The Python 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
The Python 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 ValueError
:
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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