Invalid literal for int error in Python
David Y.
—The Problem
My Python script fails with this error:
ValueError: invalid literal for int() with base 10: ''.
What causes this and how do I fix it?
The Solution
This error message arises from a failure to convert an empty string ('') to an integer. This might arise in the following script if the user presses Enter without providing any input:
user_input = input("Enter a whole number: ") print(f"Your number is 1 smaller than {1 + int(user_input)}")
To prevent this error, we should check that our string is not empty before passing it to int() for conversion:
user_input = input("Enter a whole number: ") try: print(f"Your number is 1 smaller than {1 + int(user_input)}") except ValueError: print("Please provide a valid number.")
A similar error might arise if the user provides a number with decimal places, such as 1.0. We can avoid this error by converting the string to a float before converting it to an integer:
user_input = input("Enter a whole number (non-whole numbers will be rounded down): ") try: print(f"Your number is 1 smaller than {1 + int(float(user_input))}") except ValueError: print("Please provide a valid number.")
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