Steps followed:
1. take range as input from user
2. validate user input by converting to integer
3. check if given range is valid
4. print even number falling in given range

Program

#python program to print even number in given range

#take range as input from user

lower_range,upper_range = input("Enter range in format lower range,upper range: ").split(",")

try:

    lower_range=int(lower_range)

    upper_range=int(upper_range)

    # check if given range is valid

    if upper_range <= lower_range:

        print("invalid range")

    else:

        for i in range(lower_range,upper_range+1):

            if i % 2 == 0:

                print(i, end=" ")

            else:

                continue       

except:

    print("---error---")

    print("please enter a valid input")

Output

Enter range in format lower range,upper range: 10,50

10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

 

Enter range in format lower range,upper range: 25,14

invalid range

 

Enter range in format lower range,upper range: x,y

---error---

please enter a valid length

► Python program to print even number in given range