'\0' null character 0
'\n' newline 10
'\r' return 13
'\t' tab 9
' '  space 32
'0'  zero digit 48
'A'  upper case A 65
'a'  lower case a 97

float square(float x)
{
  return x * x;
}

 #include <iostream.h>
int main()
{
  cout << square(2.0);
  return 0;
}

class Circle
{
private: // the Implementation
  int radius;
  int centerX;
  int centerY;
  const float PI = 3.14159;
public: // the Interface
  Circle(int newX, int newY, int newRadius)
  {
    centerX = newX;
    centerY = newY;
    radius = newRadius;
  }
  float area()
  {
    return PI * radius * radius;
  }
};

 #include <iostream.h>
int main()
{
  Circle c(0,0,1);
  cout << "The area of Circle c is " << c.area() << endl;
  return 0;
}

{
  Circle c(0,0,1); // c is born
  ... // c is alive - we can ask it's area
} // c dies - no more Circle c

{
  float i = 0.0;
  // float i is  in scope
  {
    int i = 0; // outer float i is  hidden by local integer i
    // int i is  in scope
  }
  // float i is back  in scope
  // int i is  out of scope
}
// both the objects named i are  out of scope