python empty exception string

stackoverflow.com › questions › 19579997 › how-to-catch-empty-user-input-using-a-try-and-except-in-python

How to catch empty user input using a try and except in python? - Stack Overflow

1 of 2

8

If you literally want to raise an exception only on the empty string, you'll need to do that manually:

try:
    user_input = input() # raw_input in Python 2.x
    if not user_input:
        raise ValueError('empty string')
except ValueError as e:
    print(e)

But that "integer input" part of the comment makes me think what you really want is to raise an exception on anything other than an integer, including but not limited to the empty string.

If so, open up your interactive interpreter and see what happens when you type things like int('2'), int('abc'), int(''), etc., and the answer should be pretty obvious.

But then how do you distinguish an empty string from something different? Simple: Just do the user_input = input() before the try, and check whether user_input is empty within the except. (You put if statements inside except handlers all the time in real code, e.g., to distinguish an OSError with an EINTR errno from one with a different errno.)

2 of 2

0

try:
    input = raw_input('input: ')
    if int(input):
        ......
except ValueError:
    if not input:
        raise ValueError('empty string')
    else:
        raise ValueError('not int')

try this, both empty string and non-int can be detected. Next time, be specific of the question.

docs.python.org › 3 › library › exceptions.html

Built-in Exceptions — Python 3.14.5 documentation

It is not meant to be directly inherited by user-defined classes (for that, use Exception). If str() is called on an instance of this class, the representation of the argument(s) to the instance are returned, or the empty string when there were no ...

stackoverflow.com › questions › 17178186 › empty-error-message-in-python

exception - empty error message in python - Stack Overflow

daniweb.com › programming › software-development › threads › 381248 › using-try-except-to-catch-a-blank-input

1 of 4

22

This means the exception has no message attached. Print the exception type:

print repr(e)

You may also want to print the traceback:

import traceback

# ...
except BaseException as e:
    traceback.print_exc()

You want to avoid catching BaseException however, this is no better than a blanket except: statement. Catch more specific exceptions instead.

2 of 4

7

The following produces a blank line of output:

try:
    raise Exception()
except BaseException, e:
    print str(e)

Use repr(e) to see what the exception is that was raised.

DaniWeb

python - Using Try, Except to catch a blank input [SOLVED] | DaniWeb

In python 3, after result = input(prompt) , result is a string in the python sense (an instance of the datatype 'str'). Examples of strings are · "" # the empty string " " # a string of white space "3.14159" # a string with the representation … — Gribouillis 1,391 Jump to Post · You can pass the acceptable values to the checkInput() function and let it do the work. For the getFloat() function, use a try/except to test for correct input.

stackoverflow.com › questions › 31230229 › memoryerrors-message-as-str-is-empty-in-python

exception - MemoryError's message as str is empty in Python - Stack Overflow

w3resource.com › python-exercises › extended-data-types › python-extended-data-types-none-exercise-1.php

1 of 3

5

So you probably want to print the name of the exception class:

Copytry:
    np.arange(1e10)
except Exception as e:   #not catch...
    print(str(e.__class__.__name__))
    print("Catched!")

Using str(e) only prints the "message" of the exception, which in your case was empty.

Note that you can obtain the arguments passed to the exception constructor via the args attribute:

CopyIn [4]: try:
   ...:     raise ValueError(1,2,3)
   ...: except ValueError as e:
   ...:     print('arguments:', e.args)
arguments: (1, 2, 3)

2 of 3

4

When call str(e) it returns the message of the Exception. Take an example -

CopyNameError: name 'a' is not defined
^          ^
name       message

The part before : is the name of the exception, whereas the part after it is the message (arguments).

In the case of MemoryError , as you can see in your example -

CopyMemoryError:

does not have an error message , only the name of the exception , hence you get the empty string.

I am not sure if there are other Exceptions that do not have an exception, but I believe it would be very rare to find such exceptions. Maybe you can print both the exception's name as well as the message , if you really want to take care of the MemoryError (and maybe other such rare exceptions without messages) , something like -

Copyprint(type(e).__name__ , ':', str(e))

w3resource

Python function to handle empty strings

August 11, 2025 - Write a Python function that takes a string as input and returns "None" if the string is empty, otherwise it returns the given string. ... def check_string(input_string): if not input_string: return "None" return input_string def main(): try: ...

CopyProgramming

copyprogramming.com › howto › python-empty-list-exception

Python: Exception Raised When Using an Empty List in Python

April 9, 2023 - Empty tuple as argument to except in python, The answer is 1: no exceptions, in Python 2 and in Python 3. exceptions = () try: a = 1 / 0 except exceptions as e: print ("the answer is 2") Traceback (most recent call last): File "<pyshell#38>", line 2, in <module> a = 1 / 0 ZeroDivisionError: integer division or modulo by zero. If you want to the … ... In the try clause, I am assigning values to multiple variables . However, I need an except clause that sets an empty string only for the variables that are unavailable.

TutorialsPoint

tutorialspoint.com › What-is-the-best-way-to-handle-list-empty-exception-in-Python

What is the best way to handle list empty exception in Python?

December 19, 2019 - a=[1,2,3] while True: try: b=a.pop() print (b) except (IndexError): break

CodeQL

codeql.github.com › codeql-query-help › python › py-empty-except

Empty except — CodeQL query help documentation

An empty except block may be an indication that the programmer intended to handle the exception, but never wrote the code to do so. Ensure all exceptions are handled correctly. In this example, the program keeps running with the same privileges if it fails to drop to lower privileges.

Find elsewhere

Google Bing Mojeek

docs.python.org › 3.13 › library › exceptions.html

Built-in Exceptions — Python 3.13.3 documentation

It is not meant to be directly inherited by user-defined classes (for that, use Exception). If str() is called on an instance of this class, the representation of the argument(s) to the instance are returned, or the empty string when there were no ...

University of Toronto

teach.cs.toronto.edu › ~csc148h › winter › notes › abstract-data-types › exceptions.html

3.3 Exceptions

class EmptyStackError(Exception): """Exception raised when calling pop on an empty stack.""" def __str__(self) -> str: """Return a string representation of this error.""" return 'You called pop on an empty stack.

stackoverflow.com › questions › 24249298 › try-except-clause-with-an-empty-except-code

python - Try-except clause with an empty except code - Stack Overflow

1 of 3

110

try:
    do_something()
except:
    pass

You will use the pass statement.

The pass statement does nothing. It can be used when a statement is required syntactically but the program requires no action.

2 of 3

24

Use pass:

try:
    foo()
except: 
    pass

A pass is just a placeholder for nothing, it just passes along to prevent SyntaxErrors.

docs.python.org › 3.14 › library › exceptions.html

Built-in Exceptions — Python 3.14.0b1 documentation

It is not meant to be directly inherited by user-defined classes (for that, use Exception). If str() is called on an instance of this class, the representation of the argument(s) to the instance are returned, or the empty string when there were no ...

docs.python.org › 3 › library › exceptions.html

Built-in Exceptions — Python 3.14.4 documentation

It is not meant to be directly inherited by user-defined classes (for that, use Exception). If str() is called on an instance of this class, the representation of the argument(s) to the instance are returned, or the empty string when there were no ...

docs.python.org › 3 › c-api › exceptions.html

Exception Handling — Python 3.14.5 documentation

This function sets the error indicator and returns NULL. exception should be a Python exception class. The format and subsequent parameters help format the error message; they have the same meaning and values as in PyUnicode_FromFormat(). format is an ASCII-encoded string.

docs.python.org › 3.15 › library › exceptions.html

Built-in Exceptions — Python 3.15.0a2 documentation

It is not meant to be directly inherited by user-defined classes (for that, use Exception). If str() is called on an instance of this class, the representation of the argument(s) to the instance are returned, or the empty string when there were no ...

stackoverflow.com › questions › 4308182 › getting-the-exception-value-in-python

Getting the exception value in Python - Stack Overflow

1 of 7

518

use str

Copytry:
    some_method()
except Exception as e:
    s = str(e)

Also, most exception classes will have an args attribute. Often, args[0] will be an error message.

It should be noted that just using str will return an empty string if there's no error message whereas using repr as pyfunc recommends will at least display the class of the exception. My take is that if you're printing it out, it's for an end user that doesn't care what the class is and just wants an error message.

It really depends on the class of exception that you are dealing with and how it is instantiated. Did you have something in particular in mind?

2 of 7

308

Use repr() and The difference between using repr and str

Using repr:

Copy>>> try:
...     print(x)
... except Exception as e:
...     print(repr(e))
... 
NameError("name 'x' is not defined")

Using str:

Copy>>> try:
...     print(x)
... except Exception as e:
...     print(str(e))
... 
name 'x' is not defined

stackoverflow.com › questions › 33897358 › python-return-empty-value-on-exception

try catch - Python: return empty value on exception - Stack Overflow