Scope of Variables and Functions

• Scope of a variable/function refers to the area of the program where the variable/function has a valid existence
• Global Variables/functions:
• Valid everywhere in the program
• It is desirable to minimize the number of global variables
• Declared outside the body of any function
• Created and initialized before the program is started
• Remain in existence until the program terminates
• Local Variables/Functions:
  • Scope limited to the area within the block in which they are declared
  • They are inaccessible outside their block
  • Allocated from the stack. Too many local variables may cause stack overflow
  • Variables are initialized when program control moves into the block
  • Variables are temporary in nature. Also called automatic variables
• Static Variables:
• Static variables are permanent in nature
• They are initialized only once - when the program control first moves into the block
• Their scope is restricted to the block within which they are defined
• Example ...
• If two variables (one global, and the other local) with the same name are defined, the local one takes precedence over the global one, within its scope. Example...