Scope of Variables

Scope Scope of a variable is the range of statements in which the variable is visible in a program A variable is visible in a statement if the variable name could be used in the location the statement occupies Scope rules determine how variable references throughout a program are resolved

Static Scope COBOL introduced typed variables with global scope ALGOL 60 popularized the use of static scoping using begin and end to create blocks of code that could be nested

ALGOL 60 Program begin integer x, y; x = 3; printint(x); if (x < 5) end; end

Dynamic Scoping Dynamic scoping uses a program call sequence to determine the scope of a variable {int x = 0; Define int foo () { return x; } Define int goo () { int x = 1; return foo(); } goo();} Calling goo() with static scoping returns 0 Calling goo() with dynamic scoping returns 1 since a stack is used to maintain the bindings of each variable as a program block is entered