Formal and actual parameters

Formal and actual parameters

def  f1(a,b):

 …..

 …..

#Function call

f1(10,20)

Here a,b are formal parameters, where as 10,20 are actual parameters (arguments)

There are 4 types of actual parameters are allowed in Python

1.     Positional arguments

2.     Keyword arguments

3.     Default arguments

4.     Variable length arguments

Positional Arguments:

#example program on positional arguments

def add(a,b):

    c=a+b

    print(c)

add(10,6) #positional arguments

add(2,3)

"""output:

16

5

>>>

"""

The number of arguments and position of arguments must be matched. If we change the order then result may be changed. If we change the no of arguments then we will bet error.

Parameters passed to a function in correct positional order.

2.  keyword arguments

#keyword arguments example

def college(name,marks):

    print('name=',name)

    print('marks=',marks)

#call student marks and pass arguments

college(name='sita',marks=75)

college(name='ravi',marks='60')

"""output:

name= sita

marks= 75

name= ravi

marks= 60
Note:

1: college('ravi', '60')# Valid

2: college(marks='80',name='rama')#Valid

3: college(marks='80', 'rama') #Error Positional arguments follows keyword

4: college(80,'rama') # Valid

5: college(n='sita',m=75)# Error

>>> """

We can pass arguments values by keyword i.e by parameter name

Here we are mentioning the keyword ‘name’ and another keyword ‘marks’. At the time of calling the function, we have to pass two values and we can mention which value is for what.

These keywords are nothing but parameter names which receive these values.

We can change the order of the arguments:

Ex: college(marks='80',name='rama')

3. Default Arguments:

#default arguments

def ex(a,pi=3.14159):

    print(a,pi)

ex(5)

ex(6,3.15)

"""output:

5 3.14159

6 3.15

>>> """

Sometimes we can provide default values for our positional arguments. If we are not passing any argument (actual parameter) from the function call then only default value will be considered.

5.     Variable length arguments

"""

Related Video: https://www.youtube.com/playlist?list=PL2mD2CO8TKlJdFbbtuhTXPQk2tNQx0pb1

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