How to check if type of a variable is string? [duplicate]

stackoverflow.com › questions › 4843173 › how-to-check-if-type-of-a-variable-is-string

In Python 3.x, the correct way to check if s is a string is

isinstance(s, str)

The bytes class isn't considered a string type in Python 3.

In Python 2.x, the correct check was

isinstance(s, basestring)

basestring is the abstract superclass of str and unicode. It can be used to test whether an object is an instance of either str or unicode.

Answer from Sven Marnach on Stack Overflow

w3schools.com › python › gloss_python_check_string.asp

Python Check In String

Remove List Duplicates Reverse ... ... To check if a certain phrase or character is present in a string, we can use the keywords in or not in....

stackoverflow.com › questions › 4843173 › how-to-check-if-type-of-a-variable-is-string

python - How to check if type of a variable is string? - Stack Overflow

In Python 3.x, the correct way to check if s is a string is

isinstance(s, str)

The bytes class isn't considered a string type in Python 3.

In Python 2.x, the correct check was

isinstance(s, basestring)

basestring is the abstract superclass of str and unicode. It can be used to test whether an object is an instance of either str or unicode.

I know this is an old topic, but being the first one shown on google and given that I don't find any of the answers satisfactory, I'll leave this here for future reference:

six is a Python 2 and 3 compatibility library which already covers this issue. You can then do something like this:

import six

if isinstance(value, six.string_types):
    pass # It's a string !!

Inspecting the code, this is what you find:

import sys

PY3 = sys.version_info[0] == 3

if PY3:
    string_types = str,
else:
    string_types = basestring,

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Discussions

How can you check if a string contains any one character from a set of characters?

There's str.isdigit() checking if a string contains digits only: >>> '44 a b'.isdigit() False >>> Combined with any, applied to each character: >>> any([c.isdigit() for c in "44 a b"]) True >>> More on reddit.com

r/learnpython

10

3

May 24, 2022

[Beginner question] How do I check if an input is a string, float, or integer in 2.7 without changing it?

One approach is to try to convert them to said types, the most critical first try: val = int(user_input) print("it's an int") except ValueError: try: val = float(user_input) print("it's a float") except ValueError: print("it's a string") Another option is to default to a float and use its is_integer to check it try: val = float(user_input) if val.is_integer(): print("it's an int") else: print("it's a float") except ValueError: print("it's a string") and just maintain that detection to know how you should round() the calculation result More on reddit.com

r/learnpython

8

1

March 15, 2020

Videos

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Identifying a Substring Within a Python String - YouTube

cs.stanford.edu › people › nick › py › python-string.html

These convenient functions return True/False depending on what appears at one end of a string. These are convenient when you need to check for something at an end, e.g. if a filename ends with '.html'. Style aside: a good example of a well-named function, making the code where it is called very readable. ... >>> 'Python'.startswith('Py') True >>> 'Python'.startswith('Px') False >>> 'resume.html'.endswith('.html') True

geeksforgeeks.org › python › python-check-if-given-string-is-numeric-or-not

Python Check If String is Number - GeeksforGeeks

July 11, 2025 - The final result is printed as "The string is not Number," since 'g' is a non-numeric character in the string. ... # Python code to check if string is numeric or not # checking for numeric characters numerics="0123456789" string="012gfg345" is_number = True for i in string: if i not in numerics: is_number = False break if is_number: print("The string is Number,") else: print("The string is not Number,")

digitalocean.com › community › tutorials › python-find-string-in-list

Python Find String in List: Methods and Examples | DigitalOcean

1 month ago - Use regular expressions only when you are matching a pattern (dates, extensions, IDs). For fixed text, plain in or str.find() is faster and easier to read. The in operator is the simplest and most common way to check whether a string is in a list, and it is the fastest choice for a one-time check.

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

string — Common string operations

Implement checking for unused arguments if desired. The arguments to this function is the set of all argument keys that were actually referred to in the format string (integers for positional arguments, and strings for named arguments), and a reference to the args and kwargs that was passed ...

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bottega.devcamp.com › full-stack-development-javascript-python › guide › how-to-check-value-included-python-string-list

How to Check if a Value is Included in a Python String or List

So there are a number of ways around this that you're going to find in Python. One of the common ones is to simply call the lower function on each one of these elements so if you want to perform a case-insensitive search you can just call whatever the variable is that contains a string and say I want you to take all of the values and change them to lowercase and the same thing with this word.

geeksforgeeks.org › python › check-if-string-contains-substring-in-python

Check if String Contains Substring in Python - GeeksforGeeks

December 20, 2025 - The operator.contains() function checks for substring presence in a string programmatically. It provides the same result as the in operator but belongs to Python’s operator module, making it useful in functional programming contexts.

reddit.com › r/learnpython › how can you check if a string contains any one character from a set of characters?

r/learnpython on Reddit: How can you check if a string contains any one character from a set of characters?

May 24, 2022 -

Is there some easy, built-in way to check if a given string contains at least one single digit, 0-9? Everything I'm searching talks about the in operator or the find method, but those seem to require that you already know which digit you are looking for.

I'm leaning toward using an RE, but I wanted to know if there was a simpler way first.

Examples that would evaluate to true would be:

'44 a b'
'aa ba 5'
'45 187'

and false would be any string without at least one digit.

I figure I can just try to match it with \d+, but I don't want to rely on REs too much, even though I find them fun!

Thanks!

There's str.isdigit() checking if a string contains digits only: >>> '44 a b'.isdigit() False >>> Combined with any, applied to each character: >>> any([c.isdigit() for c in "44 a b"]) True >>>

Returns True if there is a digit and False if no digit: >>> not set('44 a a b').isdisjoint('1234567890') True >>> not set('testing').isdisjoint('1234567890') False >>> or >>> bool(set('3 a a b') & set('1234567890')) True >>> bool(set('testing') & set('1234567890')) False >>>

codecademy.com › docs › python › strings › .startswith()

Python | Strings | .startswith() | Codecademy

April 17, 2025 - The .startswith() method in Python checks whether a string begins with a specified value and returns True if it does. Otherwise, it returns False.

Python documentation

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

Built-in Types — Python 3.14.6 documentation

Some operations are supported by several object types; in particular, practically all objects can be compared for equality, tested for truth value, and converted to a string (with the repr() function or the slightly different str() function).

w3schools.com › python › python_strings.asp

Learn more about If statements in our Python If...Else chapter. To check if a certain phrase or character is NOT present in a string, we can use the keyword not in.

stackoverflow.com › questions › 1303243 › how-to-find-out-if-a-python-object-is-a-string

How to find out if a Python object is a string? - Stack Overflow

Python 2

Use isinstance(obj, basestring) for an object-to-test obj.

Docs.

Python 3

In Python 3.x basestring is not available anymore, as str is the sole string type (with the semantics of Python 2.x's unicode).

So the check in Python 3.x is just:

isinstance(obj_to_test, str)

This follows the fix of the official 2to3 conversion tool: converting basestring to str.

geeksforgeeks.org › python › check-if-a-variable-is-string-python

How to Check if a Variable is a String - Python - GeeksforGeeks

This follows Python’s “try it and see” style and also called duck typing. ... Explanation: This code attempts to call the lower() method on a. If a is a string, the method will work, and it prints "Yes". If a does not have a lower() method (e.g., it's not a string), it raises an AttributeError, and the code prints "No". This way uses regular expressions to check if the variable is a string and optionally matches a specific pattern.

Published July 11, 2025

digitalocean.com › community › tutorials › python-string-comparison

Python Compare Strings: Methods, Operators & Best Practices | DigitalOcean

June 15, 2026 - You can compare strings in Python using the equality (==) and comparison (<, >, !=, <=, >=) operators. There are no special methods to compare two strings. The == operator is the right choice for almost every string comparison: it checks whether two strings contain the same characters, and ...

sentry.io › sentry answers › python › check if a string is empty in python

Python Truth Value Testing for Empty String Checks | Sentry

2 weeks ago - Check if a Python string is empty using truth value testing with the not operator, strict comparison with == "", or strip() to handle whitespace-only strings

realpython.com › python-string-contains-substring

How to Check if a Python String Contains a Substring – Real Python

December 1, 2024 - In Python, this is the recommended way to confirm the existence of a substring in a string: ... >>> raw_file_content = """Hi there and welcome. ... This is a special hidden file with a SECRET secret. ... I don't want to tell you The Secret, ... but I do want to secretly tell you that I have one.""" >>> "secret" in raw_file_content True · The in membership operator gives you a quick and readable way to check whether a substring is present in a string.

reddit.com › r/learnpython › [beginner question] how do i check if an input is a string, float, or integer in 2.7 without changing it?

r/learnpython on Reddit: [Beginner question] How do I check if an input is a string, float, or integer in 2.7 without changing it?

March 15, 2020 -

Hello! I recently decided to pick up python 2.7 for a project in my computer science class, but my area has been quarantined by covid-19 and I'm unable to ask my teacher for any help. I'm making a basic unit-conversion calculator, and I'd like to be able to tell what a user is inputting, without changing it. For example, if they put in a string, it would display a message such as "Sorry, only numbers are allowed" and allows the user to try again. I'm using the raw_input() function to get the input, but idk how to discern strings, floats, and integers.

One approach is to try to convert them to said types, the most critical first try: val = int(user_input) print("it's an int") except ValueError: try: val = float(user_input) print("it's a float") except ValueError: print("it's a string") Another option is to default to a float and use its is_integer to check it try: val = float(user_input) if val.is_integer(): print("it's an int") else: print("it's a float") except ValueError: print("it's a string") and just maintain that detection to know how you should round() the calculation result

https://realpython.com/python-data-types/

sololearn.com › en › Discuss › 1826264 › how-to-check-whether-an-object-is-string-or-integer-in-python-also-using-if-else-to-determine-them

How to check whether an object is string or integer ...

June 2, 2019 - sl_scroll_/de/Discuss/1953300/python-artificial-intelligence-Pending

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