FunctionParameter.md

Function Arguments

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. Arbitrary 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 iterable preceded by *.

• In positional arguments, we need to maintain sequence as we calling area. Syntax:

#Positional Arguments
Functionname(element1,element2)

#Using Tuple Data
Functionname(*(element1,element2))

Example

def Addition(a,b):
       return a+b
res=Addition(5,6)
print(res)

Output:

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 an element with one keyword.

How to define keyword arguments

Syntax:

#Function To Accepts keywords arguments
def functionname(key1,key2):
     #function code block

#Keywords Arguments
Functionname(key1=value,key2=value2)

#Using Dictionary
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

Output:

12
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 Addition(a,b=7):
      #here default of b is set to 7 if b is not passed
      return a+b

res=Addition(5) 
# here we have pass only a value
print(res)

#Result:12

Output:

12

Example 2:

def Addition(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) 
# here we have pass only a,b value
print(res)

#Result:14

Output:

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 allows us to pass the variable number of no 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 the 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

Output:

11
18
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 a function with name the same as the parameter excluding double asterisk **.

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.items():
           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

Output:

11
18