Scope - Static and Dynamic

Scope - Static and Dynamic

• 1.
  PRINCIPLE OF PROGRAMMING LANGUAGES SCOPE STATIC AND DYNAMIC SNEH PAHILWANI SYMBIOSIS INSTITUTE OF TECHNOLOGY
• 2.
  In computer programming,a scope is the context within a computer program in which a variable name or other identifier is valid and can be used, or within which a declaration has effect. Outside of the scope of a variable name, the variable's value may still be stored, and may even be accessible in some way, but the name does not refer to it; that is, the name is not bound to the variable's storage.
• 3.
  SCOPE STATIC DYNAMIC
• 4.
   Also called lexical scoping.  If a variable name's scope is a certain function, then its scope is the program text of the function definition: within that text, the variable name exists, and is bound to its variable, but outside that text, the variable name does not exist.
• 5.
  Output: 2 3 •Encounter occurrence of „x‟. •Searchlocal block variables •If not there, keep searching in parent blocks. •If not there too, in global scope then. •Otherwise „error‟
• 6.
  SCOPE STATIC DYNAMIC
• 7.
   In dynamic scoping (or dynamic scope), if a variable name's scope is a certain function, then its scope is the time-period during which the function is executing.  While the function is running, the variable name exists, and is bound to its variable, but after the function returns, the variable name does not exist.
• 8.
  Pointing the differenceout •Under static scoping: prints out 2 2 •Under dynamic scoping: prints out 3 4 •At “runtime” one searches for the declaration •Search in local variables •If not found, search in local variables of the caller •If not found, search in global variables •Otherwise error
• 9.
  www.wikipedia.org http://cseweb.ucsd.edu/cl asses/sp05/cse130/lecture_ notes/scoping_student.txt