Invalid literal for int() with base 10 | Error and Resolution
Python is a special language which allows you to handle errors and exceptions very well. With thousands of known exceptions and ability to handle each of them, all the errors are easily removable from the code. Keeping this in mind, we’ll discuss about the invalid literal for int() error in python.
Invalid literal for int() with base 10 is caused when you try to convert an invalid object into an integer. In Python, the int() function accepts an object and then converts it to an integer provided that it is in a readable format. So, when you try to convert a string with no integers in it, it’ll throw an error. This error belongs to the ValueError category as the value of the parameter is invalid.
Cause of invalid literal for int() with base 10 error:
ValueError in Python occurs when we one passes an inappropriate argument type. Invalid literal for int() with base 10 error is caused by passing an incorrect argument to the int() function. A ValueError is raised when we pass any string representation other than that of int.
Let us understand it in detail!
This error message informs that there is an invalid literal for an integer in base 10. This error means that the value that we have passed cannot be converted.
Let us consider an example:
It may happen that we can think that while executing the above code, the decimal part,i.e, ‘.9’ will be truncated giving the output 1. However, this does not happen as the int( ) function uses the decimal number system as its base for conversion. This means that the default base for the conversion is 10. In the decimal number system, we have numbers from 0 to 9. Thus, i nt() with base = 10 can only convert a string representation of int and not floats or chars.
Let us see a few examples where this error can occur:
Example 1:
In this example the value “pythonpool” is a string value passed to the int() method which gives rise to the error.
Example 2:
As the value we have used here is float inside string, this gives rise to invalid literal for int() error.
Example 3:
We get error in this example as we have used list inside string.
Example 4:
The error invalid literal for int() arises because we have used tuple inside string.
Example 5:
Here, we have used dictionary inside string which gives rise to the error.
Example 6:
The error arises in this code as we have used the empty string in the int() method.
Resolution to the Error: invalid literal for int() with base 10:
Using float to avoid decimal numbers:
Here, we first converted the string representation into float using the float() method. We then used the int() method to convert it into an integer.
using try-catch: to resolve invalid literal for int() with base 10
Here we have used the try-catch method to rid the invalid literal for int() with base 10 error. Basically, if the error occurs inside the try block, it is caught in the catch block, thus preventing the error.
Using isdigit():
In this method, we first make sure that the content inside the string is integer using the isdigit() method. As a result, the error does not occur.
Using isnumeric():
Isnumeric method of the string returns the boolean stating if the string is a number. If the string contains a number then we’ll convert it to int, else not.
Conclusion:
With this, we come to an end to this article. This was an easy way to get rid of the value error in Python. If the above method does not work, then one must if the string and make sure that it does not contain any letter.
However, if you have any doubts or questions, do let me know in the comment section below. I will try to help you as soon as possible.
ValueError: Invalid Literal For int() With Base 10
Python ValueError: invalid literal for int() with base 10 is an exception which can occur when we attempt to convert a string literal to integer using int() method and the string literal contains characters other than digits. In this article, we will try to understand the reasons behind this exception and will look at different methods to avoid it in our programs.
What is “ValueError: invalid literal for int() with base 10” in Python?
A ValueError is an exception in python which occurs when an argument with the correct type but improper value is passed to a method or function.The first part of the message i.e. “ValueError” tells us that an exception has occurred because an improper value is passed as argument to the int() function. The second part of the message “invalid literal for int() with base 10” tells us that we have tried to convert an input to integer but the input has characters other than digits in the decimal number system.
Working of int() function
The int() function in python takes a string or a number as first argument and an optional argument base which denotes the number format. The base has a default value 10 which is used for decimal numbers but we can pass a different value for base such as 2 for binary number or 16 for hexadecimal number. In this article, we will use the int() function with only the first argument and the default value for base will always be zero. This can be seen in the following examples.
We can convert a floating point number to integer as given in the following example.When we convert a floating point number into integer using int() function, the digits after the decimal are dropped from the number in the output.
We can convert a string consisting of digits to an integer as given in the following example. Here the input consists of only the digits and hence it will be directly converted into an integer.
The two input types shown in the above two examples are the only input types for which int() function works properly. With other types of inputs, ValueError will be generated with the message ”invalid literal for int() with base 10” when they are passed as arguments to the int() function. Now , we will look at various types of inputs for which ValueError can be generated in the int() function.
When does “ValueError: invalid literal for int() with base 10” occur?
As discussed above, “ValueError: invalid literal for int()” with base 10 can occur when input with an inappropriate value is passed to the int() function. This can happen in the following conditions.
1.Python ValueError: invalid literal for int() with base 10 occurs when input to int() method is alphanumeric instead of numeric and hence the input cannot be converted into an integer.This can be understood with the following example.
In this example, we pass a string containing alphanumeric characters to the int() function due to which ValueError occurs showing a message “ ValueError: invalid literal for int() with base 10” in the output.
2. Python ValueError: invalid literal for int() with base 10 occurs when the input to int() function contains space characters and hence the input cannot be converted into an integer. This can be understood with the following example.
In this example, we pass a string containing space to the int() function due to which ValueError occurs showing a message “ ValueError: invalid literal for int() with base 10” in the output.
3. Python ValueError: invalid literal for int() with base 10 occurs when the input to int() function contains any punctuation marks like period “.” or comma “,”. Hence the input cannot be converted into an integer.This can be understood with the following example.
In this example, we pass a string containing period character “.” to the int() function due to which ValueError occurs showing a message “ ValueError: invalid literal for int() with base 10” in the output.
How to avoid “ValueError: invalid literal for int() with base 10”?
We can avoid the ValueError: invalid literal for int() with base 10 exception using preemptive measures to check if the input being passed to the int() function consists of only digits or not. We can use several ways to check if the input being passed to int() consists of only digits or not as follows.
1.We can use regular expressions to check if the input being passed to the int() function consists of only digits or not. If the input contains characters other than digits, we can prompt the user that the input cannot be converted to integer. Otherwise, we can proceed normally.
In the python code given below, we have defined a regular expression “[^\d]” which matches every character except digits in the decimal system. The re.search() method searches for the pattern and if the pattern is found, it returns a match object. Otherwise re.search() method returns None.
Whenever, re.search() returns None, it can be accomplished that the input has no characters other than digits and hence the input can be converted into an integer as follows.
If the input contains any character other than digits,re.search() would contain a match object and hence the output will show a message that the input cannot be converted into an integer.
2.We can also use isdigit() method to check whether the input consists of only digits or not. The isdigit() method takes a string as input and returns True if the input string passed to it as an argument consists only of digital in the decimal system . Otherwise, it returns False. After checking if the input string consists of only digits or not, we can convert the input into integers.
In this example, we have used isdigit() method to check whether the given input string consists of only the digits or not. As the input string ”123” consists only of digits, the isdigit() function will return True and the input will be converted into an integer using the int() function as shown in the output.
If the input string contains any other character apart from digits, the isdigit() function will return False. Hence the input string will not be converted into an integer.
In this example, the given input is “123a” which contains an alphabet due to which isdigit() function will return False and the message will be displayed in the output that the input cannot be converted into integer as shown below.
3.It may be possible that the input string contains a floating point number and has a period character “.” between the digits. To convert such inputs to integers using the int() function, first we will check if the input string contains a floating point number i.e. it has only one period character between the digits or not using regular expressions. If yes, we will first convert the input into a floating point number which can be passed to int() function and then we will show the output. Otherwise, it will be notified that the input cannot be converted to an integer.
In this example, “^\d+\.\d$” denotes a pattern which starts with one or more digits, has a period symbol ”.” in the middle and ends with one or more digits which is the pattern for floating point numbers. Hence, if the input string is a floating point number, the re.search() method will not return None and the input will be converted into a floating point number using float() function and then it will be converted to an integer as follows.
If the input is not a floating point literal, the re.search() method will return a None object and the message will be shown in the output that input is not a floating point literal as follows.
For the two approaches using regular expressions, we can write a single program using groupdict() method after writing named patterns using re.match() object. groupdict() will return a python dictionary of named captured groups in the input and thus can be used to identify the string which can be converted to integer.
4.We can also use exception handling in python using python try except to handle the ValueError whenever the error occurs. In the try block of the code, we will normally execute the code. Whenever ValueError occurs, it will be raised in the try block and will be handled by the except block and a proper message will be shown to the user.
If the input consists of only the digits and is in correct format, output will be as follows.
If the input contains characters other than digits such as alphabets or punctuation, ValueError will be thrown from the int() function which will be caught by the except block and a message will be shown to the user that the input cannot be converted into integer.
Conclusion
In this article, we have seen why “ValueError: invalid literal for int() with base 10” occurs in python and have understood the reasons and mechanism behind it. We have also seen that this error can be avoided by first checking if the input to int() function consists of only digits or not using different methods like regular expressions and inbuilt functions.
ValueError: invalid literal for int() with base 10
ValueError occurs when we pass an invalid argument type. The error is raised when we call int() function with string argument which Python cannot parse and throws ValueError: invalid literal for int() with base 10: ”
Fix ValueError: invalid literal for int() with base 10
Let’s look at some examples and the solution to fix the ValueError in Python.
Example – Converting float to integer
If you look at the below example, we are trying to convert the input value into an integer that means we expect that the input field weight is always an integer value.
However, the user can enter weight even in decimal value, and when we try to convert it into an integer, Python throws invalid literal for int() with base 10 error.
One can think that while executing the above code, Python will automatically truncate the decimal value and retain only the integer part. The int() function uses the decimal number system as base conversion, meaning base=10 is the default value for transformation. Therefore it can only convert the string representation of int, not the decimal or float or chars.
Solution 1: We can first convert the input number into a float using float() method, parse the decimal digits, and convert them again into an integer, as shown below.
Solution 2: There can be other possible issues where the entered input value itself might be in the string, so converting the string value will throw a Value Error even if we use the above method.
So better way to solve this is to ensure the entered input is a numeric digit or not. Python has isdigit() method, which returns true in case of a numeric value and false if it’s non-numeric.
Solution 3: The other common way to handle this kind of errors is using try except
Conclusion
ValueError: invalid literal for int() with base 10 occurs when you convert the string or decimal or characters values not formatted as an integer.
To solve the error, you can use the float() method to convert entered decimal input and then use the int() method to convert your number to an integer. Alternatively, you can use the isdigit() method to check if the entered number is a digit or not, and the final way is to use try/except to handle the unknown errors.
How to Solve Python ValueError: invalid literal for int() with base 10 Solution
Invalid literal for int() with base 10 occurs when you try to convert an invalid object into an integer. Python is good at converting between different data types. When using the int() function, we must follow a specific set of rules. If we do not follow these rules, we will raise a ValueError There are two causes of this particular ValueError:
- If we pass a string containing anything that is not a number, this includes letters and special characters.
- If we pass a string-type object to int() that looks like a float type.
To solve or avoid the error, ensure that you do not pass int() any letters or special characters.
This tutorial will go through the error in detail and how to solve it with examples.
Table of contents
What is a ValueError?
In Python, a value is the information stored within a certain object. You will encounter a ValueError in Python when you use a built-in operation or function that receives an argument that has the right type but an inappropriate value. Let’s look at an example of converting several a ValueError:
The above code throws the ValueError because the value ‘ string ‘ is an inappropriate (non-convertible) string. You can only convert numerical strings using the float() method, for example:
The code does not throw an error because the float function can convert a numerical string. The value of 5 is appropriate for the float function.
Passing Non-numerical Arguments to int()
If we pass an argument to int() that contains letters or special characters, we will raise the invalid literal ValueError.
An integer is a whole number, so the argument provided should only have real numbers.
Let’s take the example of a program that takes an input and performs a calculation on the input.
In this example, the program interprets the two inputs as string-type and concatenates them to give “46”. However, we want the program to interpret the two inputs as integer-type to calculate the sum. We need to convert the values to integers before performing the sum as follows:
The code successfully runs, but the ValueError may still occur if the user inputs a value that is not an integer. Let’s look at an example, with the input “science”:
The ValueError tells us that “science” is not a number. We can solve this by putting the code in a try/except block to handle the error.
The code has an exception handler that will tell the user that the input values are not whole numbers.
Passing Float-like Strings to int()
If you pass a string-type object that looks like a float type, such as 5.3, you will also raise the ValueError. In this case, Python detects the “.” as a special character. We cannot pass strings or special characters to the int() function.
Let’s look at a bakery with a program to calculate whether it has enough cakes in stock to serve customers for the day. The input field must accept decimal numbers because cakes can be half consumed, quarter consumed, etc. We are only interested in integer level precision, not half cakes or quarter cakes, so we convert the input to an integer. We can use an if statement to check whether the bakery has more than a specified number of cakes. If there are not enough cakes, the program will inform us through a print statement. Otherwise, it will print that the bakery has enough cakes for the day. The program can look as follows:
Let’s run the code with an input of “5.4” as a string.
The ValueError occurs because we try to convert “5.4”, a string, as an integer. Python cannot convert a floating-point number in a string to an integer. To solve this issue, we need to convert the input to a floating-point number to convert to an integer. We can use the float() function, which returns a floating-point representation of a float, and the int() function produces an integer.
The code successfully runs, with the conversion of the input to a float, the program can convert it to an integer. Based on the output, the bakery has more baking to do!
Rounding Floats
Using the int() function works with floats. However, the function will truncate everything after the decimal without rounding to the nearest integer.
We can see 5.7 is closer to 6 than 5, but the int() function truncates regardless of the decimal value. If it is more suitable to round floats to the nearest integer, you can use the round() function. We can make the change to the code as follows:
The second argument of the round() function specifies how many decimal places we want. We want to round to zero decimal places or the nearest integer in this example.
Summary
Congratulations on completing this tutorial! You know how the ValueError: invalid literal int() base 10 occurs and how to solve it like an expert. To summarize, integers are whole numbers, so string-type objects passed to the int() function should only contain positive or negative numbers. If we want to give a string-type object that looks like a float, int() will raise the ValueError due to the presence of the “.” special character. You must convert float-like strings to a floating-point object first and then convert to an integer. You can use the round() function to ensure the int() function does not incorrectly truncate a number and specify the number of decimal places.
Generally, ValueError occurs when the value or values used in the code do not match what the Python interpreter expects. Another common ValueError is ValueError: too many values to unpack (expected 2)
You can find other solutions to Python TypeErrors, such as TypeError: can only concatenate str (not “int”) to str, SyntaxError: unexpected EOF while parsing, and TypeError: list indices must be integers or slices, not str. If you want to learn how to write Python programs specific to data science and machine learning, I provide a compilation of the best online courses on Python for data science and machine learning.