Even more Functions CS 1111 SEPTEMBER 23, 2019 Local / Global - PowerPoint PPT Presentation

Even more Functions CS 1111 – SEPTEMBER 23, 2019

Local / Global varibles  Local Variables  Arguments and any variables declared inside a function  Cannot be seen by other functions or code outside the function  If they share a name with a variable outside the function, Python still treats them as though they were a separate variables  Local variables disappear when the function ends  Global variables  Defined outside of the function  Can be referenced in any function AFTER the variable is defined  global keyword required to change a variable in a function.

Local Variables number = 0 def main(): number = int(input( 'Enter a number: ' )) show_number() def show_number(): print( 'The number you entered is ' , number) main()

Local Variables number = 0 def main(): number = int(input( 'Enter a number: ' )) show_number() def show_number(): print( 'The number you entered is ' , number) main() Local variable

Global Variables number = 0 def main(): global number number = int(input( 'Enter a number: ' )) show_number() def show_number(): print( 'The number you entered is ' , number) main()

Calling Functions with Named/Optional parameters  Python only allows on function to exist with a given name  No overloading  However, it does support optional and named arguments  Example: def my_function (name=“Mary”, school=“UVA”): print(name + “ goes to “ + school);  This defines default values for the variables name and school, making them optional

Example: def my_function (name=“Mary”, school=“UVA”): print(name + “ goes to “ + school); #calling function with no arguments my_function() #calling function with one argument (based on order) my_function (“Will”) #calling function with named parameter my_function (school=“WVU”) #calling function with parameter passing (match number of parameters) my_function (“Will”, “WVU”) #calling a function with both named parameters in any order my_function (school=“WVU”, name=“Will”);

Example: def my_function (name=“Mary”, school=“UVA”): print(name + “ goes to “ + school); “Mary goes to UVA” #calling function with no arguments my_function() #calling function with one argument (based on order) my_function (“Will”) #calling function with named parameter my_function (school=“WVU”) #calling function with parameter passing (match number of parameters) my_function (“Will”, “WVU”) #calling a function with both named parameters in any order my_function (school=“WVU”, name=“Will”);

Example: def my_function (name=“Mary”, school=“UVA”): print(name + “ goes to “ + school); #calling function with no arguments my_function() “Will goes to UVA” #calling function with one argument (based on order) my_function (“Will”) #calling function with named parameter my_function (school=“WVU”) #calling function with parameter passing (match number of parameters) my_function (“Will”, “WVU”) #calling a function with both named parameters in any order my_function (school=“WVU”, name=“Will”);

Example: def my_function (name=“Mary”, school=“UVA”): print(name + “ goes to “ + school); #calling function with no arguments my_function() #calling function with one argument (based on order) “Mary goes to WVU” my_function (“Will”) #calling function with named parameter my_function (school=“WVU”) #calling function with parameter passing (match number of parameters) my_function (“Will”, “WVU”) #calling a function with both named parameters in any order my_function (school=“WVU”, name=“Will”);

Example: def my_function (name=“Mary”, school=“UVA”): print(name + “ goes to “ + school); #calling function with no arguments my_function() #calling function with one argument (based on order) my_function (“Will”) #calling function with named parameter my_function (school=“WVU”) “Will goes to WVU” #calling function with parameter passing (match number of parameters) my_function (“Will”, “WVU”) #calling a function with both named parameters in any order my_function (school=“WVU”, name=“Will”);

Example: def my_function (name=“Mary”, school=“UVA”): print(name + “ goes to “ + school); #calling function with no arguments my_function() #calling function with one argument (based on order) my_function (“Will”) #calling function with named parameter my_function (school=“WVU”) #calling function with parameter passing (match number of parameters) “Will goes to WVU” my_function (“Will”, “WVU”) #calling a function with both named parameters in any order my_function (school=“WVU”, name=“Will”);

Importing  You can import your own code from another Python file  Say our my_function () is in a file called “named_parameters.py” import named_parameters # this imports a file called # named_parameters.py # this executes the function called my_function in that file named_parameters.my_function (“Will”, “WVU”)  Format: name_of_file.name_of_function()

In Class Activity  http://www.cs.virginia.edu/~up3f/cs1111/inclass/activity- function.html