Convert a number into binary format in C,C++

There are multiple approaches to do the same. I am listing three methods known to me.
Here is the code :

#include <iostream>
#include <conio.h>
#include <bitset>
#include <iomanip>

using namespace std;

void Method_1(int num)
{
  const std::string result = bitset<sizeof(num)*CHAR_BIT>(num).to_string();
  cout << result.substr(result.find("1", 0));
}

void Method_2(int num)
{
  if (num / 2 != 0)
  {
    Method_2(num / 2);
  }

  cout<<num % 2;
}

void Method_3(int num)
{
  std::string result = "";

  for (int i = (sizeof(num)* CHAR_BIT); i >= 0; --i)
    result += ((num & (1 << i)) ? "1" : "0");

  cout << result.substr(result.find("1", 0));
}

void main()
{
  int num = 30;

  cout << "Method 1 : "; Method_1(num);  cout << endl;
  cout << "Method 2 : "; Method_2(num);  cout << endl;
  cout << "Method 3 : "; Method_3(num);  cout << endl;
  
  _getch();
}

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