how to make functions in python | max(),min(),factorial(),pallindrome()

 How to Make functions in python

As we know in python math module there is in built functions are factorial(),max(),min(),pallindrome() .thesefunctions are in built ,buthere today we will learn how to define these function by user (you or I).

so we are going to make function i.e

max().

Testcases1:

Input:

[1,6,3,7,7]

Output:

7

Testcases2:

[9,7,90,43]

Output:

90

#First to make your function you have to use def keyword to define your function.and then write your function name,herewe will name the function i.emax()

        def max():

            

        # then input() function to take input and use eval() to input numbers in the eval form it means evalution

            lst=eval(input("Enter a numbers in the list:"))

            max=lst[0]

            

        #Now you have input the list ,nowits time to access the every element to check which  number is maximum in the list take for loop

            for i in range(len(lst)):

        #Then test every element of the list using index value if any index value is greater than the assumming value of the list then that index value assign to max variable 

                if lst[i]>max:

                    max=lst[i]

            #in else part use pass key word

                else:

                    pass

            #Use print() function to print max value in the input list

            print(max)

#Now your 100% program is ready now if you want execute this program you have to call your program         max()

#Now your max()function is made by your code ,so i think you have understood that you can also make the functions that are already made i.ein built function.

So my aim is to clarify you that all the functions are made using these things these are not automatically made or these are not made by any .

Now we will move forward to make min() function to find number from the list

Testcases1:

Input:

[9,6,96,9,1,8,7]

Output:

1

Testcases2:

Input:

[1,-7,4,8,3]

Output:

-7

#First similarily use def keyword to define your function named as min()function 

            def min():

            #now in the indent input list using input()

                lst=eval(input())

            #Take minimum value i.e 0 index value  of the list

                min=lst[0]

            #now use for loop to iterate 

                for i in range(len(lst)):

            #Then test the condition if the calue of any index value is less than the 0 index value of the list then assign that index value to min variable

                    if lst[i]<min:

                        min=lst[i]

                    else:

                        pass

                #now use print()function to print minimum value of the list

                print(min)

            #If you want to execute above ,so you have to call your function i.e min()function

            min()

Through this program or by calling your function you can find minimum value from the list.

Now i think you have learned that how can you make your own function even you can call your own function in another file .

Now we will make function i.e factorial function that is already inbuilt in python module i.e math module but here we will learn how to make our factorial function .

Factorial means 

5! (This is called five factorial)=5*4*3*2*1=120

4=4*3*2*1=24

Testcases1:

5

Output:

120

#Let first define your function using def keyword

def factorial():

#Now write main program of factorial in the indent of the function.

#Input number using input() function

    num=int(input("Enter any positive number:"))

#assume fact=1

    fact=1

#take a for loop to iterate and find factorial of the input number that start from 1 to upto num 

    for i in range(1,num+1):

        fact=fact*i

    #use print()function to print factorial of a given number

    print(fact)

#Now its time to execute your program to execute you have to call your function

factorial()

How this program will run see below:

Let take example 

num=5

Now it will go to for loop the value of i will go upto num because for loop go upto num+1-1 i.e num

so ,

fact=fact*i

here value of   

i=1                     fact=1

fact=1*1=1

now value of i will increase by +1

i=2  fact=1

fact=1*2=2

i=3    fact=2

fact=2*3=6

i=4  fact=6

fact=6*4=24

i=5  fact=24

fact=24*5=120

this is program how it will run.

Similarily we will move to make a function i.e pallindrome() function to pallindrome of any number.

Pallindrome means it opposite is equal then it is called pallindrome.

Example;

N=121

This is pallindrome

N=122

Not pallindrome number.

Testcases1:

Input:

121

Output:

Pallindrome number

Testcases2:

Input:

231

Output:

Not Pallindrome

How To check pallindrome number?

To check given number is pallindrome or not ,you must have to reverse the given number.then we can check that the given number is pallindrome or not.

#Let us start we will make pallindrome() function using def keyword.To check number is pallibdrome then we must have to reverse the input number then we can check gicen number is pallibdrome or not.

def pallindrome():

#Now we will input the  any number using input()function

    N=int(input("Enter any number:"))

#Take reverse is 0 as rev

    rev=0

    temp=N

#Now take while loop until the number is greater than 0

    while(N>0):

        rem=N%10

#here rem is to get remainder of the input number because modolus operator return decimal number

        rev=rev*10+rem

    #Now we will take number before decimal using floor division operator

        N=N//10

    #Now check the number if the input number is equal to reverse number then it is pallindrome

    if temp==rev:

        print('Given number is pallindrome.')

    else:

        print("Not pallindrome.")

#Now to execute your program you have to call your pallindrome function

pallindrome()

How This program will execute:

Let take a example:

N=121

Now value of rev=0   i.e reverse and temp=121 beacuse we have assigned the value of N in temp variable

Now while loop check your given number greater than 0 or not.Here True then it will execute the task in its indent

Now 

rem=N%10=121%10=1

rev=rev*10+rem=0*10+1=1

N=N//10=121//10=12

Again now value of N will check in the while loop it is greater than 0 the again it will come in its intend and do the task.

rem=N%10=12%10=2    because N=12

rev=rev*10+rem=1*10+2=12

N=N//10=12//10=1

Now value of N is 1 that is greater than 0 or not .

Now it will come in the intend

rem=1%10=1

rev=rev*10+rem=12*10+1=121

N=N//10=1//10=0

Now value of N is 0 then N is not greater than 0 so your loop will stop.