Check if a string can be converted to an Integer in Python

Check if a string can be converted to an Integer in Python #

To check if a string can be converted to an integer:

1. Wrap the call to the int() class in a try/except block.
2. If the conversion succeeds, the try block will fully run.
3. If the conversion to integer fails, handle the ValueError in the except block.

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def can_convert_to_int(string):
    try:
        int(string)

        return True
    except ValueError:
        return False


print(can_convert_to_int('1357'))  # 👉️ True
print(can_convert_to_int('-1357'))  # 👉️ True
print(can_convert_to_int('1.357'))  # 👉️ False
print(can_convert_to_int('ABC123'))  # 👉️ False

We used a try/except block to check if a string can be converted to an integer.

If calling the int() class with the string fails, a ValueError is raised and the function returns False.

We pass the string to the int() class not knowing whether the conversion will be successful, and if a ValueError error is raised, we handle it in the except block.

Alternatively, you can use the str.isdigit() method.

Check if string can be converted to Integer using isdigit() #

Use the str.isdigit() method to check if a string can be converted to an integer, e.g. if my_str.isdigit():. If the str.isdigit method returns True, then all of the characters in the string are digits and it can be converted to an integer.

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my_str = '1357'

if my_str.isdigit():
    my_int = int(my_str)
    print(my_int)  # 👉️ 1357

    print('✅ string can be converted to integer')
else:
    print('⛔️ string CANNOT be converted to integer')

We used the str.isdigit() method to check if a string can safely be converted to an integer.

The str.isdigit method returns True if all characters in the string are digits and there is at least 1 character, otherwise False is returned.

The method checks if all characters in the string are digits, so if the string had a minus sign or a decimal, it would return False.

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my_str = '-1357'

if my_str.isdigit():
    my_int = int(my_str)
    print(my_int)

    print('✅ string can be converted to integer')
else:
    # 👇️ this runs

    print('⛔️ string CANNOT be converted to integer')

If you just want to try converting the string to an integer and silence/ignore the ValueError if the conversion fails, use a pass statement.

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my_str = '2468'

try:
    my_int = int(my_str)
    print(my_int)  # 👉️ 2468
except ValueError:
    pass

The pass statement does nothing and is used when a statement is required syntactically but the program requires no action.

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class Employee:
    pass