How to delete the new array in c++? - c++

Question

I have created a new point function in c++, where I create a new array by Dynamic memory allocation. However, when I want to delete the array in main function, it reports errors like:
'Assessment_1.exe' (Win32): Unloaded 'C:\Windows\SysWOW64\ucrtbased.dll'
'Assessment_1.exe' (Win32): Loaded 'C:\Windows\SysWOW64\ucrtbased.dll'.
The thread 0x22dc has exited with code 0 (0x0).
HEAP[Assessment_1.exe]: Invalid address specified to RtlValidateHeap( 00050000, 0005F25C )
Assessment_1.exe has triggered a breakpoint.
The return_array.cpp contains the function in which user inputs the keyboards.
#include<iostream>
#include <conio.h>
using namespace std;
//const static int length = 3;
int* input() {
//static int number[length]; fixed length for input
static int* number_array;
int number_length = 30;
int index = 0;
number_array = new int[number_length];
cout << "enter (ESC) to escape the program!" << endl;
while (_getch() != 27)
{
cout << "Input your number " << index << " elment: " << endl;
cin >> number_array[index];
index = index + 1;
cout << endl;
}
return number_array;
}
The practice.cpp contains the main function and the evaluation function of two vectors. The bug is when I add the delete []vector_1;.
#include <vector>
#include<iostream>
#include"myFunctions.h"
using namespace std;
const static int length = 3;
bool same_vec(vector<int> a, vector<int> b);
void main() {
vector<int> new_vector_1(length);
vector<int> new_vector_2(length);
int* vector_1 = input();
for (int i = 0; i < length; i++) {
new_vector_1[i] = *vector_1;
cout << *vector_1 << endl;
vector_1 = vector_1 + 1;
}
delete []vector_1;
for (int i = 0; i < length; i++) {
cout << " The result of vector_1: " << new_vector_1[i] << endl;
}
int* vector_2;
vector_2 = input();
for (int i = 0; i < length; i++) {
new_vector_2[i] = *vector_2;
vector_2 = vector_2 + 1;
}
delete []vector_2;
for (int i = 0; i < length; i++) {
cout << " The result of vector_2: " << new_vector_2[i] << endl;
}
bool qax = same_vec(new_vector_1, new_vector_2);
if (qax == false) {
cout << "the items are not match!"<<endl;
}
else {
cout << "the items are match!" << endl;
}
}
bool same_vec(vector<int> a, vector<int> b) {
//Evaluate the elements in the two vectors
bool flag = true;
int length_a = a.size();
int length_b = b.size();
vector<bool> new_bool(length_a);
for (int i = 0; i < length_a; i++) {
for (int j = 0; j < length_b; j++) {
if (a[i] == b[j]) {
new_bool[i] = true;
cout << a[i] << " " << b[j] << endl;
break;
}
}
}
for (int i = 0; i < new_bool.size(); i++) {
if (new_bool[i] == false) {
flag = false;
}
}
return flag;
}
And the myFunction.h is my head file.
#pragma once
int* getRandom();
int* input();
Can someone helps to solve the problem? I know one solution is delete the line of delete []vector_1;. The solution may cause memory-leak.

Answer 1

You are changing the address stored in the vector_1 pointer, then trying to delete[] something that no longer corresponds to the pointer returned by the new operator in your input function.
So, instead of this loop:
for (int i = 0; i < length; i++) {
new_vector_1[i] = *vector_1;
cout << *vector_1 << endl;
vector_1 = vector_1 + 1; // This line changes the pointer!
}
delete []vector_1; // And, here, the pointer is NOT what "new" gave you!
Use something like this, instead:
for (int i = 0; i < length; i++) {
new_vector_1[i] = vector_1[i]; // You can use the [] operator on the pointer
cout << *vector_1 << endl;
// vector_1 = vector_1 + 1; // Remove this line, as it's causing the problem!
}
delete []vector_1;
Also, you have exactly the same problem in the loop that deals with the vector_2 pointer - and the same 'fix' will work there, too.
Note: If you don't want to use the [i] index operator, but rather use pointer 'arithmetic', then you can change:
new_vector_1[i] = vector_1[i];
to:
new_vector_1[i] = *(vector_1 + i);
This way, you are adding the value of i to the pointer without changing that pointer.