Day 14:Lecture 1

Content: Function Passing arguments

Author:Ravishankar Chavare

Date:13-06-2019

LinkedIn:https://www.linkedin.com/in/ravishankar-chavare-84474a102

*Function arguments*

*What is mean by argument's*

A value passed to a function (or method) when calling the function called as arguments.

Python support following types of arguments for function

1.positional arguments

2.Default arguments

3.Keyword arguments

4.Arbitary arguments

*1.Positional arguments*

- An argument that is not a keyword argument. Positional arguments can appear at the beginning of an argument list and/or be passed as elements of an iterablepreceded by *.

- In positional arguments we need to maintain sequence as we calling area.

Syntax:

Functionname(element1,element2)

Or

Functionname(*(element1,element2))

Example

def Addition(a,b):

return a+b

res=Addition(5,6)

print(res)

#Result:11

*2.Keyword arguments*

- An argument preceded by an identifier (e.g. name=) in a function call or passed as a value in a dictionary preceded by **

- Here we don't need to maintain position because we are defining element with one keyword.

How to define keyword arguments

Syntax:

Functionname(key1=value,key2=value2)

Or

functionname(**{'key1':value1,'key2':value2})

How to access elements in function

Syntax:

def functionname(key1,key2):

#function code block

Example:

def Addition(b,a):

return a+b

#keyword using

res=Addition(a=5,b=7)

#Using keywords with dictionary

result= Addition(**{'a'=5,'b'=7})

print(res)

#Result:12

print(result)

#Result:12

*3.Defualt parameter*

- Python allows function arguments to have default values. 

- If the function is called without the argument, the argument gets its default value.

The default value is assigned by using assignment(=) operator of the

Syntax:

keywordname=value.

Example 1:

def Adition(a,b=7):

#here default of b is set to 7 if b is not passed

return a+b

res=Addition(5)

print(res)

#Result:12

Example 2:

def Adition(a,b=7):

#here default value 7 is not set because we have passed a,b from calling function

return a+b

res=Addition(5,9)

print(res)

#Result:14

*4.Arbitary arguments*

- In Python, we can pass a variable(dynamic length) number of arguments to a function using special symbols.

There are two special symbols:

1. *args(Non Keyword Arguments)

2. **kwargs (Keyword Arguments)

*1. *args*

- Python has *args which allow us to pass the variable number of non keyword arguments to function.

- Use an asterisk * before the parameter name to pass variable length arguments.

-The arguments are passed as a tuple and these passed arguments make tuple inside the function with same name as the parameter excluding asterisk *

Syntax:

When calling function

functionname(V1,V2,V3.....)

Inside Function

def functioname(*varname):

for i in varname:

#do your computation on i variable

Example:

def Addition(*numb):

add=0

for i in numb:

add=add+i

return add

#send 2 arguments

res=Addition(5,6)

print(res)

#Result:11

#send 3 arguments

res=Addition(5,6,7)

print(res)

#Result:18

#send 4 arguments

res=Addition(5,6,7,1)

print(res)

#Result:19

2.**kwargs

- **kwargs, it allows us to pass the variable length of keyword arguments to the function.

- The arguments are passed as a dictionary and these arguments make a dictionary inside function with name same as the parameter excluding double asterisk **.

Syntax:

Syntax:

When calling function

functionname(k1=V1,k2=V2,k3=V3.....)

Inside Function

def functioname(**varname):

for key,value in varname.items():

# do operation on key and value

Example:

def Addition(**numb):

add=0

for key,value in numb:

add=add+value

return add

#send 2 arguments

res=Addition(a=5,b=6)

print(res)

#Result:11

#send 3 arguments

res=Addition(a=5,b=6,c=7)

print(res)

#Result:18