[SOLVED] Local Variable Referenced Before Assignment
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Python treats variables referenced only inside a function as global variables. Any variable assigned to a function’s body is assumed to be a local variable unless explicitly declared as global.
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Why Does This Error Occur?
Unboundlocalerror: local variable referenced before assignment occurs when a variable is used before its created. Python does not have the concept of variable declarations. Hence it searches for the variable whenever used. When not found, it throws the error.
Before we hop into the solutions, let’s have a look at what is the global and local variables.
Local Variable Declarations vs. Global Variable Declarations
Local Variables | Global Variables |
---|---|
A variable is declared primarily within a Python function. | Global variables are in the global scope, outside a function. |
A local variable is created when the function is called and destroyed when the execution is finished. | A Variable is created upon execution and exists in memory till the program stops. |
Local Variables can only be accessed within their own function. | All functions of the program can access global variables. |
Local variables are immune to changes in the global scope. Thereby being more secure. | Global Variables are less safer from manipulation as they are accessible in the global scope. |
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Local Variable Referenced Before Assignment Error with Explanation
Try these examples yourself using our Online Compiler.
Let’s look at the following function:
![local variable 'result_set' referenced before assignment Local Variable Referenced Before Assignment Error](https://www.pythonpool.com/wp-content/uploads/2022/04/image.png)
Explanation
The variable myVar has been assigned a value twice. Once before the declaration of myFunction and within myFunction itself.
Using Global Variables
Passing the variable as global allows the function to recognize the variable outside the function.
Create Functions that Take in Parameters
Instead of initializing myVar as a global or local variable, it can be passed to the function as a parameter. This removes the need to create a variable in memory.
UnboundLocalError: local variable ‘DISTRO_NAME’
This error may occur when trying to launch the Anaconda Navigator in Linux Systems.
Upon launching Anaconda Navigator, the opening screen freezes and doesn’t proceed to load.
Try and update your Anaconda Navigator with the following command.
If solution one doesn’t work, you have to edit a file located at
After finding and opening the Python file, make the following changes:
In the function on line 159, simply add the line:
DISTRO_NAME = None
Save the file and re-launch Anaconda Navigator.
DJANGO – Local Variable Referenced Before Assignment [Form]
The program takes information from a form filled out by a user. Accordingly, an email is sent using the information.
Upon running you get the following error:
We have created a class myForm that creates instances of Django forms. It extracts the user’s name, email, and message to be sent.
A function GetContact is created to use the information from the Django form and produce an email. It takes one request parameter. Prior to sending the email, the function verifies the validity of the form. Upon True , .get() function is passed to fetch the name, email, and message. Finally, the email sent via the send_mail function
Why does the error occur?
We are initializing form under the if request.method == “POST” condition statement. Using the GET request, our variable form doesn’t get defined.
Local variable Referenced before assignment but it is global
This is a common error that happens when we don’t provide a value to a variable and reference it. This can happen with local variables. Global variables can’t be assigned.
This error message is raised when a variable is referenced before it has been assigned a value within the local scope of a function, even though it is a global variable.
Here’s an example to help illustrate the problem:
In this example, x is a global variable that is defined outside of the function my_func(). However, when we try to print the value of x inside the function, we get a UnboundLocalError with the message “local variable ‘x’ referenced before assignment”.
This is because the += operator implicitly creates a local variable within the function’s scope, which shadows the global variable of the same name. Since we’re trying to access the value of x before it’s been assigned a value within the local scope, the interpreter raises an error.
To fix this, you can use the global keyword to explicitly refer to the global variable within the function’s scope:
However, in the above example, the global keyword tells Python that we want to modify the value of the global variable x, rather than creating a new local variable. This allows us to access and modify the global variable within the function’s scope, without causing any errors.
Local variable ‘version’ referenced before assignment ubuntu-drivers
This error occurs with Ubuntu version drivers. To solve this error, you can re-specify the version information and give a split as 2 –
Here, p_name means package name.
With the help of the threading module, you can avoid using global variables in multi-threading. Make sure you lock and release your threads correctly to avoid the race condition.
When a variable that is created locally is called before assigning, it results in Unbound Local Error in Python. The interpreter can’t track the variable.
Therefore, we have examined the local variable referenced before the assignment Exception in Python. The differences between a local and global variable declaration have been explained, and multiple solutions regarding the issue have been provided.
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Fix "local variable referenced before assignment" in Python
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Introduction
If you're a Python developer, you've probably come across a variety of errors, like the "local variable referenced before assignment" error. This error can be a bit puzzling, especially for beginners and when it involves local/global variables.
Today, we'll explain this error, understand why it occurs, and see how you can fix it.
The "local variable referenced before assignment" Error
The "local variable referenced before assignment" error in Python is a common error that occurs when a local variable is referenced before it has been assigned a value. This error is a type of UnboundLocalError , which is raised when a local variable is referenced before it has been assigned in the local scope.
Here's a simple example:
Running this code will throw the "local variable 'x' referenced before assignment" error. This is because the variable x is referenced in the print(x) statement before it is assigned a value in the local scope of the foo function.
Even more confusing is when it involves global variables. For example, the following code also produces the error:
But wait, why does this also produce the error? Isn't x assigned before it's used in the say_hello function? The problem here is that x is a global variable when assigned "Hello ". However, in the say_hello function, it's a different local variable, which has not yet been assigned.
We'll see later in this Byte how you can fix these cases as well.
Fixing the Error: Initialization
One way to fix this error is to initialize the variable before using it. This ensures that the variable exists in the local scope before it is referenced.
Let's correct the error from our first example:
In this revised code, we initialize x with a value of 1 before printing it. Now, when you run the function, it will print 1 without any errors.
Fixing the Error: Global Keyword
Another way to fix this error, depending on your specific scenario, is by using the global keyword. This is especially useful when you want to use a global variable inside a function.
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Here's how:
In this snippet, we declare x as a global variable inside the function foo . This tells Python to look for x in the global scope, not the local one . Now, when you run the function, it will increment the global x by 1 and print 1 .
Similar Error: NameError
An error that's similar to the "local variable referenced before assignment" error is the NameError . This is raised when you try to use a variable or a function name that has not been defined yet.
Running this code will result in a NameError :
In this case, we're trying to print the value of y , but y has not been defined anywhere in the code. Hence, Python raises a NameError . This is similar in that we are trying to use an uninitialized/undefined variable, but the main difference is that we didn't try to initialize y anywhere else in our code.
Variable Scope in Python
Understanding the concept of variable scope can help avoid many common errors in Python, including the main error of interest in this Byte. But what exactly is variable scope?
In Python, variables have two types of scope - global and local. A variable declared inside a function is known as a local variable, while a variable declared outside a function is a global variable.
Consider this example:
In this code, x is a global variable, and y is a local variable. x can be accessed anywhere in the code, but y can only be accessed within my_function . Confusion surrounding this is one of the most common causes for the "variable referenced before assignment" error.
In this Byte, we've taken a look at the "local variable referenced before assignment" error and another similar error, NameError . We also delved into the concept of variable scope in Python, which is an important concept to understand to avoid these errors. If you're seeing one of these errors, check the scope of your variables and make sure they're being assigned before they're being used.
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Local variable referenced before assignment in Python
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Last updated: Apr 8, 2024 Reading time · 4 min
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# Local variable referenced before assignment in Python
The Python "UnboundLocalError: Local variable referenced before assignment" occurs when we reference a local variable before assigning a value to it in a function.
To solve the error, mark the variable as global in the function definition, e.g. global my_var .
![local variable 'result_set' referenced before assignment unboundlocalerror local variable name referenced before assignment](https://bobbyhadz.com/images/blog/python-unboundlocalerror-local-variable-name-referenced-before-assignment/unboundlocalerror-local-variable-name-referenced-before-assignment.webp)
Here is an example of how the error occurs.
We assign a value to the name variable in the function.
# Mark the variable as global to solve the error
To solve the error, mark the variable as global in your function definition.
![local variable 'result_set' referenced before assignment mark variable as global](https://bobbyhadz.com/images/blog/python-unboundlocalerror-local-variable-name-referenced-before-assignment/mark-variable-as-global.webp)
If a variable is assigned a value in a function's body, it is a local variable unless explicitly declared as global .
# Local variables shadow global ones with the same name
You could reference the global name variable from inside the function but if you assign a value to the variable in the function's body, the local variable shadows the global one.
![local variable 'result_set' referenced before assignment accessing global variables in functions](https://bobbyhadz.com/images/blog/python-unboundlocalerror-local-variable-name-referenced-before-assignment/accessing-global-variables-in-functions.webp)
Accessing the name variable in the function is perfectly fine.
On the other hand, variables declared in a function cannot be accessed from the global scope.
![local variable 'result_set' referenced before assignment variables declared in function cannot be accessed in global scope](https://bobbyhadz.com/images/blog/python-unboundlocalerror-local-variable-name-referenced-before-assignment/variables-declared-in-function-cannot-be-accessed-in-global-scope.webp)
The name variable is declared in the function, so trying to access it from outside causes an error.
Make sure you don't try to access the variable before using the global keyword, otherwise, you'd get the SyntaxError: name 'X' is used prior to global declaration error.
# Returning a value from the function instead
An alternative solution to using the global keyword is to return a value from the function and use the value to reassign the global variable.
![local variable 'result_set' referenced before assignment return value from the function](https://bobbyhadz.com/images/blog/python-unboundlocalerror-local-variable-name-referenced-before-assignment/return-value-from-the-function.webp)
We simply return the value that we eventually use to assign to the name global variable.
# Passing the global variable as an argument to the function
You should also consider passing the global variable as an argument to the function.
![local variable 'result_set' referenced before assignment pass global variable as argument to function](https://bobbyhadz.com/images/blog/python-unboundlocalerror-local-variable-name-referenced-before-assignment/pass-global-variable-as-argument-to-function.webp)
We passed the name global variable as an argument to the function.
If we assign a value to a variable in a function, the variable is assumed to be local unless explicitly declared as global .
# Assigning a value to a local variable from an outer scope
If you have a nested function and are trying to assign a value to the local variables from the outer function, use the nonlocal keyword.
![local variable 'result_set' referenced before assignment assign value to local variable from outer scope](https://bobbyhadz.com/images/blog/python-unboundlocalerror-local-variable-name-referenced-before-assignment/assign-value-to-local-variable-from-outer-scope.webp)
The nonlocal keyword allows us to work with the local variables of enclosing functions.
Had we not used the nonlocal statement, the call to the print() function would have returned an empty string.
![local variable 'result_set' referenced before assignment not using nonlocal prints empty string](https://bobbyhadz.com/images/blog/python-unboundlocalerror-local-variable-name-referenced-before-assignment/not-using-nonlocal-prints-empty-string.webp)
Printing the message variable on the last line of the function shows an empty string because the inner() function has its own scope.
Changing the value of the variable in the inner scope is not possible unless we use the nonlocal keyword.
Instead, the message variable in the inner function simply shadows the variable with the same name from the outer scope.
# Discussion
As shown in this section of the documentation, when you assign a value to a variable inside a function, the variable:
- Becomes local to the scope.
- Shadows any variables from the outer scope that have the same name.
The last line in the example function assigns a value to the name variable, marking it as a local variable and shadowing the name variable from the outer scope.
At the time the print(name) line runs, the name variable is not yet initialized, which causes the error.
The most intuitive way to solve the error is to use the global keyword.
The global keyword is used to indicate to Python that we are actually modifying the value of the name variable from the outer scope.
- If a variable is only referenced inside a function, it is implicitly global.
- If a variable is assigned a value inside a function's body, it is assumed to be local, unless explicitly marked as global .
If you want to read more about why this error occurs, check out [this section] ( this section ) of the docs.
# Additional Resources
You can learn more about the related topics by checking out the following tutorials:
- SyntaxError: name 'X' is used prior to global declaration
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How to fix UnboundLocalError: local variable 'x' referenced before assignment in Python
You could also see this error when you forget to pass the variable as an argument to your function.
How to reproduce this error
How to fix this error.
I hope this tutorial is useful. See you in other tutorials.
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Python local variable referenced before assignment Solution
When you start introducing functions into your code, you’re bound to encounter an UnboundLocalError at some point. This error is raised when you try to use a variable before it has been assigned in the local context .
In this guide, we talk about what this error means and why it is raised. We walk through an example of this error in action to help you understand how you can solve it.
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What is unboundlocalerror: local variable referenced before assignment.
Trying to assign a value to a variable that does not have local scope can result in this error:
Python has a simple rule to determine the scope of a variable. If a variable is assigned in a function , that variable is local. This is because it is assumed that when you define a variable inside a function you only need to access it inside that function.
There are two variable scopes in Python: local and global. Global variables are accessible throughout an entire program; local variables are only accessible within the function in which they are originally defined.
Let’s take a look at how to solve this error.
An Example Scenario
We’re going to write a program that calculates the grade a student has earned in class.
We start by declaring two variables:
These variables store the numerical and letter grades a student has earned, respectively. By default, the value of “letter” is “F”. Next, we write a function that calculates a student’s letter grade based on their numerical grade using an “if” statement :
Finally, we call our function:
This line of code prints out the value returned by the calculate_grade() function to the console. We pass through one parameter into our function: numerical. This is the numerical value of the grade a student has earned.
Let’s run our code and see what happens:
An error has been raised.
The Solution
Our code returns an error because we reference “letter” before we assign it.
We have set the value of “numerical” to 42. Our if statement does not set a value for any grade over 50. This means that when we call our calculate_grade() function, our return statement does not know the value to which we are referring.
We do define “letter” at the start of our program. However, we define it in the global context. Python treats “return letter” as trying to return a local variable called “letter”, not a global variable.
We solve this problem in two ways. First, we can add an else statement to our code. This ensures we declare “letter” before we try to return it:
Let’s try to run our code again:
Our code successfully prints out the student’s grade.
If you are using an “if” statement where you declare a variable, you should make sure there is an “else” statement in place. This will make sure that even if none of your if statements evaluate to True, you can still set a value for the variable with which you are going to work.
Alternatively, we could use the “global” keyword to make our global keyword available in the local context in our calculate_grade() function. However, this approach is likely to lead to more confusing code and other issues. In general, variables should not be declared using “global” unless absolutely necessary . Your first, and main, port of call should always be to make sure that a variable is correctly defined.
In the example above, for instance, we did not check that the variable “letter” was defined in all use cases.
That’s it! We have fixed the local variable error in our code.
The UnboundLocalError: local variable referenced before assignment error is raised when you try to assign a value to a local variable before it has been declared. You can solve this error by ensuring that a local variable is declared before you assign it a value.
Now you’re ready to solve UnboundLocalError Python errors like a professional developer !
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How to Fix Local Variable Referenced Before Assignment Error in Python
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Table of Contents
Fixing local variable referenced before assignment error.
In Python , when you try to reference a variable that hasn't yet been given a value (assigned), it will throw an error.
That error will look like this:
In this post, we'll see examples of what causes this and how to fix it.
Let's begin by looking at an example of this error:
If you run this code, you'll get
The issue is that in this line:
We are defining a local variable called value and then trying to use it before it has been assigned a value, instead of using the variable that we defined in the first line.
If we want to refer the variable that was defined in the first line, we can make use of the global keyword.
The global keyword is used to refer to a variable that is defined outside of a function.
Let's look at how using global can fix our issue here:
Global variables have global scope, so you can referenced them anywhere in your code, thus avoiding the error.
If you run this code, you'll get this output:
In this post, we learned at how to avoid the local variable referenced before assignment error in Python.
The error stems from trying to refer to a variable without an assigned value, so either make use of a global variable using the global keyword, or assign the variable a value before using it.
Thanks for reading!
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4 ways to fix local variable referenced before assignment error in python, resolving the local variable referenced before assignment error in python.
Python is one of the world’s most popular programming languages due to its simplicity, readability, and versatility. Despite its many advantages, when coding in Python, one may encounter various errors, with the most common being the “local variable referenced before assignment” error.
Even the most experienced Python developers have encountered this error at some point in their programming career. In this article, we will look at four effective strategies for resolving the local variable referenced before assignment error in Python.
Strategy 1: Assigning a Value before Referencing
The first strategy is to assign a value to a variable before referencing it. The error occurs when the variable is referenced before it is assigned a value.
This problem can be avoided by initializing the variable before referencing it. For example, let us consider the snippet below:
In the snippet above, the variables x and y are not assigned values before they are referenced in the print statement. Therefore, we will get a local variable “referenced before assignment” error.
To resolve this error, we must initialize the variables before referencing them. We can avoid this error by assigning a value to x and y before they are referenced, as shown below:
Strategy 2: Using the Global Keyword
In Python, variables declared inside a function are considered local variables. Thus, they are separate from other variables declared outside of the function.
If we want to use a variable outside of the function, we must use the global keyword. Using the global keyword tells Python that you want to use the variable that was defined globally, not locally.
For example:
In the code snippet above, the global keyword tells Python to use the variable x defined outside of the function rather than a local variable named x . Thus, Python will output 30.
Strategy 3: Adding Input Parameters for Functions
Another way to avoid the local variable referenced before assignment error is by adding input parameters to functions.
In the code snippet above, x and y are variables that are passed into the add_numbers function as arguments.
This approach allows us to avoid the local variable referenced before assignment error because the variables are being passed into the function as input parameters.
Strategy 4: Initializing Variables before Loops or Conditionals
Finally, it’s also a good practice to initialize the variables before loops or conditionals.
If you are defining a variable within a loop, you must initialize it before the loop starts. This way, the variable already exists, and we can update the value inside the loop.
In the code snippet above, the variable sum has been initialized with the value of 0 before the loop runs. Thus, we can update and use the variable inside the loop.
In conclusion, the “local variable referenced before assignment” error is a common issue in Python. However, with the strategies discussed in this article, you can avoid the error and write clean Python code.
Remember to initialize your variables, use the global keyword, add input parameters in functions, and initialize variables before loops or conditionals. By following these techniques, your Python code will be error-free and much easier to manage.
In essence, this article has provided four key strategies for resolving the “local variable referenced before assignment” error that is common in Python. These strategies include initializing variables before referencing, using the global keyword, adding input parameters to functions, and initializing variables before loops or conditionals.
These techniques help to ensure clean code that is free from errors. By implementing these strategies, developers can improve their code quality and avoid time-wasting errors that can occur in their work.
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Check the Variable Scope to Fix the local variable referenced before assignment Error in Python
Initialize the variable before use to fix the local variable referenced before assignment error in python, use conditional assignment to fix the local variable referenced before assignment error in python.
![local variable 'result_set' referenced before assignment How to Solve Error - Local Variable Referenced Before Assignment in Python](https://www.delftstack.com/img/Python/feature-image---python-local-variable-referenced-before-assignment.webp)
This article delves into various strategies to resolve the common local variable referenced before assignment error. By exploring methods such as checking variable scope, initializing variables before use, conditional assignments, and more, we aim to equip both novice and seasoned programmers with practical solutions.
Each method is dissected with examples, demonstrating how subtle changes in code can prevent this frequent error, enhancing the robustness and readability of your Python projects.
The local variable referenced before assignment occurs when some variable is referenced before assignment within a function’s body. The error usually occurs when the code is trying to access the global variable.
The primary purpose of managing variable scope is to ensure that variables are accessible where they are needed while maintaining code modularity and preventing unexpected modifications to global variables.
We can declare the variable as global using the global keyword in Python. Once the variable is declared global, the program can access the variable within a function, and no error will occur.
The below example code demonstrates the code scenario where the program will end up with the local variable referenced before assignment error.
In this example, my_var is a global variable. Inside update_var , we attempt to modify it without declaring its scope, leading to the Local Variable Referenced Before Assignment error.
We need to declare the my_var variable as global using the global keyword to resolve this error. The below example code demonstrates how the error can be resolved using the global keyword in the above code scenario.
In the corrected code, we use the global keyword to inform Python that my_var references the global variable.
When we first print my_var , it displays the original value from the global scope.
After assigning a new value to my_var , it updates the global variable, not a local one. This way, we effectively tell Python the scope of our variable, thus avoiding any conflicts between local and global variables with the same name.
![local variable 'result_set' referenced before assignment python local variable referenced before assignment - output 1](https://www.delftstack.com/img/Python/python-local-variable-referenced-before-assignment---output-1.webp)
Ensure that the variable is initialized with some value before using it. This can be done by assigning a default value to the variable at the beginning of the function or code block.
The main purpose of initializing variables before use is to ensure that they have a defined state before any operations are performed on them. This practice is not only crucial for avoiding the aforementioned error but also promotes writing clear and predictable code, which is essential in both simple scripts and complex applications.
In this example, the variable total is used in the function calculate_total without prior initialization, leading to the Local Variable Referenced Before Assignment error. The below example code demonstrates how the error can be resolved in the above code scenario.
In our corrected code, we initialize the variable total with 0 before using it in the loop. This ensures that when we start adding item values to total , it already has a defined state (in this case, 0).
This initialization is crucial because it provides a starting point for accumulation within the loop. Without this step, Python does not know the initial state of total , leading to the error.
![local variable 'result_set' referenced before assignment python local variable referenced before assignment - output 2](https://www.delftstack.com/img/Python/python-local-variable-referenced-before-assignment---output-2.webp)
Conditional assignment allows variables to be assigned values based on certain conditions or logical expressions. This method is particularly useful when a variable’s value depends on certain prerequisites or states, ensuring that a variable is always initialized before it’s used, thereby avoiding the common error.
In this example, message is only assigned within the if and elif blocks. If neither condition is met (as with guest ), the variable message remains uninitialized, leading to the Local Variable Referenced Before Assignment error when trying to print it.
The below example code demonstrates how the error can be resolved in the above code scenario.
In the revised code, we’ve included an else statement as part of our conditional logic. This guarantees that no matter what value user_type holds, the variable message will be assigned some value before it is used in the print function.
This conditional assignment ensures that the message is always initialized, thereby eliminating the possibility of encountering the Local Variable Referenced Before Assignment error.
![local variable 'result_set' referenced before assignment python local variable referenced before assignment - output 3](https://www.delftstack.com/img/Python/python-local-variable-referenced-before-assignment---output-3.webp)
Throughout this article, we have explored multiple approaches to address the Local Variable Referenced Before Assignment error in Python. From the nuances of variable scope to the effectiveness of initializations and conditional assignments, these strategies are instrumental in developing error-free code.
The key takeaway is the importance of understanding variable scope and initialization in Python. By applying these methods appropriately, programmers can not only resolve this specific error but also enhance the overall quality and maintainability of their code, making their programming journey smoother and more rewarding.
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UnboundLocalError Local variable Referenced Before Assignment in Python
Handling errors is an integral part of writing robust and reliable Python code. One common stumbling block that developers often encounter is the “UnboundLocalError” raised within a try-except block. This error can be perplexing for those unfamiliar with its nuances but fear not – in this article, we will delve into the intricacies of the UnboundLocalError and provide a comprehensive guide on how to effectively use try-except statements to resolve it.
What is UnboundLocalError Local variable Referenced Before Assignment in Python?
The UnboundLocalError occurs when a local variable is referenced before it has been assigned a value within a function or method. This error typically surfaces when utilizing try-except blocks to handle exceptions, creating a puzzle for developers trying to comprehend its origins and find a solution.
Why does UnboundLocalError: Local variable Referenced Before Assignment Occur?
below, are the reasons of occurring “Unboundlocalerror: Try Except Statements” in Python :
Variable Assignment Inside Try Block
Reassigning a global variable inside except block.
- Accessing a Variable Defined Inside an If Block
In the below code, example_function attempts to execute some_operation within a try-except block. If an exception occurs, it prints an error message. However, if no exception occurs, it prints the value of the variable result outside the try block, leading to an UnboundLocalError since result might not be defined if an exception was caught.
In below code , modify_global function attempts to increment the global variable global_var within a try block, but it raises an UnboundLocalError. This error occurs because the function treats global_var as a local variable due to the assignment operation within the try block.
Solution for UnboundLocalError Local variable Referenced Before Assignment
Below, are the approaches to solve “Unboundlocalerror: Try Except Statements”.
Initialize Variables Outside the Try Block
Avoid reassignment of global variables.
In modification to the example_function is correct. Initializing the variable result before the try block ensures that it exists even if an exception occurs within the try block. This helps prevent UnboundLocalError when trying to access result in the print statement outside the try block.
Below, code calculates a new value ( local_var ) based on the global variable and then prints both the local and global variables separately. It demonstrates that the global variable is accessed directly without being reassigned within the function.
In conclusion , To fix “UnboundLocalError” related to try-except statements, ensure that variables used within the try block are initialized before the try block starts. This can be achieved by declaring the variables with default values or assigning them None outside the try block. Additionally, when modifying global variables within a try block, use the `global` keyword to explicitly declare them.
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Python UnboundLocalError: local variable referenced before assignment
by Suf | Programming , Python , Tips
If you try to reference a local variable before assigning a value to it within the body of a function, you will encounter the UnboundLocalError: local variable referenced before assignment.
The preferable way to solve this error is to pass parameters to your function, for example:
Alternatively, you can declare the variable as global to access it while inside a function. For example,
This tutorial will go through the error in detail and how to solve it with code examples .
Table of contents
What is scope in python, unboundlocalerror: local variable referenced before assignment, solution #1: passing parameters to the function, solution #2: use global keyword, solution #1: include else statement, solution #2: use global keyword.
Scope refers to a variable being only available inside the region where it was created. A variable created inside a function belongs to the local scope of that function, and we can only use that variable inside that function.
A variable created in the main body of the Python code is a global variable and belongs to the global scope. Global variables are available within any scope, global and local.
UnboundLocalError occurs when we try to modify a variable defined as local before creating it. If we only need to read a variable within a function, we can do so without using the global keyword. Consider the following example that demonstrates a variable var created with global scope and accessed from test_func :
If we try to assign a value to var within test_func , the Python interpreter will raise the UnboundLocalError:
This error occurs because when we make an assignment to a variable in a scope, that variable becomes local to that scope and overrides any variable with the same name in the global or outer scope.
var +=1 is similar to var = var + 1 , therefore the Python interpreter should first read var , perform the addition and assign the value back to var .
var is a variable local to test_func , so the variable is read or referenced before we have assigned it. As a result, the Python interpreter raises the UnboundLocalError.
Example #1: Accessing a Local Variable
Let’s look at an example where we define a global variable number. We will use the increment_func to increase the numerical value of number by 1.
Let’s run the code to see what happens:
The error occurs because we tried to read a local variable before assigning a value to it.
We can solve this error by passing a parameter to increment_func . This solution is the preferred approach. Typically Python developers avoid declaring global variables unless they are necessary. Let’s look at the revised code:
We have assigned a value to number and passed it to the increment_func , which will resolve the UnboundLocalError. Let’s run the code to see the result:
We successfully printed the value to the console.
We also can solve this error by using the global keyword. The global statement tells the Python interpreter that inside increment_func , the variable number is a global variable even if we assign to it in increment_func . Let’s look at the revised code:
Let’s run the code to see the result:
Example #2: Function with if-elif statements
Let’s look at an example where we collect a score from a player of a game to rank their level of expertise. The variable we will use is called score and the calculate_level function takes in score as a parameter and returns a string containing the player’s level .
In the above code, we have a series of if-elif statements for assigning a string to the level variable. Let’s run the code to see what happens:
The error occurs because we input a score equal to 40 . The conditional statements in the function do not account for a value below 55 , therefore when we call the calculate_level function, Python will attempt to return level without any value assigned to it.
We can solve this error by completing the set of conditions with an else statement. The else statement will provide an assignment to level for all scores lower than 55 . Let’s look at the revised code:
In the above code, all scores below 55 are given the beginner level. Let’s run the code to see what happens:
We can also create a global variable level and then use the global keyword inside calculate_level . Using the global keyword will ensure that the variable is available in the local scope of the calculate_level function. Let’s look at the revised code.
In the above code, we put the global statement inside the function and at the beginning. Note that the “default” value of level is beginner and we do not include the else statement in the function. Let’s run the code to see the result:
Congratulations on reading to the end of this tutorial! The UnboundLocalError: local variable referenced before assignment occurs when you try to reference a local variable before assigning a value to it. Preferably, you can solve this error by passing parameters to your function. Alternatively, you can use the global keyword.
If you have if-elif statements in your code where you assign a value to a local variable and do not account for all outcomes, you may encounter this error. In which case, you must include an else statement to account for the missing outcome.
For further reading on Python code blocks and structure, go to the article: How to Solve Python IndentationError: unindent does not match any outer indentation level .
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Weird set() error. local variable 'set' referenced before assignment
I'm trying to use set() :
However, I get this error:
![local variable 'result_set' referenced before assignment Ashwini Chaudhary's user avatar](https://i.sstatic.net/E9dZn.png?s=64)
- I can't believe that I didn't see it – Anton Commented Sep 25, 2013 at 16:54
Don't use built-in functions as variables names, this is causing that error:
Docs: Why am I getting an UnboundLocalError when the variable has a value?
- 2 Since you assign to set in the function (a for loop is an implicit assignment), set is a local variable that shadows the built-in type set . It hasn't been assigned at the time you try to use set() to create a set, which is why you get the error about referencing it before its assignment. – kindall Commented Sep 25, 2013 at 16:53
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local variable referenced before assignment error
Hello colleagues,
I am solving a binary tree problem using recursive approach as shown below. My goal is to define variable cnt as global for the inner function check . Therefore, it has been defined outside the scope of check `
But I am getting following error;
UnboundLocalError: local variable 'cnt' referenced before assignment
I am failing to understand how cnt can be local variable for the inner function. Advice is appreciated.
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File "weird.py", line 5, in main. print f(3) UnboundLocalError: local variable 'f' referenced before assignment. Python sees the f is used as a local variable in [f for f in [1, 2, 3]], and decides that it is also a local variable in f(3). You could add a global f statement: def f(x): return x. def main():
Local Variables Global Variables; A local variable is declared primarily within a Python function.: Global variables are in the global scope, outside a function. A local variable is created when the function is called and destroyed when the execution is finished.
Output. Hangup (SIGHUP) Traceback (most recent call last): File "Solution.py", line 7, in <module> example_function() File "Solution.py", line 4, in example_function x += 1 # Trying to modify global variable 'x' without declaring it as global UnboundLocalError: local variable 'x' referenced before assignment Solution for Local variable Referenced Before Assignment in Python
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If a variable is assigned a value in a function's body, it is a local variable unless explicitly declared as global. # Local variables shadow global ones with the same name You could reference the global name variable from inside the function but if you assign a value to the variable in the function's body, the local variable shadows the global one.
The UnboundLocalError: local variable 'x' referenced before assignment occurs when you reference a variable inside a function before declaring that variable. To resolve this error, you need to use a different variable name when referencing the existing variable, or you can also specify a parameter for the function. I hope this tutorial is useful.
Trying to assign a value to a variable that does not have local scope can result in this error: UnboundLocalError: local variable referenced before assignment. Python has a simple rule to determine the scope of a variable. If a variable is assigned in a function, that variable is local. This is because it is assumed that when you define a ...
value = value + 1 print (value) increment() If you run this code, you'll get. BASH. UnboundLocalError: local variable 'value' referenced before assignment. The issue is that in this line: PYTHON. value = value + 1. We are defining a local variable called value and then trying to use it before it has been assigned a value, instead of using the ...
Strategy 2: Using the Global Keyword. In Python, variables declared inside a function are considered local variables. Thus, they are separate from other variables declared outside of the function.
This tutorial explains the reason and solution of the python error local variable referenced before assignment
UnboundLocalError: local variable 'result' referenced before assignment. To solve this, you should define result before the for loop with a default value. In addition, it sounds like the get_response function doesn't get the values you expect (i.e intents_list 's and\or intents_json 's content is different than what you are expecting).
Avoid Reassignment of Global Variables. Below, code calculates a new value (local_var) based on the global variable and then prints both the local and global variables separately.It demonstrates that the global variable is accessed directly without being reassigned within the function.
UnboundLocalError: local variable referenced before assignment. Example #1: Accessing a Local Variable. Solution #1: Passing Parameters to the Function. Solution #2: Use Global Keyword. Example #2: Function with if-elif statements. Solution #1: Include else statement. Solution #2: Use global keyword. Summary.
The Unboundlocalerror: local variable referenced before assignment is raised when you try to use a variable before it has been assigned in the local context. Python doesn't have variable declarations , so it has to figure out the scope of variables itself. It does so by a simple rule: If there is an assignment to a variable inside a function ...
Why? Because it's a local variable. Every time you enter that function it will set ticks to 0. So ticks will always be 0. Same with anything else you set inside the function. It looks to me like some of these things are part of the state of the sprite. So they should be attributes of the object, self.tick, etc.
This is a great explanation. This made me realize that variable binding (if that's the right word) actually happens at the time of the function definition, which is how you end up with attempts getting set as a local variable ahead of trying to evaluate attempts - 1. I thought (incorrectly) for some reason it was all handled at run time, and ...
cleanup() except Exception: pass. return result. There is a warning about Local variable 'result' might be referenced before assignment: But I can't really see how that's possible. One of these must be true: calculate() raises an exception --> the return statement will never get reached, so result is not referenced again. calculate() does not ...
In order for you to modify test1 while inside a function you will need to do define test1 as a global variable, for example: test1 = 0. def test_func(): global test1. test1 += 1. test_func() However, if you only need to read the global variable you can print it without using the keyword global, like so: test1 = 0.
Local variable referenced before assignment *RESOLVED. Thanks for u/Essence1337 and u/endeesa for the helpful advice! I'm trying to create a function that loops to asks for, validates, and returns a positive integer. ... object-oriented scripting language, and a set of tools for executing scripts/cmdlets and managing modules. Members Online ...
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UnboundLocalError: local variable 'cnt' referenced before assignment. I am failing to understand how cnt can be local variable for the inner function. Advice is appreciated. Related Topics ... Each function has its own set of names that refer to local vs. global variables, ...