Program to compute sum of even and odd numbers received in stream by user-CodePudding

In this particular code I have to find the sum of even and odd number given the by user in stream, as I can observe everything is ok in the code but still not able to run it and getting ValueError: invalid literal for int() with base 10:

sum_of_even_number=0
sum_of_odd_number=0

while True:  # We have created a infinite loop
    user_input=input()
    if user_input=="\n\n":
        break
    num=int(user_input)
    if num % 2==0:
        sum_of_even_number =num
    else:
        sum_of_odd_number =num

print("sum_of_even_number :  ",sum_of_even_number)
print("sum_of_odd_number :  ",sum_of_odd_number)

CodePudding user response：

You're getting a Value Error because you are trying to parse an empty string. If the user presses the enter key, then it gets formatted as a string with no text. So instead of checking to see if your text contains \n, check to see if its an empty string or not, like this:

sum_of_even_number=0
sum_of_odd_number=0

while True:  # We have created a infinite loop
    user_input=input()
    if user_input == "":
        break
    num = int(user_input)
    if num % 2 == 0:
        sum_of_even_number  = num
    else:
        sum_of_odd_number =num
        
print("sum_of_even_number :  ",sum_of_even_number)
print("sum_of_odd_number :  ",sum_of_odd_number)

For more help: ValueError: invalid literal for int() with base 10: ''

CodePudding user response：

Your while loop can be controlled by user input. In this example, if user input is empty then the loop will break. Try this:

evens_and_odds = [0, 0]

while user_input := input('Please enter a number: '):
    try:
        x = int(user_input)
        evens_and_odds[x%2]  = x
    except ValueError as e:
        print(e)

for i, e in enumerate(('even', 'odd')):
    print(f'Sum of {e}s = {evens_and_odds[i]}')

Note:

Always test user input when you expect numbers.

You will need Python 3.8 for this

CodePudding user response：

See comments in line.

sum_of_even_number = 0
sum_of_odd_number = 0

while True:  # We have created a infinite loop
    user_input = input()
    # Change if user_input=="\n\n": to if user_input == "":
    # input() does not return  \n
    # If no entry is made input() returns an empty string
    if user_input == "":
        break
    # The original code passed empty string.
    # The following produced the value error because the empty string can not
    # be converted to integer.
    num = int(user_input)
    if num % 2 == 0:
        sum_of_even_number  = num
    else:
        sum_of_odd_number  = num

CodePudding user response：

Edit: Fixing indentation.

Without Walrus operator:

Before: Using same code as your. I put print inside if/else condition block Use the f-string format as well.

sum_of_even_number=0
sum_of_odd_number=0

while True:  # We have created a infinite loop
    user_input=input('Enter number:')
    if user_input=="\n\n":
        break
    num=int(user_input)
    if num % 2==0:
        sum_of_even_number =num
        print(f"sum_of_even_number : {sum_of_even_number}")
    else:
        sum_of_odd_number =num
        print(f"sum_of_odd_number :  {sum_of_odd_number}")

With Python 3.8 Walrus Operator:

sum_of_even_number=0
sum_of_odd_number=0

while (user_input := input('Enter number:')):  # We have created a infinite loop
     
    num = int(user_input)
    if num % 2 == 0:
        sum_of_even_number = num
        print(f"sum_of_even_number : {sum_of_even_number}")
    else:
        sum_of_odd_number = num
        print(f"sum_of_odd_number :  {sum_of_odd_number}")

Both output are same.

Enter number:6
sum_of_even_number : 6
Enter number:5
sum_of_odd_number :  5
Enter number:8
sum_of_even_number : 8
Enter number:100
sum_of_even_number : 100
Enter number:105
sum_of_odd_number :  105
Enter number: