Modifiers in C++

[sukishan]

Modifiers

In a declaration, modifiers before the type name apply to all objects in the list. Otherwise they apply to single objects.

  int* p, q;           // p is a pointer, q is an int
  const int a=0, b=0;  // a and b are both const

const

const objects cannot be modified once created. They must be initialized in the declaration. By convention, const objects are UPPERCASE when used globally or as parameters.

  const double PI=3.14159265359;  // Assignment to PI not allowed

References
A reference creates an alias for an object that already exists. It must be initialized. A reference to a const object must also be const.
  int i=3;
  int& r=i;         // r is an alias for i
  r=4;              // i=4;
  double& pi=PI;    // Error, would allow PI to be modified
  const double& pi=PI;  // OK