Variable declarations can be put inside the code without using hooks

NOTE : -

THIS CONTENT IS NOT ORIGINAL

4. Variable declarations can be put inside the code without using hooks

Variables can be declared anywhere inside the code:

using namespace std;
#include 

int main ()
{
  double a;

  cout << "Hello, this is a test program." << endl;

  cout << "Type parameter a: ";
  cin >> a;
                                                                                                
   a = (a + 1) / 2;

  double c;

  c = a * 5 + 1;

  cout << "c contains      : " << c << endl;

  int i, j;

  i = 0;
  j = i + 1;

  cout << "j contains      : " << j << endl;

  return 0;
}

Output

Hello, this is a test program. Type parameter a: 7 c contains : 21 j contains : 1

Maybe try to use this feature to make your source code more readable and not to mess it up.
Like in C, variables can be encapsulated between { } blocks. Then they are local in scope to the zone encapsulated between the { and }. Whatever happens with such variables inside the encapsulated zone will have no effect outside the zone:

using namespace std;
#include 

int main ()
{
  double a;

  cout << "Type a number: ";
  cin >> a;

  {
     int a = 1;
     a = a * 10 + 4;
     cout << "Local number: " << a << endl;
  }

  cout << "You typed: " << a << endl;

  return 0;
}

Output

Type a number: 9 Local number: 14 You typed: 9

BIBILOGRAPHY / REFERENCE : - http://www.4p8.com/eric.brasseur/cppcen.html