ValueError is an exception that occurs when a function receives an argument of the correct data type but an inappropriate value. This error usually occurs in mathematical operations that require a certain kind of value.
What Causes ValueError
ValueError is raised when the wrong value is assigned to an object. This can happen if the value is invalid for a given operation, or if the value does not exist. For example, if a negative integer is passed to a square root operation, a
ValueError is raised.
Python ValueError Example
Here’s an example of a Python
ValueError raised when trying to perform a square root operation on a negative number:
import math math.sqrt(-100)
In the above example, a negative integer is passed to the
math.sqrt() function. Since the function expects a positive integer, running the above code raises a
Traceback (most recent call last): File "test.py", line 3, in <module> math.sqrt(-100) ValueError: math domain error
How to Fix ValueError Exceptions in Python
To resolve the
ValueError in Python code, a try-except block can be used. The lines of code that can throw the
ValueError should be placed in the
try block, and the
except block can catch and handle the error.
Using the above approach, the previous example can be updated to handle the error:
import math try: math.sqrt(-100) except ValueError: print('Positive number expected for square root operation')
Here, a check is performed for the
ValueError using the try-except block. When the above code is executed, the
except block catches the
ValueError and handles it, producing the following output:
Positive number expected for square root operation
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