Name Versus Location

Same Name, Different Locations

• Different scope: Block variables
• Same scope, different extent: Recursive variables
• Different scope, different extent: Local variables in two functions

Different Names, Same Location: Aliases

• C++: Pointers

    int number;
    int *pointer;
    pointer = &number;
  

• FORTRAN: Equivalence statements

   INTEGER COUNT, INDEX, NUMBER
   EQUIVALENCE (COUNT, INDEX)
  
   REAL RATE, PERCNT, MAX
   EQUIVALENCE (RATE, PERCNT)
  

• Disadvantages
  • Decreased Readability
  • Decreased Program Verifiability