Scope
of Variables
All
variables in a program may not be accessible at all locations in that program.
This depends on where you have declared a variable.
The
scope of a variable determines the portion of the program where you can access
a particular identifier. There are two basic scopes of variables in Python −
- Global
variables
- Local
variables
Global
vs. Local variables
Variables
that are defined inside a function body has a local scope, and those defined
outside have a global scope.
This
means that local variables can be accessed only inside the function in which
they are declared, whereas global variables can be accessed throughout the
program body by all functions. When you call a function, the variables declared
inside it are brought into scope. Following is a simple example −
total = 0; #
This is global variable.
#
Function definition is here
def sum( arg1, arg2 ):
#
Add both the parameters and return them."
total = arg1 + arg2; #
Here total is local variable.
print "Inside
the function local total : ", total
return total;
#
Now you can call sum function
sum( 10, 20 );
print "Outside
the function global total: ", total
When
the above code is executed, it produces the following result −
Inside
the function local total: 30
Outside
the function global total : 0
The
return statement
The return statement
is used to exit a function and go back to the place from where it was
called.The statement return [expression] exits a function, optionally passing
back an expression to the caller. A return statement with no arguments is the
same as return None.
Syntax of return
return
[expression_list]
This
statement can contain an expression which gets evaluated and the value is
returned. If there is no expression in the statement or the return statement
itself is not present inside a function, then the function will return
the None object.
For
example:-
All
the above examples are not returning any value. You can return a value from a
function as follows −
#
Function definition is here
def sum( arg1, arg2 ):
#
Add both the parameters and return them."
total = arg1 + arg2
print "Inside
the function : ", total
return total;
#
Now you can call sum function
total = sum( 10, 20 );
print "Outside
the function : ", total
When
the above code is executed, it produces the following result −
Inside
the function: 30
