==
==20937== For counts of detected and suppressed errors, rerun with: -v
==20937== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
Edit: I changed my mind. The example above is what you can do and this is what you are supposed to do:
Note #1: this hack feels even dirtier to me.
Note #2: In order to compile it, I had to remove all Microsoft-specific stuff and perform a leak checking with the valgrind.
#include<iostream>
#include<cstring>
using namespace std;
/*YOU CAN'T ADD NEW METHODS*/
/*YOU CAN ONLY MODIFY THE BODY OF THE METHODS*/
//read array from the console - number of elements and the elements
int * readVectorVersion1(int * noElements) {
static int vector1[50];
for (int i = 0; i < *noElements; i++)
{
cout << endl << "Vector1[" << i + 1 << "]=";
cin >> vector1[i];
}
return vector1;
}
//read array from the console - number of elements and the elements
void readVectorVersion2(int ** vector1, int* noElements) {
static int vector [50];
for (int i = 0; i < *noElements; i++)
{
cout << endl << "Vector1[" << i + 1 << "]=";
cin >> vector[i];
}
*vector1 = vector;
}
//read array from the console - number of elements and the elements
void readVectorVersion3(int *& vector1, int& noElements) {
static int vector [50];
for (int i = 0; i < noElements; i++)
{
cout << endl << "Vector1[" << i + 1 << "]=";
cin >> vector[i];
}
vector1 = vector;
}
//read array from the console - number of elements and the elements
int * readVectorVersion4(int& noElements) {
static int vector1 [50];
for (int i = 0; i < noElements; i++)
{
cout << endl << "Vector1[" << i + 1 << "]=";
cin >> vector1[i];
}
return vector1;
}
//read static array from the console - number of elements and the elements
void readStaticVector(int vector[], int * noElements) {
for (int i = 0; i < *noElements; i++)
{
cout << endl << "Vector1[" << i + 1 << "]=";
cin >> vector[i];
}
}
//print the elements of the array
void afisareVector(int* vector, int noElements) {
cout << endl << "Vector:" << endl;
for (int i = 0; i < noElements; i++)
cout << vector[i] << " ";
}
//read a name from the console
char* citesteNume() {
char temp[200];
char * nume;
cout << endl << "Your name:";
cin >> temp;
nume = new char[strlen(temp) + 1];
strcpy(nume, temp);
return nume;
}
//read a name from the console
void citesteNume(char* nume) {
cout << endl << "Your name:";
cin >> nume;
}
//METHODS THAT ADDS AN ELEMENT (THAT IS GIVEN) TO AN EXISTING ARRAY
//FIRST
void adaugaElementNou(int** vector, int* noElemente, int elementNou) {
static int vector1 [50];
for (int i = 0; i < *noElemente; i++)
vector1[i] = i;
vector1[*noElemente] = elementNou;
*vector = vector1;
}
//SECOND
int * adaugaElementNou(int& noElemente, int elementNou) {
static int vector [50];
for (int i = 0; i < noElemente; i++)
vector[i] = i;
vector[noElemente] = elementNou;
return vector;
}
//THIRD
int * adaugaElementNou(int* noElemente, int elementNou) {
static int vector [50];
for (int i = 0; i < *noElemente; i++)
vector[i] = i;
vector[*noElemente] = elementNou;
return vector;
}
//THE PROGRAM MUST RUN AND NOT GENERATE ANY ERRORS OR MEMORY-LEAKS
int main() {
//YOU CAN'T ADD NEW VARIABLES
int * vector1;
int vector2[50];
int nrElementeVector1=3;
int nrElementeVector2=3;
//YOU CAN ADD NEW INSTRUCTIONS
for (int i = 0; i < nrElementeVector2; i++)
vector2[i] = i;
vector1 = vector2;
//YOU CAN'T MODIFY THE FOLLOWING CODE
afisareVector(vector1, nrElementeVector1);
afisareVector(vector2, nrElementeVector2);
vector1 = readVectorVersion1(&nrElementeVector1);
afisareVector(vector1, nrElementeVector1);
readVectorVersion2(&vector1, &nrElementeVector1);
afisareVector(vector1, nrElementeVector1);
readVectorVersion3(vector1, nrElementeVector1);
afisareVector(vector1, nrElementeVector1);
vector1 = readVectorVersion4(nrElementeVector1);
afisareVector(vector1, nrElementeVector1);
readStaticVector(vector2, &nrElementeVector2);
afisareVector(vector2, nrElementeVector2);
char* string1;
char string2[50];
string1 = citesteNume();
cout << endl << "Hello " << string1;
citesteNume(string2);
cout << endl << "Hello " << string2;
vector1 = adaugaElementNou(nrElementeVector1, 99);
afisareVector(vector1, nrElementeVector1+1);
adaugaElementNou(&vector1, &nrElementeVector1, 55);
afisareVector(vector1, nrElementeVector1+1);
vector1 = adaugaElementNou(&nrElementeVector1, 77);
afisareVector(vector1, nrElementeVector1+1);
//YOU CAN ADD NEW INSTRUCTIONS HERE
// ...
delete[] string1;
//YOU CAN'T MODIFY THE FOLLOWING CODE
vector1 = NULL;
string1 = NULL;
}
valgrind output:
==21224== HEAP SUMMARY:
==21224== in use at exit: 0 bytes in 0 blocks
==21224== total heap usage: 1 allocs, 1 frees, 2 bytes allocated
==21224==
==21224== All heap blocks were freed -- no leaks are possible
==21224==
==21224== For counts of detected and suppressed errors, rerun with: -v
==21224== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
Edit: I came up with the 3rd (even dirtier) solution, but I'm too tired of all this hacking to write a complete version. Here is an example:
int * readVectorVersion1(int * noElements) {
static int *vector1 = NULL;
delete[] vector1;
if (noElements < 0)
return NULL;
vector1 = new int[*noElements + 1];
for (int i = 0; i < *noElements; i++)
{
cout << endl << "Vector1[" << i + 1 << "]=";
cin >> vector1[i];
}
return vector1;
}
// ...
int main() {
// ...
// Just before _CrtSetReportMode
nrElementeVector1 = -1;
readVectorVersion1(*nrElementeVector1);
// ..
}

Answer 2

I'd say this task is impossible to accomplish. The line
vector1 = readVectorVersion1(&nrElementeVector1);
is executed when vector1 holds a dynamically allocated resource. Creating an unrecoverable leak at this point. The same goes for the following
readVectorVersion2(&vector1, &nrElementeVector1);

Answer 3

The vector1 pointer is overwritten in the code that you may not modify, so clearly it may not be the only pointer to dynamically allocated memory, or else it will leak and there is nothing you can do to stop that, within the restraints of your assignment.
So, let's explore the possibility of using a static object to hold the pointer. I'll use std::vector for simplicity, but you can use a static pointer to dynamic memory if you want to. In that case you'll need to manage the memory manually.
int * readVectorVersion1(int * noElements) {
static std::vector<int> vector1;
vector1.resize(*noElements);
// initialize the way you want to
return vector1.data();
// return &vector1[0]; // use this if you use older version of c++ than c++11
}
And there you go. The memory will be deallocated when static objects are destroyed. This of course does limit what you can do with the function. You can no longer allocate two separate arrays because subsequent calls will use the same vector. But it's not needed for this assignment, so I guess this is what your instructor is asking for.