and no return type does not return value because its return type is void. In this type of function, there are no parameters passed in the function and the function also does not return any value from the function call to the main function.

Code:

#include<bits/stdc++.h>
using namespace std;

// Return type of function is void because value is not returned.
void is_even() {

  int num=4;
  if (num % 2 == 0) {
    cout << num << " is Even number.";
  } else {
    cout << num << " is Odd number.";
  }
}

int main() {
  // No argument is passed to is_even()
  is_even();
 // is_even() does not returns any value.
  return 0;
}

Output: 4 is Even number.

In the above program, the is_even() function is not taking any value as an argument and also it does not return any value.

Functions with no arguments and a return value: - In the program given below, is_even() function is called from the main() with no arguments. is_even() takes a positive integer from the user. Since the return type of the function is a boolean, it either returns true or returns false back to the calling main() function depending upon the input given by the user.

Code:

#include<bits/stdc++.h>
using namespace std;

// Return type of function is bool so it will either return ture of false.
bool is_even() {

  int num=4;

  if (num % 2 == 0) {
    return true;
  } else {
    return false;
  }
}

int main() {
  // No argument is passed to is_even()
  bool ans;
  ans = is_even(); // is_even return the boolean value.
  if (ans) {
    cout << "Num is even number";
  } else {
    cout << "Num is odd number";
  }
  return 0;
}