Use try/except.
>>> while True:
... try:
... x = int(raw_input("Please enter a number: "))
... break
... except ValueError:
... print "Oops! That was no valid number. Try again..."
...
Python documentation
docs.python.org › 3 › tutorial › errors.html
8. Errors and Exceptions — Python 3.14.3 documentation
import sys try: f = open('myfile.txt') s = f.readline() i = int(s.strip()) except OSError as err: print("OS error:", err) except ValueError: print("Could not convert data to an integer.") except Exception as err: print(f"Unexpected {err=}, {type(err)=}") raise · The try … except statement has an optional else clause, which, when present, must follow all except clauses. It is useful for code that must be executed if the try clause does not raise an exception.
Python.org
discuss.python.org › python help
Calling "if" statement on errors (TypeError, ValueError, SyntaxError...) - Python Help - Discussions on Python.org
I’m creating an operating system within python. I’ve created the init system, the workflows, the plans… The only thing i need to do now is to make a valid shell I want to integrate Bash and Python together, so I’d need a way to have an “if” statement for example: text = input("PySH> ") if input == SyntaxError: # execute this That’s my crude explanation of what my problem is
Published April 20, 2021
Python: if error raised I want to stay in script - Stack Overflow
I am doing some practice problems from online with python and I have a question about how to stay in a script if an error is raised. For example, I want to read in values from prompt and compare th... More on stackoverflow.com
Python: else ValueError: (Specifically ValueError In This Case) - Stack Overflow
I have a question which is unrelated to my code. I'm just curious. Why is it that I (I don't know about you) can only use a ValueError with a try and except loop? for example: print("What is 1 + 1... More on stackoverflow.com
Explain Python ValueError Exception Handling (With Real Examples & Best Practices)
Learn what Python ValueError means, why it occurs, and how to fix it with practical examples, best practices, and real-world use cases. More on accuweb.cloud
1
January 15, 2024except VS except valueError: what's the difference?
It's always better to handle errors that you expect so that you don't bypass ones you don't expect. Except without an error afterwards bypasses all errors. except ValueError will only bypass a ValueError and therefore is better error handling. If a SyntaxError happens, then it won't be bypassed. This is good because it may not be expected and therefore you would not want to propagate further More on reddit.com
6
1
May 19, 2020Videos
DigitalOcean
digitalocean.com › community › tutorials › python-valueerror-exception-handling-examples
Python ValueError Exception Handling: Examples & Fixes | DigitalOcean
August 3, 2022 - Here is a simple example to handle ValueError exception using try-except block.
W3Schools
w3schools.com › python › ref_exception_valueerror.asp
Python ValueError Exception
Python Examples Python Compiler ... Python Certificate Python Training ... The ValueError exception occurs if a function receives a value of wrong type....
Top answer 1 of 7
27
Use try/except.
>>> while True:
... try:
... x = int(raw_input("Please enter a number: "))
... break
... except ValueError:
... print "Oops! That was no valid number. Try again..."
...
2 of 7
12
success = false
while not success:
try:
value = raw_input('please enter an integer')
int(value)
success = true
except:
pass
Educative
educative.io › answers › what-is-valueerror-in-python
What is ValueError in Python?
ValueError in Python is raised when a user gives an invalid value to a function but is of a valid argument.
Turing
turing.com › kb › valueerror-in-python-and-how-to-fix
What is ValueError in Python & How to fix it
Even though the value is the correct argument, it typically happens in mathematical processes that call for a specific kind of value. When an object is given the incorrect value, the Python ValueError is raised. This may occur if the value is ...
Rollbar
rollbar.com › home › how to fix valueerror exceptions in python
How to Fix ValueError Exceptions in Python | Rollbar
June 24, 2024 - The Python ValueError is raised when an object is assigned the right data type but the wrong value for a certain operation. Some of the most common scenarios where this can happen are: If the value is invalid for the operation.
Real Python
realpython.com › ref › builtin-exceptions › valueerror
ValueError | Python’s Built-in Exceptions – Real Python
Python · >>> user_input = "one" >>> try: ... number = int(user_input) ... except ValueError: ... print(f"Could not convert '{user_input}' to an integer.") ... Could not convert 'one' to an integer. If you’re writing a function that demands certain value constraints, you can raise ValueError to enforce them: Python ·
Top answer 1 of 3
3
The SyntaxError in the second example comes from the fact, that else needs no condition. The first example is totally ok.
Still better, keep the try-block as short as possible:
print("What is 1 + 1?")
while True:
try:
UserInput = int(input(("Your answer here:"))
except ValueError:
print("That is not a number. Try again!")
else:
if UserInput == 2:
print("Congratulations you are correct!")
break
else:
print("That is incorrect. Try again!")
2 of 3
2
try and except are a form of control flow. Essentially, it means try to run this code, except if an exception occurs (such as ValueError) do something else.
if and else are another form of control flow. Together, they mean if a condition is true, do something; else, do something else.
An exception occurring is not a condition, and thus it would not make sense to use else with an exception like ValueError. Instead, you want to use the try/except block.
Python
docs.python.org › 3 › library › exceptions.html
Built-in Exceptions — Python 3.14.4 documentation
If an object is meant to support a given operation but has not yet provided an implementation, NotImplementedError is the proper exception to raise. Passing arguments of the wrong type (e.g. passing a list when an int is expected) should result in a TypeError, but passing arguments with the wrong value (e.g. a number outside expected boundaries) should result in a ValueError...
Accuweb
accuweb.cloud › home › explain python valueerror exception handling (with real examples & best practices)
Explain Python ValueError Exception Handling (With Real Examples & Best Practices)
January 15, 2024 - Python ValueError is raised when a function receives a value of the correct type but an inappropriate or invalid value.
Carleton University
cs.carleton.edu › cs_comps › 1213 › pylearn › final_results › encyclopedia › valueError.html
Error Encyclopedia | Value Error
>>> a, b, c, d = [3, 4, 5] Traceback (most recent call last): File "<stdin>", line 1, in <module> ValueError: need more than 3 values to unpack · This returns a value error, because there are too few values on the right-hand side for Python to ‘unpack.’ When Python tries to assign ‘d’ to a value on the right-hand side, it is unable to find any matching value to ‘unpack’, and thus throws a ValueError.
Linux Hint
linuxhint.com › handling-value-error-exception-python
Handling the ValueError Exception in Python – Linux Hint
try: #Open the file for reading fh = open('sales.txt') #Define while loop to read file line by line while fh: #Convert the line into the integer value = int(fh.readline()) #Print the value print(value) except (ValueError, IOError): ''' Print the error message if the file is unable to read or the file contains any string data ''' print("ValueError or IOError has occurred.") ... The following output will appear after executing the above script. Here, the ValueError has been generated because the sales.txt file contains alphabetic characters at line number 6. Create a Python file with the following script that will take a number from the command-line argument value.
Reddit
reddit.com › r/learnpython › except vs except valueerror: what's the difference?
r/learnpython on Reddit: except VS except valueError: what's the difference?
May 19, 2020 -
Hi there,
I've been learning Python for some months now (still a beginner though!) and so far I encountered no issues when using a simple except in errors handling. But I came across except valueError many times in other people's codes, and I was wondering what was the difference between these two.
All I could find on the Internet was the use of the except valueError when raising an error, but I don't think I understood how it's different from except alone. Also it seems like this latter is barely mentioned anywhere I looked...
Any help appreciated!
Top answer 1 of 5
3
It's always better to handle errors that you expect so that you don't bypass ones you don't expect. Except without an error afterwards bypasses all errors. except ValueError will only bypass a ValueError and therefore is better error handling. If a SyntaxError happens, then it won't be bypassed. This is good because it may not be expected and therefore you would not want to propagate further
2 of 5
2
except by itself captures every type of exception; if you specify an exception class, then your block only captures exceptions of that type. It's generally a good practice to capture the smallest number of exceptions possible. Only capture the ones you know how to handle.
iO Flood
ioflood.com › blog › python-valueerror
[SOLVED] Python ValueError | Causes and Solutions
January 30, 2024 - A ValueError in Python is raised when a function receives an argument of the correct type but an inappropriate value. To handle it, you can use a try-except block to catch the error and handle it appropriately.
GeeksforGeeks
geeksforgeeks.org › python › how-to-fix-valueerror-exceptions-in-python
How To Fix Valueerror Exceptions In Python - GeeksforGeeks
July 23, 2025 - Below, are the ways to solve the Valueerror Exceptions in Python ... Below, code attempts to convert a numeric value (`a`) and a non-numeric string (`b`) to floats using the `float()` function. A try-except block is used to catch a potential `ValueError` that may occur during the conversion of the non-numeric string. If such an error occurs, it prints a clear error message indicating the inability to convert the string to a float.
Medium
infotechdreamer.medium.com › valueerror-in-python-what-it-is-how-to-fix-63251108438c
ValueError in Python: What it is & How To Fix? | by Infotechdreamer | Medium
July 25, 2023 - A ValueError is a type of Python error that occurs when a function or operation receives an argument that has the right type but an inappropriate value. Here are some common examples of ValueErrors in Python: A function might expect an integer, ...
w3resource
w3resource.com › python-exercises › python-exception-handling-exercise-2.php
Python Program for valid integer input
July 9, 2025 - If the conversion fails and a ValueError exception is raised, the program jumps to the except block. In the except block, we catch the ValueError exception and print an error message indicating the input is invalid. ... Input an integer: abc Error: Invalid input, input a valid integer. Input value: None · Input an integer: 10.06 Error: Invalid input, input a valid integer. Input value: None ... Write a Python program that repeatedly prompts the user for input until a valid integer is entered, raising ValueError for invalid inputs.
Reddit
reddit.com › r/learnpython › what's the difference between a typeerror and valueerror?
r/learnpython on Reddit: What's the difference between a TypeError and ValueError?
September 21, 2022 -
In this example:
x = int(input("x: "))
print(f'x = {x}')if the input is a string, a ValueError is raised. Why not a TypeError? An invalid data type is inputted after all.
Top answer 1 of 5
17
Just to make things clear. input("x: ") always returns a string. It can be "123" or "bananas". In the first case, it can be converted to an integer. In the second case, it cannot, and a ValueError is raised. But in either case the type is fine for the int function. So this is a value error, not a type error.
2 of 5
11
TypeError refers to a situation where something like a function is expecting to get one type as an argument, but it's given something else instead. For instance, it could be expecting a list, but given an integer. ValueError refers to a situation where the type of the aforementioned argument is okay, but the actual content doesn't match some agreed-upon rule. In this case, int is expecting a string or numeric type as an argument, which is fine as input always returns a string, but it expects that string to only have digits (which can be surrounded by whitespace). If you give it a string with other characters, it freaks out because it has no idea how to create an integer out of those (unless you set the number base to something like 16, in which case some are okay, but you'd end up with different results).