Есть ли введенное число в массиве?

#include <iostream>
using namespace std;
 
int main()
{
    unsigned N;
    cout << "Size of array: ";
    cin >> N;
    int * arr = new int[N];
    cout << "Fill array:\n";
    for (unsigned i = 0; i < N; ++i)
    {
        cout << "el #" << i + 1 << ": ";
        cin >> arr[i];
    }
    bool flag = false;
    cout << "Enter value of element you want to find: ";
    int to_find;
    cin >> to_find;
    for (unsigned i = 0; i < N; ++i)
        arr[i] == to_find ? flag = true : 0;
    if (flag)
        cout << "Element found!\n";
    else
        cout << "Element not found!\n";
    system("pause");
}

#include <vcl.h>
#include <stdio.h>
#include <conio.h>
#pragma hdrstop
#pragma argsused
 
void main()
{
int i,n;
int a[10];
printf("\n Enter massiv : ");
for( i=0; i<10; i++)
  scanf("%d",&a[i]);
 
printf("\n Vvedite chislo dlya proverki : ");
scanf("%d", &n);
 
int flag=0;
for (i=0; i<10; i++)
 if (a[i]==n) flag++;
 
if (flag>0) printf("\n Chislo est v massive");
   else      printf("\n Chisla net v massive");
 
getch();
}

#include <iostream>
#include<cstdlib>
 
int main()
{
    size_t arraySize;
    std::cout<<"Input the size of the array: ";
    std::cin>>arraySize;
    int *array = new int [arraySize];
    std::cout<<"Input the array elements: ";
    for(size_t i=0;i<arraySize;i++)
        std::cin>>array[i];
    int number;
    std::cout<<"\nInput the number: ";
    std::cin>>number;
    bool flag(false);
    for(size_t i=0;i<arraySize;i++)
        flag = number == array[i]?true:flag;
    std::cout<<std::boolalpha<<flag;
 
}

#include <iostream>
 
int main()
{
   int n;
   std::cout << "n: ";
   std::cin >> n;
 
   int* a = new int[n];
   for(int i = 0; i < n; ++i)
      std::cin >> a[i];
 
   int k;
   std::cout << "search: ";
   std::cin >> k;
 
   int j = 0;
   while(j < n && a[j] != k) ++j;
   std::cout << (j < n ? "found" : "not found") << std::endl;
   
   delete[] a;
}

#include <iostream>
#include <algorithm>
#include <vector>
 
int main()
{
  std::vector<int> array;
  int tmpVar = 0;
  int findVar = 0;
  std::cout << "Input find var = "; std::cin >> findVar;
  std::cout << "Input array : " << std::endl;
  
  while(std::cin >> tmpVar)
    array.push_back(tmpVar);
  
  std::vector<int>::const_iterator it = std::find(array.begin(), array.end(), findVar);
  if(*it)
    std::cout << findVar << " is found at " << *it << " position " << std::endl;
  else
     std::cout << findVar << " is not found " << std::endl;
  
  system("PAUSE");
  return 0;
}

if(it != array.end())