Software Development

Why am I getting ValueError invalid literal for int with base 10 when converting user input?

JE Asked by Jennifer Slate · 14-06-2024
0 upvotes 14,242 views 0 comments
The question

I am writing a simple Python script where I ask the user for their age and try to convert it to an integer using int(). However, if the user accidentally types a decimal point or a letter, the whole program crashes with this base 10 error. How can I handle this so my code doesn't break every time? 

3 answers

0
MA
Answered on 16-06-2024

The error occurs because the int() function expects a string that looks exactly like a whole number. If there is a decimal (like "25.0") or a character (like "25a"), Python doesn't know how to convert it to base 10. To fix this in a production environment, you should use a try-except block. This allows you to catch the ValueError and prompt the user again or provide a default value. For instance, try: age = int(input()) except ValueError: print("Please enter a valid whole number"). This is a fundamental practice in software development to ensure your applications are robust and user-friendly. 

0
TH
Answered on 17-06-2024

Are you specifically dealing with strings that might contain floats, like "10.5"? Sometimes it is better to convert to a float first and then to an integer to avoid this literal error. POSTED BY: Thomas Miller DATE: 17-06-2023

RO 18-06-2024

That’s a good point, Thomas. If I use int(float("10.5")), will that just truncate the decimal or will it round it to the nearest whole number? I need to make sure I don't lose data accuracy during this conversion if I'm calculating financial totals in my script.

0
BA
Answered on 19-06-2024

You can also use the .isdigit() method on your string before calling int(). This checks if the string contains only numeric digits, preventing the error before it happens. 

JE 20-06-2024

I agree with Barbara. Using .isdigit() is a very clean way to validate input before processing, though it won't work for negative numbers since the minus sign isn't a digit!

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