d = input("1 - to enter expression; 2 - to enter text; 3 - to exit. ")
try:
d = int(d)
except ValueError:
d = 3 # the default value
Python.org
discuss.python.org › ideas
Add a default option to int() to use if conversion fails - Ideas - Discussions on Python.org
October 29, 2020 - Many times I have found myself writing code to convert strings containing user input, regex matches etc. to other types such as integers. To handle edge cases in which int(x) raises a ValueError, this usually involves having to write code like: x = int(user_input) if user_input else 0 or matches = re.match(r'(.*):(\w*)', data) try: y = int(matches.group(0)) except ValueError: y = 1 try: z = int(matches.group(1)) except ValueError: z = 10 What do people think of adding a keyw...
Real Python
realpython.com › convert-python-string-to-int
How to Convert a Python String to int – Real Python
January 16, 2021 - One good safeguard for this behavior is to always define your string representations using explicit bases: ... >>> int("0b11010010") Traceback (most recent call last): File "<stdin>", line 1, in <module> ValueError: invalid literal for int() with base 10: '0b11010010'
HowDev
how.dev › answers › how-to-convert-a-string-to-an-int-in-python
How to convert a string to an int in Python
The general syntax for the int() method is as follows: ... base: This is an optional parameter that specifies the number system. The default value is 10 which represents a decimal number.
Python Geeks
pythongeeks.org › python geeks › learn python › convert string to int in python
Convert String to int in Python - Python Geeks
December 31, 2025 - base: This parameter is optional and represents the number system to which the string belongs. The default value is 10. When the string contains numerical characters, the int() function converts the string to an integer without any issues.
Reddit
reddit.com › r/learnpython › why is base=10 the default for int()?
r/learnpython on Reddit: Why is base=10 the default for int()?
November 11, 2022 -
I was confused by the fact that int("012") equals 12 but int("0o012") results in an error. I would have expected the opposite. Reading the documentation for int() I learned that if the base is set to zero int() the input is treated like a literal int (e.g. int("0o012") = 10).
Intuatively I would expect int() to treat input as a literal interger in Python and that it should know "0o012" is base 8 just like if I used as a literal.
Why would the default be base = 10? Except for the leading 0 case doesn't base = 0 cover all base = 10 cases, plus lets you use "0b", "0o", and"0x".
My question is why the default value for base inint() is 10 rather than 0 which seems to be the more.
Top answer 1 of 5
7
My guess would be that int() originally did not take the base parameter, it simply converted integers in base 10, and when the new parameter was added the previous behaviour was preserved for legacy reasons. Looking at the Python 1.5 docs seems to confirm this. https://docs.python.org/release/1.5.2p2/lib/built-in-funcs.html
2 of 5
3
The doc for int() says: class int(x=0, /) class int(x, /, base=10) If "x" is not a number or if "base" is given, then "x" must be a string, bytes, or bytearray instance representing an integer literal in radix "base". Since you pased an x value the base defaults to 10, so passing the string "0o012" is invalid because the base is 10. If you set the base to 8 it works fine: x = int("0o012", base=8) print(x) #>> 10 Why would the default be base = 10? Because that's the most common case for converting a string to an integer.
Top answer 1 of 6
77
If you want a one-liner like you've attempted, go with this:
variable = int(stringToInt) if stringToInt else None
This will assign variable to int(stringToInt) only if stringToInt is not empty AND is "numeric". If, for example stringToInt is 'mystring', a ValueError will be raised. If stringToInt is empty (''), it will assign variable to None.
To avoid ValueErrors, use a try-except:
try:
variable = int(stringToInt)
except ValueError:
variable = None
2 of 6
31
I think this is the clearest way:
variable = int(stringToInt) if stringToInt.isdigit() else None
LabEx
labex.io › tutorials › python-how-to-handle-string-to-integer-conversion-errors-in-python-417967
How to handle string to integer conversion errors in Python | LabEx
One way to handle string to integer conversion errors is to provide a default value to be used if the conversion fails. You can do this by using the int() function with an optional third argument, which specifies the default value to be returned ...
Pi My Life Up
pimylifeup.com › home › convert a string to an integer in python
Convert a String to an Integer in Python - Pi My Life Up
April 9, 2022 - The first method sets the base value on the int() function to 16 (hex). Remember that the function’s second parameter allows you to set the baser number. This method is the best when you expect your string always contains a hexadecimal number.
freeCodeCamp
freecodecamp.org › news › python-convert-string-to-int-how-to-cast-a-string-in-python
Python Convert String to Int – How to Cast a String in Python
November 29, 2021 - To convert, or cast, a string to an integer in Python, you use the int() built-in function. The function takes in as a parameter the initial string you want to convert, and returns the integer equivalent of the value you passed.
w3resource
w3resource.com › python › built-in-function › int.php
Python int() function - w3resource
The int() function converts the specified value into an integer number. The int() function returns an integer object constructed from a number or string x, or return 0 if no arguments are given.
Linuxize
linuxize.com › home › python › how to convert string into integer in python
How to Convert String into Integer in Python | Linuxize
November 25, 2020 - It takes the following form: ... base - It represents the numeral system of the first argument. Its value can be 0 and 2–36. This argument is optional. If no base is given, the default is 10 (decimal integer).
SkillReactor Blog
skillreactor.io › home › converting python string to int: easy guide
Converting Python String to Int: Easy Guide - SkillReactor Blog
April 5, 2024 - Overall, handling invalid conversions is crucial to working with string-to-integer conversions in Python. We can create more reliable and resilient code by implementing proper error-handling strategies and incorporating data validation, try-except blocks, default values, and robust error reporting.
GeeksforGeeks
geeksforgeeks.org › how-to-convert-string-to-integer-in-python
How to convert string to integer in Python? | GeeksforGeeks
July 10, 2020 - Let's consider an example to understand it better, suppose you want to change the value of the string every time you print the string like you want to print "hello <name> welcome to geeks for ... In Python, a string of required formatting can be achieved by different methods. Some of them are; 1) Using % 2) Using {} 3) Using Template Strings In this article the formatting using % is discussed. The formatting using % is similar to that of 'printf' in C programming language. %d - integer %f -
Top answer 1 of 16
3116
>>> a = "545.2222"
>>> float(a)
545.22220000000004
>>> int(float(a))
545
2 of 16
605
Python2 method to check if a string is a float:
def is_float(value):
if value is None:
return False
try:
float(value)
return True
except:
return False
For the Python3 version of is_float see: Checking if a string can be converted to float in Python
A longer and more accurate name for this function could be: is_convertible_to_float(value)
What is, and is not a float in Python may surprise you:
The below unit tests were done using python2. Check it that Python3 has different behavior for what strings are convertable to float. One confounding difference is that any number of interior underscores are now allowed: (float("1_3.4") == float(13.4)) is True
val is_float(val) Note
-------------------- ---------- --------------------------------
"" False Blank string
"127" True Passed string
True True Pure sweet Truth
"True" False Vile contemptible lie
False True So false it becomes true
"123.456" True Decimal
" -127 " True Spaces trimmed
"\t\n12\r\n" True whitespace ignored
"NaN" True Not a number
"NaNanananaBATMAN" False I am Batman
"-iNF" True Negative infinity
"123.E4" True Exponential notation
".1" True mantissa only
"1_2_3.4" False Underscores not allowed
"12 34" False Spaces not allowed on interior
"1,234" False Commas gtfo
u'\x30' True Unicode is fine.
"NULL" False Null is not special
0x3fade True Hexadecimal
"6e7777777777777" True Shrunk to infinity
"1.797693e+308" True This is max value
"infinity" True Same as inf
"infinityandBEYOND" False Extra characters wreck it
"12.34.56" False Only one dot allowed
u'四' False Japanese '4' is not a float.
"#56" False Pound sign
"56%" False Percent of what?
"0E0" True Exponential, move dot 0 places
0**0 True 0___0 Exponentiation
"-5e-5" True Raise to a negative number
"+1e1" True Plus is OK with exponent
"+1e1^5" False Fancy exponent not interpreted
"+1e1.3" False No decimals in exponent
"-+1" False Make up your mind
"(1)" False Parenthesis is bad
You think you know what numbers are? You are not so good as you think! Not big surprise.
Don't use this code on life-critical software!
Catching broad exceptions this way, killing canaries and gobbling the exception creates a tiny chance that a valid float as string will return false. The float(...) line of code can failed for any of a thousand reasons that have nothing to do with the contents of the string. But if you're writing life-critical software in a duck-typing prototype language like Python, then you've got much larger problems.
DigitalOcean
digitalocean.com › community › tutorials › python-string-to-int-int-to-string
Python String to Int, Int to String | DigitalOcean
August 4, 2022 - In our previous tutorial we learned about Python List append function. If you read our previous tutorials, you may notice that at some time we used this conversion. Actually, this is necessary in many cases. For example, you are reading some data from a file, then it will be in String format and you will have to convert String to an int.
Cherry Servers
cherryservers.com › home › blog › cloud computing › how to convert string to int in python | comprehensive guide
How to Convert String to int in Python? | Cherry Servers
November 7, 2025 - Converting string data to integers ... working with databases. ... This is the most common method for converting strings into integers in Python. It's a constructor of the built-in int class rather than a function. When you call the int() constructor, a new int object is created. It has the following syntax. As you can see, the default base is 10. ... We can easily pass a string value and convert ...
Career Karma
careerkarma.com › blog › python › python string to int() and int to string tutorial: type conversion in python
Python String to Int() and Int to String Tutorial: Type Conversion in Python
December 1, 2023 - We’ve successfully converted our integer to a string using str(). Both values are now strings, which means that we can now concatenate the message Your age is: with the user’s age. Suppose we have a list of strings that contains the grades students have earned in a computer science class. We want to convert every grade in our list into an integer. To do this, we can use a Python list comprehension.
DigitalOcean
digitalocean.com › community › tutorials › how-to-convert-strings-to-integers-in-python-3
How To Convert Strings to Integers in Python 3 | DigitalOcean
September 3, 2020 - Let’s modify the code to include the int() method that will convert the strings to integers, and allow us to do math with these values that were originally strings. lines_yesterday = "50" lines_today = "108" lines_more = int(lines_today) - int(lines_yesterday) print(lines_more) ...
Top answer 1 of 3
7
You can't really specify it directly in the argument field, but you can convert it right after the function declaration:
def profile(request, pk=0):
pk = int(pk)
#to do
It will throw an error if the passed value for pk cannot be converted to an int
EDIT: I spoke too soon, apparently you can do exactly as you did, just change things around:
def profile(request, pk: int = 0):
#to do
BTW: I just did a quick research for "specify type of argument python". Please try to research easy things like so first before asking a question, you'll get an answer quicker :)
2 of 3
0
My code works for any input type of pk: integer, string with integer, string without integer
import re
def intCheck(pk):
contains_number = bool(re.search(r'\d', pk))
if contains_number:
return int(re.search(r'\d+', pk).group())
else:
return 0
def profile(request, pk=0):
pk = intCheck(pk)
print(request + " " + str(pk))
profile('request', "232")
profile('request', 123)
profile('request', "no number")
Output:
request 232
request 123
request 0