int() argument must be a string or real number not X [Fixed]

# Table of Contents

1. int() argument must be a string or real number not NoneType
2. int() argument must be a string or real number not, 'list'

# int() argument must be a string or real number not NoneType

The Python "TypeError: int() argument must be a string, a bytes-like object or a real number, not 'NoneType'" occurs when we pass a None value to the int() class.

To solve the error, correct the assignment or provide a fallback value.

Here is an example of how the error occurs.

Copied!
example = None

# ⛔️ TypeError: int() argument must be a string, a bytes-like object or a real number, not 'NoneType'
result = int(example)

We are passing a None value to the int() class which causes the error.

# Common sources of None in Python

The most common sources of None values are:

1. Having a function that doesn't return anything (returns None implicitly).
2. Explicitly setting a variable to None.
3. Assigning a variable to the result of calling a built-in function that doesn't return anything.
4. Having a function that only returns a value if a certain condition is met.

# Providing a fallback value if the variable stores None

One way to solve the error is to provide a fallback value, e.g. 0 if the variable stores None.

Copied!
example = None

result = int(example or 0)

print(result)  # 👉️ 0

If the variable stores None, then 0 gets returned from the expression.

# Functions that don't return anything return None

Functions that don't explicitly return a value return None.

Copied!
# 👇️ this function returns None
def get_str():
    print('100')


# ⛔️ TypeError: int() argument must be a string, a bytes-like object or a real number, not 'NoneType'
result = int(get_str())

You can use a return statement to return a value from a function.

Copied!
def get_str():
    return '100'


result = int(get_str())

print(result)  # 👉️ 100

The function now returns a string that we can convert to an integer.

# Checking if the variable doesn't store None before calling int()

Use an if statement if you need to check whether a variable doesn't store a None value before passing it to the int() class.

Copied!
example = None

if example is not None:
    result = int(example)
    print(result)
else:
    # 👇️ this runs
    print('variable stores a None value')

Alternatively, you can reassign the variable to a fallback value.

Copied!
example = None

if example is None:
    example = 0


result = int(example)

print(result)  # 👉️ 0

# Functions that return a value only if a condition is met

Another common cause of the error is having a function that returns a value only if a condition is met.

Copied!
def get_num(a):
    if a > 15:
        return a


my_num = get_num(10)
print(my_num)  # 👉️ None

The if block in the get_num function is only run if the passed-in number is greater than 15.

To solve the error, you either have to check if the function didn't return None or return a default value if the condition is not met.

Copied!
def get_num(a):
    if a > 15:
        return a

    return 0  # 👈️ return fallback if condition not met


my_num = get_num(10)
print(my_num)  # 👉️ 0

Now the function is guaranteed to return a value regardless if the condition is met.

# int() argument must be a string or real number not, 'list'

The Python "TypeError: int() argument must be a string, a bytes-like object or a real number, not 'list'" occurs when we pass a list to the int() class.

To solve the error, access a specific item in the list and pass the item to the int() class, e.g. int(my_list[0]).

Here is an example of how the error occurs.

Copied!
my_list = ['3', '5', '8']

# ⛔️ TypeError: int() argument must be a string, a bytes-like object or a real number, not 'list'
result = int(my_list)

We passed an entire list to the int() class which caused the error.

# Accessing the list at an index

One way to solve the error is to access the list at a specific index and pass the item to the int() class.

Copied!
my_list = ['3', '5', '8']

result = int(my_list[0])

print(result)  # 👉️ 3

# Joining the items of the list into a string

If you meant to join all the items in the list into a string and convert the result to an integer, use the join() method.

Copied!
my_list = ['3', '5', '8']

my_str = ''.join(my_list)
print(my_str)  # 👉️ '358'

my_int = int(my_str)
print(my_int)  # 👉️ 358

The str.join() method takes an iterable as an argument and returns a string which is the concatenation of the strings in the iterable.

Note that the method raises a TypeError if there are any non-string values in the iterable.

If your list contains numbers or other types, convert all of the values to string before calling join().

Copied!
my_list = ['3', 5, 8]

my_str = ''.join(map(str, my_list))
print(my_str)  # 👉️ '358'

my_int = int(my_str)
print(my_int)  # 👉️ 358

The map() function takes a function and an iterable as arguments and calls the function with each item of the iterable.

# Converting all of the items in the list to integers

You can also use a list comprehension if you need to convert all items in a list to integers.

Copied!
my_list = ['3', '5', '8']

new_list = [int(x) for x in my_list]

print(new_list)  # 👉️ [3, 5, 8]

We pass each string in the list to the int() class to convert each item to an integer.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

• How to Split an Integer into Digits in Python
• Split a Float into Integer and Decimal parts in Python
• Split a String into a List of Integers in Python
• How to print Integer values in Python
• How to take Integer user input in Python
• Join a List of Integers into a String in Python
• Get the length of an Integer or a Float in Python
• TypeError: 'int' object is not callable in Python [Solved]
• Python: Process finished with exit code 137 in PyCharm