Python Program to Check Even or Odd Number

Given a number and our task is to check number is Even or Odd using Python and If the number is even or odd then return true or false.

Example:

Input: 2
Output: Even number

Input: 41
Output: Odd Number

Using Modulus operator check if number is even or odd

For that, we use the Operator Called Modulus Operator. This operator used in the operation when we need to calculate the remainder of that number when divided by any divisor.

Python3

x = 2
# x= 41

if x % 2 == 0:
    print(x,"Is Even Number")
else:
    print(x, "Is Odd Number")

Output:

2 Is Even Number

Time Complexity : O(1)
Auxiliary Space : O(1)

Using Ternary operator check if number is even or odd

Here we will use the ternary operator to check the number is divisible by 2 or not.

Python3

num = 5
print(num , "is Even") if num%2 == 0 else print(num, "is Odd")

Output:

5 is Odd

Using recursion check if number is even or odd

Example 1:

We use the concept of getting the remainder without using the modulus operator by subtracting the number by number-2. If at last, we get any remainder then that number is odd and return the False for that number. Else the number is even and return True for that number

Python3

# defining the function having the one parameter as input
def evenOdd(n):

    #if remainder is 0 then num is even
    if(n==0):
        return True

    #if remainder is 1 then num is odd
    elif(n==1):
        return False
    else:
        return evenOdd(n-2)

# Input by geeks
num=3
if(evenOdd(num)):
    print(num,"num is even")
else:
    print(num,"num is odd")

Output

3 num is odd

Time Complexity : O(1)
Auxiliary Space : O(1)

Example 2:

We use the modulus operator to find the even or odd Like if num % 2 == 0 then the remainder is 0 so the given number is even and returns True, Else if num % 2 != 0 then the remainder is not zero so the given number is odd and return False

Python3

# defining the function having
# the one parameter as input
def evenOdd(n):

    #if remainder is 0 then num is even
    if(n % 2 == 0):
        return True

    #if remainder is 1 then num is odd
    elif(n %2 != 0):
        return False
    else:
        return evenOdd(n)

# Input by geeks
num = 3
if(evenOdd( num )):
    print(num ,"num is even")
else:
    print(num ,"num is odd")

Output

3 num is odd

Time Complexity : O(1)
Auxiliary Space : O(1)

Using the AND (&) Operator To Check whether Number is Even or Odd

For this method, we just need to use the & operator, which is a bitwise operator, and it works the same way as the % operator for this particular case. 

If given number & 1 gives 1, the number would be odd, and even otherwise.

Python3

# defining the function having
# the one parameter as input

def evenOdd(n):

  # if n&1 == 0, then num is even
  if n & 1:
    return False
  # if n&1 == 1, then num is odd
  else:
    return True


# Input by geeks
num = 3
if(evenOdd(num)):
    print(num, "num is even")
else:
    print(num, "num is odd")

Output:

3 num is odd

Time Complexity : O(1)
Auxiliary Space : O(1)

Print all the even numbers for the range (a, b) using Recursion

Here We will print all the even numbers for the Given Range n in the Function evenOdd(n)

Python3

# writing the function having the range
# and printing the even in that range
def evenOdd(a,b):
    if(a>b):
        return
    print(a ,end=" ")
    return evenOdd(a+2,b)

# input by geeks
x=2
y=10
if(x % 2 ==0):
    x=x

else:

    # if the number x is odd then
    # add 1 the number into it to
    # avoid any error to make it even
    x+=1
evenOdd(x,y)

Output:

2 4 6 8 10 

Time Complexity : O(1)
Auxiliary Space : O(1)

Print all even or odd numbers in a given range (a,b) without using Recursion

In this approach, we will see how we can find even numbers in a given range and print them without Recursion.

• First we will define a function that takes an integer input and checks if the number is even or odd. It returns 1 if the number is even, otherwise 0.
• We will define a starting value and an ending value, this will be our range in which we will find all the even numbers.
• We will run a loop from the starting value till the ending value (both inclusive) and check using our function that if that number is even or odd.
• We will print the value if the number is found even , otherwise, we will pass and go to the next number.

Python3

# Python program to find even
# or odd in a given range
# without using Recursion

# defining the function
# to check if the number
# is even or odd
def even_or_odd(num : int) -> int:
  if num % 2 == 0:
    return 1
  return 0


# Starting point of the range
start = 2

# ending point of the range
end = 10

# Iterating over each
# element in the range and checking
# if it is even or odd
# using our function and printing
for i in range(start,end+1):
  if even_or_odd(i):
    print(i,end= " ")
  else:
    pass

Output:

2 4 6 8 10 

Time Complexity – O(n) # n = the range in which we are searching.

Space Complexity – O(1) # Only two extra variables are being used.