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iOS Objective-C Basics (Retired) Functional Programming in C Scope


Can somebody please define scoping in their own words? Thanks!

1 Answer

Aaron Arkie
Aaron Arkie
5,345 Points

Sure, i'll give it a go!

so if we create a method called code() and after the curly braces where there is space where all the code goes you are creating whats called a block. A block defines a scope.

code() { // <---Scope


} //end Scope

Every time you create a new method, class, or statement a block of code is created a scope concurrently will also be created! But beware, variables or objects defined in a block of code or scope that's not in the main scope will not exist outside of its scope.

so let me give you a better example.

class example{ //start of class scope
         public static void main(String[] args) { // main scope

          int A = 7; // this is known to your entire program since its in the main Scope.

          if(A==7) { // a new set of curly braces = a new Scope

                   int B = 2; // this variable is only known to this scope 

                    //A is known here since it was defined in the main scope.
                           Sytem.out.println("A and B are: " + A + " and "  + B)

} //end of IF scope.

                      //we are now in the main Scope again

               B = 5; // B is not known here because it is out of its scope

               // A is still valid because we are now in the main scope.

                Sytem.out.println("A holds the value of: " + A)

}//end of main scope

} //end of class scope

the output will be:

  1. A and B are: 7 and 2; // the if scope
  2. A holds the value of 7;

If we were to have included B inside this print statement:

  Sytem.out.println("A holds the value of: " + A + " and" + B)

We would have reached an error because B does not exist outside its scope.

So just remember this:

Variables are declared once a scope has been created and are only "alive" inside there own scope. If a variable leaves it's scope it is destroyed!

I hope this helps! Goodluck!