Tamilnadu Samacheer Kalvi 12th Computer Science Notes Chapter 7 Python Functions Notes

A named blocks of code that are designed to do one specific job is called
as Function.

Block in python:
A block is one or more lines of code, grouped together so that they are treated as one big sequence of statements while execution.

Main advantages of function:

  • It avoids repetition and makes a high degree of code reusing.
  • It provides better modularity for your application.

Recursive Function:
A Function which calls itself is called as Recursive Function.

Different types of function:

  1. User-defined functions
  2. Built in functions
  3. Lambda functions
  4. Recursive functions

1. User defined function:
Functions defined by the users themselves are called User defined functions.

def<function_name ([parameter 1, parameter 2 ]) > :
< Block of statement >
return < expression / None>

def welcome():
print(“Welcome to Python”)

2. Built-in functions:
Functions which are using Python libraries are called Built-in function.

print ()

3. Lambda function:

  • Lambda function is mostly used for creating small and one-time anonymous function.
  • Lambda functions are mainly used in combination with the functions like filterQ, map() and reduceQ.

Syntax of Lambda function (Anonymous Functions):
lambda [argument(s)]: expression

4. Recursive function:

  • A recursive function calls itself. Imagine a process would iterate indefinitely if not stopped by some condition! Such a process is known as infinite iteration.
  • The condition that is applied in any recursive function is known as a base condition.
  • A base condition is must in every recursive function otherwise it will continue to execute like an infinite loop.

Scope of variable:

  • Scope of variable refers to the part of the program, where it is accessible,
  • The scope holds the current set of variables and their values.
  • The two types of scopes are – local scope and global scope.

Local Scope:
A variable declared inside the function’s body or in the local scope is known as local variable.

Global scope:

  • A variable, with global scope can be used anywhere in the program.
  • It can be created by defining a variable outside the scope of any function or block.

Parameters and arguments:

  • Parameters are the variables used in the function definition.
  • Arguments are the values we pass to the function parameters.

Arguments Types:

  • Arguments are used to call a function.
  • There are primarily four types of functions namely :
    1. Required arguments
    2. Keyword arguments,
    3. Default arguments S Variable-length arguments

Required Arguments:

  • “Required Arguments” are the arguments passed to a function in correct positional order.
  • The number of arguments in the function call should match exactly with the function definition.
  • Atleast one parameter to prevent syntax errors to get the required output.

Keyword Arguments:

  • Keyword arguments will invoke the function after the parameters are recognized by their parameter names.
  • The value of the keyword argument is matched with the parameter name and so, one can also put arguments in improper order (not in order).

Default Arguments:
In Python the default argument is an argument that takes a default value if no value is provided in the function call.

Variable-Length Arguments:

  • In some instances it is needed to pass more arguments that have already been specified.
  • These arguments are not specified in the function’s definition and an asterisk (*) is used to define such arguments.
  • These types of arguments are called Variable-Length arguments.

Composition in functions:

  • The value returned by a function may be used as an argument for another function in a nested manner is called

Samacheer Kalvi 12th Computer Science Notes