Python Programs - Function Arguments

•             You can call a function by using the following types of formal arguments::

  Required arguments
  
  Keyword arguments
  
  Default arguments
  
  Variable-length arguments

• Required arguments:

  To call the function printme() you definitely need to pass one argument otherwise it would give a syntax error as follows:
  
  #!/usr/bin/python
  
  # Function definition is here
  def printme( str ):
     "This prints a passed string into this function"
     print str;
     return;
  
  # Now you can call printme function
  printme();

• Output

  Traceback (most recent call last):
    File "test.py", line 11, in < module >
     printme();
  TypeError: printme() takes exactly 1 argument (0 given)

• Keyword arguments:

  This allows you to skip arguments or place them out of order because the Python interpreter is able to use the keywords provided to match the values with parameters.
  You can also make keyword calls to the printme() function in the following ways:
  
  #!/usr/bin/python
  
  # Function definition is here
  def printme( str ):
     "This prints a passed string into this function"
    print str;
    return;
  
  # Now you can call printme function
  printme( str = "My string");

• Output

  My string

• Default arguments:

  #!/usr/bin/python
  
  # Function definition is here
  def printinfo( name, age = 35 ):
   "This prints a passed info into this function"
   print "Name: ", name;
   print "Age ", age;
   return;
  
  # Now you can call printinfo function
  printinfo( age=50, name="miki" );
  printinfo( name="miki" );

• Output

  Name: miki
  Age 50
  Name: miki
  Age 35

• Variable-length arguments:

  Syntax:

  def functionname([formal_args,] *var_args_tuple ):
   "function_docstring"
   function_suite
   return [expression]
  
  Example:
  #!/usr/bin/python
  
  # Function definition is here
  def printinfo( arg1, *vartuple ):
    "This prints a variable passed arguments"
    print "Output is: "
    print arg1
    for var in vartuple:
      print var
  return;
  
  # Now you can call printinfo function
  printinfo( 10 );
  printinfo( 70, 60, 50 );

• Output

  Output is:
  10
  Output is:
  70
  60
  50