Page 113 - trackpad v5.1 class 8 flipbook
P. 113

User-Defined Functions
                 User-defined functions are created by the user according to the need of the program. Once the
                 user defines a function, the user can call it in the same way as the built-in functions.
                 The main difference between these two categories is that built-in functions do not require to
                 be written by us, whereas a user-defined functions are created by the programmer to address
                 specific requirements or perform custom tasks within a program.

                 CREATING A FUNCTION
                 We can create a function in the following ways:

                   Defining a Function: We use the def keyword to begin the function definition.
                   Naming a Function: Provide a meaningful name to your function.

                   Parameters: The parameters (separated by commas) are specified within the parenthesis
                   following the name of the function. These are basically the input values we pass to the function.
                   Body of the Function: The body of the function contains Python statements that make our
                   function perform the required task.
                   The syntax of creating a function is as follows:

                   def < name of the function > (list of parameters)

                             <body>
                 CALLING A FUNCTION

                 A function can be called anytime from other functions or from the command prompt after the
                 definition. For calling a function, we type the function and pass the parameters. For example:
                 To call a function



                                def my_function()                                    Name of a function



                                      print (“Hello”)                                Body of a function



                                my_function()                                         Function call



                 Program 1: To print a string by calling a function
                     Program1.py

                  File  Edit  Format   Run    Options  Window     Help

                  #Function definition
                  def hello (name):
                      print('Hello ' +name+ '! How do you do?')

                  #Calling function by passing parameter
                  hello('Orange')






                                                                                   Functions, String and List in Python  111
   108   109   110   111   112   113   114   115   116   117   118