Tamilnadu Samacheer Kalvi 12th Computer Science Notes Chapter 7 Python Functions Notes
Function:
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:
- User-defined functions
- Built in functions
- Lambda functions
- Recursive functions
1. User defined function:
Functions defined by the users themselves are called User defined functions.
Syntax:
def<function_name ([parameter 1, parameter 2 ]) > :
< Block of statement >
return < expression / None>
Example:
def welcome():
print(“Welcome to Python”)
return
2. Built-in functions:
Functions which are using Python libraries are called Built-in function.
Example:
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 :
- Required arguments
- Keyword arguments,
- 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