Programming Languages Basic

Programming Languages Basic

1. Static / Dynamic

   • Static
     • Allows the compiler to decide at compile time
   • Dynamic
     • Decisions made at run time

2. Scope of declarations

   • Whole are in which that variable can be accessed by name

3. Scoping

   • Search for a variable with a given time

4. Environment & States

   • Environment
     • Mapping from names to location
   • States
     • Mapping from location to value

5. Block

   • Grouping of declarations and stamentes {}

6. Dynamic Scope

   • What can be known ONLY when the program executes
   • Macro Expansion
     • C
   • Methon resolution
     • Object oriented programming
   • Definition
     • Value of the things
   • Declarations
     • Type of things
   • Polymorphic procedures
     • Have 2 or more definitions for the same name

7. Parameters passing mechanism

   • Call by value
     • void swap(int x, int y)
     • The actual parameter is evaluated or copied
     • The actual parameters cannot be changed
   • Call by reference
     • void swap(int * x, int *y)
     • The address of the actual parameters is passed to the calle
     • Changes to the formal param -> changes to the actual param
   • Call by name
     • substituted literally for the formal parameter

8. Aliasing

   • two formal parameters can refer to the same locations.
   • Passing the same array as x and y will modify boths