Syntax error cannot assign to literal

Syntax error cannot assign to literal

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SyntaxError: cannot assign to literal here (Python) #

The Python «SyntaxError: cannot assign to literal here. Maybe you meant ‘==’ instead of ‘=’?» occurs when we try to assign to a literal (e.g. a string or a number). To solve the error, specify the variable name on the left and the value on the right-hand side of the assignment.

Here are 2 examples of how the error occurs.

When declaring a variable make sure the variable name is on the left-hand side and the value is on the right-hand side of the assignment ( = ).

Notice that variable names should be wrapped in quotes as that is a string literal.

The string «name» is always going to be equal to the string «name» , and the number 100 is always going to be equal to the number 100 , so we cannot assign a value to a literal.

You can think of a variable as a container that stores a specific value.

Variable names should not be wrapped in quotes.

If you got the error while declaring multiple variables on the same line, use the following syntax.

The variable names are still on the left, and the values are on the right-hand side.

If you meant to perform an equality comparison, use double equals.

We use double equals == for comparison and single equals = for assignment.

The name of a variable must start with a letter or an underscore.

A variable name can contain alpha-numeric characters ( a-z , A-Z , 0-9 ) and underscores _ .

Note that variable names cannot start with numbers or be wrapped in quotes.

Variable names in Python are case-sensitive.

The 2 variables in the example are completely different and are stored in different locations in memory.

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Python SyntaxError: can’t assign to literal Solution

Variables cannot be assigned to literal values like strings or numbers. If you try to assign a variable to a literal, you’ll encounter the “SyntaxError: can’t assign to literal” error.

This guide discusses what this error means and why you may encounter it. We’ll explore an example of how to fix this error so that you can build the knowledge you need to solve this error in your own code.

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SyntaxError: can’t assign to literal

A variable is a unique identifier for a value. When you reference a variable, Python will read the value associated with that variable. Python uses an equals sign to assign values to a variable:

“language” is the name of our variable. The equals sign tells Python we are assigning a value to the variable. “Python” is the value that is associated with our variable.

Variables are containers for values. They are not values in themselves. This means you cannot give a variable a name that is equal to a value. If variable names could be equal to a value, Python would not be able to distinguish variables from values.

Variables cannot be strings, booleans, or any other data type. They must be declared using the syntax that we discussed above.

An Example Scenario

We’re going to build a program that calculates a discount for a product in a donut store. To start, ask the user to insert a price of a donut:

Next, ask the user to choose the percentage discount that should be applied to the donut:

The input() method returns a string. We cannot run mathematical operations on a string so we need to convert the data we gather to a numerical value. We’ve converted both of these values to floats using the float() method.

Now that we have these two values, we can calculate the discounted price:

We calculate the discounted price using a percentage decrease formula. We round the discounted price to the nearest two decimal places. Then, we print out the discounted price to the console.

Let’s run the code:

We have run into an error.

The Solution

“price” is a literal value. It is a string. We have tried to assign a value to this literal. This causes an error because variable names must be identifiers, not values.

We can fix this error by removing the quotation marks around our first two variables:

Our variables now have unique identifiers. We can use the labels price and discount to identify these values. Let’s run our program:

Our code successfully calculates the discounted value of a product.

Conclusion

The “SyntaxError: can’t assign to literal” error occurs when you try to assign a value to a literal value such as a boolean, a string, a list, or a number. To solve this error, ensure your variable names are names rather than values.

Now you have the knowledge you need to fix this error like a professional!

About us: Career Karma is a platform designed to help job seekers find, research, and connect with job training programs to advance their careers. Learn about the CK publication.

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Invalid Syntax in Python: Common Reasons for SyntaxError

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Watch Now This tutorial has a related video course created by the Real Python team. Watch it together with the written tutorial to deepen your understanding: Identify Invalid Python Syntax

Python is known for its simple syntax. However, when you’re learning Python for the first time or when you’ve come to Python with a solid background in another programming language, you may run into some things that Python doesn’t allow. If you’ve ever received a SyntaxError when trying to run your Python code, then this guide can help you. Throughout this tutorial, you’ll see common examples of invalid syntax in Python and learn how to resolve the issue.

By the end of this tutorial, you’ll be able to:

• Identify invalid syntax in Python
• Make sense of SyntaxError tracebacks
• Resolve invalid syntax or prevent it altogether

Free Bonus: 5 Thoughts On Python Mastery, a free course for Python developers that shows you the roadmap and the mindset you’ll need to take your Python skills to the next level.

Invalid Syntax in Python

When you run your Python code, the interpreter will first parse it to convert it into Python byte code, which it will then execute. The interpreter will find any invalid syntax in Python during this first stage of program execution, also known as the parsing stage. If the interpreter can’t parse your Python code successfully, then this means that you used invalid syntax somewhere in your code. The interpreter will attempt to show you where that error occurred.

When you’re learning Python for the first time, it can be frustrating to get a SyntaxError . Python will attempt to help you determine where the invalid syntax is in your code, but the traceback it provides can be a little confusing. Sometimes, the code it points to is perfectly fine.

Note: If your code is syntactically correct, then you may get other exceptions raised that are not a SyntaxError . To learn more about Python’s other exceptions and how to handle them, check out Python Exceptions: An Introduction.

You can’t handle invalid syntax in Python like other exceptions. Even if you tried to wrap a try and except block around code with invalid syntax, you’d still see the interpreter raise a SyntaxError .

SyntaxError Exception and Traceback

When the interpreter encounters invalid syntax in Python code, it will raise a SyntaxError exception and provide a traceback with some helpful information to help you debug the error. Here’s some code that contains invalid syntax in Python:

You can see the invalid syntax in the dictionary literal on line 4. The second entry, ‘jim’ , is missing a comma. If you tried to run this code as-is, then you’d get the following traceback:

Note that the traceback message locates the error in line 5, not line 4. The Python interpreter is attempting to point out where the invalid syntax is. However, it can only really point to where it first noticed a problem. When you get a SyntaxError traceback and the code that the traceback is pointing to looks fine, then you’ll want to start moving backward through the code until you can determine what’s wrong.

In the example above, there isn’t a problem with leaving out a comma, depending on what comes after it. For example, there’s no problem with a missing comma after ‘michael’ in line 5. But once the interpreter encounters something that doesn’t make sense, it can only point you to the first thing it found that it couldn’t understand.

Note: This tutorial assumes that you know the basics of Python’s tracebacks. To learn more about the Python traceback and how to read them, check out Understanding the Python Traceback and Getting the Most out of a Python Traceback.

There are a few elements of a SyntaxError traceback that can help you determine where the invalid syntax is in your code:

• The file name where the invalid syntax was encountered
• The line number and reproduced line of code where the issue was encountered
• A caret ( ^ ) on the line below the reproduced code, which shows you the point in the code that has a problem
• The error message that comes after the exception type SyntaxError , which can provide information to help you determine the problem

In the example above, the file name given was theofficefacts.py , the line number was 5, and the caret pointed to the closing quote of the dictionary key michael . The SyntaxError traceback might not point to the real problem, but it will point to the first place where the interpreter couldn’t make sense of the syntax.

There are two other exceptions that you might see Python raise. These are equivalent to SyntaxError but have different names:

These exceptions both inherit from the SyntaxError class, but they’re special cases where indentation is concerned. An IndentationError is raised when the indentation levels of your code don’t match up. A TabError is raised when your code uses both tabs and spaces in the same file. You’ll take a closer look at these exceptions in a later section.

Common Syntax Problems

When you encounter a SyntaxError for the first time, it’s helpful to know why there was a problem and what you might do to fix the invalid syntax in your Python code. In the sections below, you’ll see some of the more common reasons that a SyntaxError might be raised and how you can fix them.

Misusing the Assignment Operator ( = )

There are several cases in Python where you’re not able to make assignments to objects. Some examples are assigning to literals and function calls. In the code block below, you can see a few examples that attempt to do this and the resulting SyntaxError tracebacks:

The first example tries to assign the value 5 to the len() call. The SyntaxError message is very helpful in this case. It tells you that you can’t assign a value to a function call.

The second and third examples try to assign a string and an integer to literals. The same rule is true for other literal values. Once again, the traceback messages indicate that the problem occurs when you attempt to assign a value to a literal.

Note: The examples above are missing the repeated code line and caret ( ^ ) pointing to the problem in the traceback. The exception and traceback you see will be different when you’re in the REPL vs trying to execute this code from a file. If this code were in a file, then you’d get the repeated code line and caret pointing to the problem, as you saw in other cases throughout this tutorial.

It’s likely that your intent isn’t to assign a value to a literal or a function call. For instance, this can occur if you accidentally leave off the extra equals sign ( = ), which would turn the assignment into a comparison. A comparison, as you can see below, would be valid:

Most of the time, when Python tells you that you’re making an assignment to something that can’t be assigned to, you first might want to check to make sure that the statement shouldn’t be a Boolean expression instead. You may also run into this issue when you’re trying to assign a value to a Python keyword, which you’ll cover in the next section.

Misspelling, Missing, or Misusing Python Keywords

Python keywords are a set of protected words that have special meaning in Python. These are words you can’t use as identifiers, variables, or function names in your code. They’re a part of the language and can only be used in the context that Python allows.

There are three common ways that you can mistakenly use keywords:

1. Misspelling a keyword
2. Missing a keyword
3. Misusing a keyword

If you misspell a keyword in your Python code, then you’ll get a SyntaxError . For example, here’s what happens if you spell the keyword for incorrectly:

The message reads SyntaxError: invalid syntax , but that’s not very helpful. The traceback points to the first place where Python could detect that something was wrong. To fix this sort of error, make sure that all of your Python keywords are spelled correctly.

Another common issue with keywords is when you miss them altogether:

Once again, the exception message isn’t that helpful, but the traceback does attempt to point you in the right direction. If you move back from the caret, then you can see that the in keyword is missing from the for loop syntax.

You can also misuse a protected Python keyword. Remember, keywords are only allowed to be used in specific situations. If you use them incorrectly, then you’ll have invalid syntax in your Python code. A common example of this is the use of continue or break outside of a loop. This can easily happen during development when you’re implementing things and happen to move logic outside of a loop:

Here, Python does a great job of telling you exactly what’s wrong. The messages «‘break’ outside loop» and «‘continue’ not properly in loop» help you figure out exactly what to do. If this code were in a file, then Python would also have the caret pointing right to the misused keyword.

Another example is if you attempt to assign a Python keyword to a variable or use a keyword to define a function:

When you attempt to assign a value to pass , or when you attempt to define a new function called pass , you’ll get a SyntaxError and see the «invalid syntax» message again.

It might be a little harder to solve this type of invalid syntax in Python code because the code looks fine from the outside. If your code looks good, but you’re still getting a SyntaxError , then you might consider checking the variable name or function name you want to use against the keyword list for the version of Python that you’re using.

The list of protected keywords has changed with each new version of Python. For example, in Python 3.6 you could use await as a variable name or function name, but as of Python 3.7, that word has been added to the keyword list. Now, if you try to use await as a variable or function name, this will cause a SyntaxError if your code is for Python 3.7 or later.

Another example of this is print , which differs in Python 2 vs Python 3:

print is a keyword in Python 2, so you can’t assign a value to it. In Python 3, however, it’s a built-in function that can be assigned values.

You can run the following code to see the list of keywords in whatever version of Python you’re running:

keyword also provides the useful keyword.iskeyword() . If you just need a quick way to check the pass variable, then you can use the following one-liner:

This code will tell you quickly if the identifier that you’re trying to use is a keyword or not.

Missing Parentheses, Brackets, and Quotes

Often, the cause of invalid syntax in Python code is a missed or mismatched closing parenthesis, bracket, or quote. These can be hard to spot in very long lines of nested parentheses or longer multi-line blocks. You can spot mismatched or missing quotes with the help of Python’s tracebacks:

Here, the traceback points to the invalid code where there’s a t’ after a closing single quote. To fix this, you can make one of two changes:

1. Escape the single quote with a backslash ( ‘don’t’ )
2. Surround the entire string in double-quotes instead ( «don’t» )

Another common mistake is to forget to close string. With both double-quoted and single-quoted strings, the situation and traceback are the same:

This time, the caret in the traceback points right to the problem code. The SyntaxError message, «EOL while scanning string literal» , is a little more specific and helpful in determining the problem. This means that the Python interpreter got to the end of a line (EOL) before an open string was closed. To fix this, close the string with a quote that matches the one you used to start it. In this case, that would be a double quote ( » ).

Quotes missing from statements inside an f-string can also lead to invalid syntax in Python:

Here, the reference to the ages dictionary inside the printed f-string is missing the closing double quote from the key reference. The resulting traceback is as follows:

Python identifies the problem and tells you that it exists inside the f-string. The message «unterminated string» also indicates what the problem is. The caret in this case only points to the beginning of the f-string.

This might not be as helpful as when the caret points to the problem area of the f-string, but it does narrow down where you need to look. There’s an unterminated string somewhere inside that f-string. You just have to find out where. To fix this problem, make sure that all internal f-string quotes and brackets are present.

The situation is mostly the same for missing parentheses and brackets. If you leave out the closing square bracket from a list, for example, then Python will spot that and point it out. There are a few variations of this, however. The first is to leave the closing bracket off of the list:

When you run this code, you’ll be told that there’s a problem with the call to print() :

What’s happening here is that Python thinks the list contains three elements: 1 , 2 , and 3 print(foo()) . Python uses whitespace to group things logically, and because there’s no comma or bracket separating 3 from print(foo()) , Python lumps them together as the third element of the list.

Another variation is to add a trailing comma after the last element in the list while still leaving off the closing square bracket:

Now you get a different traceback:

In the previous example, 3 and print(foo()) were lumped together as one element, but here you see a comma separating the two. Now, the call to print(foo()) gets added as the fourth element of the list, and Python reaches the end of the file without the closing bracket. The traceback tells you that Python got to the end of the file (EOF), but it was expecting something else.

In this example, Python was expecting a closing bracket ( ] ), but the repeated line and caret are not very helpful. Missing parentheses and brackets are tough for Python to identify. Sometimes the only thing you can do is start from the caret and move backward until you can identify what’s missing or wrong.

Mistaking Dictionary Syntax

You saw earlier that you could get a SyntaxError if you leave the comma off of a dictionary element. Another form of invalid syntax with Python dictionaries is the use of the equals sign ( = ) to separate keys and values, instead of the colon:

Once again, this error message is not very helpful. The repeated line and caret, however, are very helpful! They’re pointing right to the problem character.

This type of issue is common if you confuse Python syntax with that of other programming languages. You’ll also see this if you confuse the act of defining a dictionary with a dict() call. To fix this, you could replace the equals sign with a colon. You can also switch to using dict() :

You can use dict() to define the dictionary if that syntax is more helpful.

Using the Wrong Indentation

There are two sub-classes of SyntaxError that deal with indentation issues specifically:

While other programming languages use curly braces to denote blocks of code, Python uses whitespace. That means that Python expects the whitespace in your code to behave predictably. It will raise an IndentationError if there’s a line in a code block that has the wrong number of spaces:

This might be tough to see, but line 5 is only indented 2 spaces. It should be in line with the for loop statement, which is 4 spaces over. Thankfully, Python can spot this easily and will quickly tell you what the issue is.

There’s also a bit of ambiguity here, though. Is the print(‘done’) line intended to be after the for loop or inside the for loop block? When you run the above code, you’ll see the following error:

Even though the traceback looks a lot like the SyntaxError traceback, it’s actually an IndentationError . The error message is also very helpful. It tells you that the indentation level of the line doesn’t match any other indentation level. In other words, print(‘done’) is indented 2 spaces, but Python can’t find any other line of code that matches this level of indentation. You can fix this quickly by making sure the code lines up with the expected indentation level.

The other type of SyntaxError is the TabError , which you’ll see whenever there’s a line that contains either tabs or spaces for its indentation, while the rest of the file contains the other. This might go hidden until Python points it out to you!

If your tab size is the same width as the number of spaces in each indentation level, then it might look like all the lines are at the same level. However, if one line is indented using spaces and the other is indented with tabs, then Python will point this out as a problem:

Here, line 5 is indented with a tab instead of 4 spaces. This code block could look perfectly fine to you, or it could look completely wrong, depending on your system settings.

Python, however, will notice the issue immediately. But before you run the code to see what Python will tell you is wrong, it might be helpful for you to see an example of what the code looks like under different tab width settings:

Notice the difference in display between the three examples above. Most of the code uses 4 spaces for each indentation level, but line 5 uses a single tab in all three examples. The width of the tab changes, based on the tab width setting:

• If the tab width is 4, then the print statement will look like it’s outside the for loop. The console will print ‘done’ at the end of the loop.
• If the tab width is 8, which is standard for a lot of systems, then the print statement will look like it’s inside the for loop. The console will print ‘done’ after each number.
• If the tab width is 3, then the print statement looks out of place. In this case, line 5 doesn’t match up with any indentation level.

When you run the code, you’ll get the following error and traceback:

Notice the TabError instead of the usual SyntaxError . Python points out the problem line and gives you a helpful error message. It tells you clearly that there’s a mixture of tabs and spaces used for indentation in the same file.

The solution to this is to make all lines in the same Python code file use either tabs or spaces, but not both. For the code blocks above, the fix would be to remove the tab and replace it with 4 spaces, which will print ‘done’ after the for loop has finished.

Defining and Calling Functions

You might run into invalid syntax in Python when you’re defining or calling functions. For example, you’ll see a SyntaxError if you use a semicolon instead of a colon at the end of a function definition:

The traceback here is very helpful, with the caret pointing right to the problem character. You can clear up this invalid syntax in Python by switching out the semicolon for a colon.

In addition, keyword arguments in both function definitions and function calls need to be in the right order. Keyword arguments always come after positional arguments. Failure to use this ordering will lead to a SyntaxError :

Here, once again, the error message is very helpful in telling you exactly what is wrong with the line.

Changing Python Versions

Sometimes, code that works perfectly fine in one version of Python breaks in a newer version. This is due to official changes in language syntax. The most well-known example of this is the print statement, which went from a keyword in Python 2 to a built-in function in Python 3:

This is one of the examples where the error message provided with the SyntaxError shines! Not only does it tell you that you’re missing parenthesis in the print call, but it also provides the correct code to help you fix the statement.

Another problem you might encounter is when you’re reading or learning about syntax that’s valid syntax in a newer version of Python, but isn’t valid in the version you’re writing in. An example of this is the f-string syntax, which doesn’t exist in Python versions before 3.6:

In versions of Python before 3.6, the interpreter doesn’t know anything about the f-string syntax and will just provide a generic «invalid syntax» message. The problem, in this case, is that the code looks perfectly fine, but it was run with an older version of Python. When in doubt, double-check which version of Python you’re running!

Python syntax is continuing to evolve, and there are some cool new features introduced in Python 3.8:

If you want to try out some of these new features, then you need to make sure you’re working in a Python 3.8 environment. Otherwise, you’ll get a SyntaxError .

Python 3.8 also provides the new SyntaxWarning . You’ll see this warning in situations where the syntax is valid but still looks suspicious. An example of this would be if you were missing a comma between two tuples in a list. This would be valid syntax in Python versions before 3.8, but the code would raise a TypeError because a tuple is not callable:

This TypeError means that you can’t call a tuple like a function, which is what the Python interpreter thinks you’re doing.

In Python 3.8, this code still raises the TypeError , but now you’ll also see a SyntaxWarning that indicates how you can go about fixing the problem:

The helpful message accompanying the new SyntaxWarning even provides a hint ( «perhaps you missed a comma?» ) to point you in the right direction!

Conclusion

In this tutorial, you’ve seen what information the SyntaxError traceback gives you. You’ve also seen many common examples of invalid syntax in Python and what the solutions are to those problems. Not only will this speed up your workflow, but it will also make you a more helpful code reviewer!

When you’re writing code, try to use an IDE that understands Python syntax and provides feedback. If you put many of the invalid Python code examples from this tutorial into a good IDE, then they should highlight the problem lines before you even get to execute your code.

Getting a SyntaxError while you’re learning Python can be frustrating, but now you know how to understand traceback messages and what forms of invalid syntax in Python you might come up against. The next time you get a SyntaxError , you’ll be better equipped to fix the problem quickly!

Watch Now This tutorial has a related video course created by the Real Python team. Watch it together with the written tutorial to deepen your understanding: Identify Invalid Python Syntax

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About Chad Hansen

Chad is an avid Pythonista and does web development with Django fulltime. Chad lives in Utah with his wife and six kids.

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Источник

Variables cannot be assigned to literal values like strings or numbers. If you try to assign a variable to a literal, you’ll encounter the “SyntaxError: can’t assign to literal” error.

This guide discusses what this error means and why you may encounter it. We’ll explore an example of how to fix this error so that you can build the knowledge you need to solve this error in your own code.

SyntaxError: can’t assign to literal

A variable is a unique identifier for a value. When you reference a variable, Python will read the value associated with that variable. Python uses an equals sign to assign values to a variable:

“language” is the name of our variable. The equals sign tells Python we are assigning a value to the variable. “Python” is the value that is associated with our variable.

Variables are containers for values. They are not values in themselves. This means you cannot give a variable a name that is equal to a value. If variable names could be equal to a value, Python would not be able to distinguish variables from values.

Variables cannot be strings, booleans, or any other data type. They must be declared using the syntax that we discussed above.

An Example Scenario

We’re going to build a program that calculates a discount for a product in a donut store. To start, ask the user to insert a price of a donut:

"price" = float(input("Enter the price of a donut: "))

Next, ask the user to choose the percentage discount that should be applied to the donut:

"discount" = float(input("Enter the discount percentage: "))

The input() method returns a string. We cannot run mathematical operations on a string so we need to convert the data we gather to a numerical value.  We’ve converted both of these values to floats using the float() method.

Now that we have these two values, we can calculate the discounted price:

discounted_price = round(price - ((price / 100) * discount), 2)

print("The new cost of a donut is ${}.".format(discounted_price))

We calculate the discounted price using a percentage decrease formula. We round the discounted price to the nearest two decimal places. Then, we print out the discounted price to the console.

Let’s run the code:

  File "main.py", line 1
	"price" = input("Enter the price of a donut: ")
	^
SyntaxError: cannot assign to literal

We have run into an error.

The Solution

“price” is a literal value. It is a string. We have tried to assign a value to this literal. This causes an error because variable names must be identifiers, not values.

We can fix this error by removing the quotation marks around our first two variables:

price = float(input("Enter the price of a donut: "))
discount = float(input("Enter the discount percentage: "))

Our variables now have unique identifiers. We can use the labels price and discount to identify these values. Let’s run our program:

Enter the price of a donut: 2.20
Enter the discount percentage: 5
The new cost of a donut is $2.09.

Our code successfully calculates the discounted value of a product.

Conclusion

The “SyntaxError: can’t assign to literal” error occurs when you try to assign a value to a literal value such as a boolean, a string, a list, or a number. To solve this error, ensure your variable names are names rather than values.

Now you have the knowledge you need to fix this error like a professional!

✋ Update: This post was originally published on my blog decodingweb.dev, where you can read the latest version for a 💯 user experience. ~reza

Python raises “SyntaxError: cannot assign to literal here. Maybe you meant ‘==’ instead of ‘=’?” when you assign a value to a literal (e.g., 12, '49.5', 'Sally'). On the other hand, this error occurs if a literal value is the left-hand side operand in a value assignment:

# 🚫 Raises SyntaxError
12 = 'Hi I am the value being assigned to 12!'

Additionally, Python provides you a hint, assuming you meant to use the equality operator (==):

File /dwd/sandbox/test.py, line 2
    12 = 'Hi I am the value being assigned to 12!'
    ^^
SyntaxError: cannot assign to literal here. Maybe you meant '==' instead of '='?

But what’s a literal? You may ask.

The term «literal» refers to an actual value in the source code. All the following values are literals:

• 'someValue'
• 12.5
• 23
• True

Most of the time, the reason is a typo in your code — usually a missing = or invalid syntax in assignment statements.

How to fix «SyntaxError: cannot assign to literal here»

The long error «SyntaxError: cannot assign to literal here. Maybe you meant ‘==’ instead of ‘=’?» occurs under various scenarios:

1. Wrong left-hand side operand in an assignment statement
2. Multiple value assignments on a single line
3. In valid comparison statement

Let’s see some examples.

Wrong left-hand side operand in an assignment statements: Assignment statements bind names to values. (e.g., price = 49.99)

Based on Python syntax and semantics, the left-hand side of the assignment operator (=) should always be an identifier, not a literal value.

Identifiers (a.k.a names) are arbitrary names you use for definitions in the source code, such as variable names, function names, and class names. For instance, in the statement age = 25, age is the identifier.

Python identifiers are based on the Unicode standard annex UAX-31, which describes the specifications for using Unicode in identifiers.

That said, you can’t have a literal value (e.g. 12, 45.9, 'stringValue') as the identifier, otherwise, you’ll get the «SyntaxError: cannot assign to literal here. Maybe you meant ‘==’ instead of ‘=’?» error.

# 🚫 Raises SyntaxError
'age' = 12
4.9 = score

So if your code looks like the above, here’s how to fix it:

# ✅ Correct value assignment
age = 12
score = 4.9

Multiple value assignments on a single line: This is more affecting Python 2.7 users since Python 3 outputs a different error message. On Python 2.7, you’ll get the «SyntaxError: can’t assign to literal» error, if you initialize your variables like so:

# Raises SyntaxError: can't assign to literal
x = 12, y = 45

To fix the issue, you need to change your code like so:

# ✅ Correct way of having multiple assignments on a single line
x, y = 12, 45

Alternatively, you can use semi-colons (;) to have multiple assignment statements on a single line:

# ✅ Correct way of having multiple assignments on a single line
x = 12; y = 45

Invalid comparison statement: Another cause of «SyntaxError: cannot assign to literal here» is using an invalid sequence of comparison operators while comparing values.

This one is more of a syntax-related mistake and rarely finds its way to the runtime, but it’s worth watching.

Imagine you want to check if age is between 12 and 25 (12 <= age < = 25), however, you miss one of the < operators:

age = 12

# 🚫 Raises SyntaxError
if 12 = age <= 25:
    print('User is eligible')

In the above code, once Python’s interpreter encounters the first =, it assumes you’re trying to assign age to 12 (= is a value assignment operator).

Once we add the missing <, the misconception goes away:

age = 12

# ✅ Correct sequence
if 12 <= age <= 25:
    print('User is eligible')

Problem solved!

Alright, I think it does it. I hope this quick guide helped you solve your problem.

Thanks for reading.

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Неверный синтаксис в Python

Когда вы запускаете ваш код Python, интерпретатор сначала анализирует его, чтобы преобразовать в байтовый код Python, который он затем выполнит. Интерпретатор найдет любой недопустимый синтаксис в Python на этом первом этапе выполнения программы, также известном как этап синтаксического анализа . Если интерпретатор не может успешно проанализировать ваш код Python, это означает, что вы использовали неверный синтаксис где-то в вашем коде. Переводчик попытается показать вам, где произошла эта ошибка.

Когда вы изучаете Python в первый раз, может быть неприятно получить + SyntaxError +. Python попытается помочь вам определить, где в вашем коде указан неверный синтаксис, но предоставляемый им traceback может немного сбить с толку. Иногда код, на который он указывает, вполне подходит.

*Примечание:* Если ваш код *синтаксически* правильный, то вы можете получить другие исключения, которые не являются `+ SyntaxError +`. Чтобы узнать больше о других исключениях Python и о том, как их обрабатывать, ознакомьтесь с https://realpython.com/python-exceptions/[Python Exceptions: Введение].

Вы не можете обрабатывать неправильный синтаксис в Python, как и другие исключения. Даже если вы попытаетесь обернуть блок + try + и + кроме + вокруг кода с неверным синтаксисом, вы все равно увидите, что интерпретатор вызовет + SyntaxError +.

+ SyntaxError + Исключение и трассировка

Когда интерпретатор обнаруживает неверный синтаксис в коде Python, он вызовет исключение + SyntaxError + и предоставит трассировку с некоторой полезной информацией, которая поможет вам отладить ошибку. Вот некоторый код, который содержит недопустимый синтаксис в Python:

 1 # theofficefacts.py
 2 ages = {
 3     'pam': 24,
 4     'jim': 24
 5     'michael': 43
 6 }
 7 print(f'Michael is {ages["michael"]} years old.')

Вы можете увидеть недопустимый синтаксис в литерале словаря в строке 4. Во второй записи + 'jim' + пропущена запятая. Если вы попытаетесь запустить этот код как есть, вы получите следующую трассировку:

$ python theofficefacts.py
File "theofficefacts.py", line 5
    'michael': 43
            ^
SyntaxError: invalid syntax

Обратите внимание, что сообщение трассировки обнаруживает ошибку в строке 5, а не в строке 4. Интерпретатор Python пытается указать, где находится неправильный синтаксис. Тем не менее, он может только указать, где он впервые заметил проблему. Когда вы получите трассировку + SyntaxError + и код, на который указывает трассировка, выглядит нормально, тогда вы захотите начать движение назад по коду, пока не сможете определить, что не так.

В приведенном выше примере нет проблемы с запятой, в зависимости от того, что следует после нее. Например, нет проблемы с отсутствующей запятой после + 'michael' + в строке 5. Но как только переводчик сталкивается с чем-то, что не имеет смысла, он может лишь указать вам на первое, что он обнаружил, что он не может понять.

*Примечание:* В этом руководстве предполагается, что вы знакомы с основами *tracebacks* в Python. Чтобы узнать больше о трассировке Python и о том, как их читать, ознакомьтесь с https://realpython.com/python-traceback/[Understanding Python Traceback].

Существует несколько элементов трассировки + SyntaxError +, которые могут помочь вам определить, где в вашем коде содержится неверный синтаксис:

В приведенном выше примере имя файла было + theofficefacts.py +, номер строки был 5, а каретка указывала на закрывающую кавычку из словарного ключа + michael +. Трассировка + SyntaxError + может не указывать на реальную проблему, но она будет указывать на первое место, где интерпретатор не может понять синтаксис.

Есть два других исключения, которые вы можете увидеть в Python. Они эквивалентны + SyntaxError +, но имеют разные имена:

Оба эти исключения наследуются от класса + SyntaxError +, но это особые случаи, когда речь идет об отступе. + IndentationError + возникает, когда уровни отступа вашего кода не совпадают. + TabError + возникает, когда ваш код использует и табуляцию, и пробелы в одном файле. Вы познакомитесь с этими исключениями более подробно в следующем разделе.

Общие проблемы с синтаксисом

Когда вы впервые сталкиваетесь с + SyntaxError +, полезно знать, почему возникла проблема и что вы можете сделать, чтобы исправить неверный синтаксис в вашем коде Python. В следующих разделах вы увидите некоторые из наиболее распространенных причин, по которым может быть вызвано «+ SyntaxError +», и способы их устранения.

>>> len('hello') = 5
  File "<stdin>", line 1
SyntaxError: can't assign to function call

>>> 'foo' = 1
  File "<stdin>", line 1
SyntaxError: can't assign to literal

>>> 1 = 'foo'
  File "<stdin>", line 1
SyntaxError: can't assign to literal

*Примечание:* В приведенных выше примерах отсутствует повторяющаяся строка кода и каретка (`+ ^ +`), указывающая на проблему в трассировке. Исключение и обратная трассировка, которые вы видите, будут другими, когда вы находитесь в REPL и пытаетесь выполнить этот код из файла. Если бы этот код был в файле, то вы бы получили повторяющуюся строку кода и указали на проблему, как вы видели в других случаях в этом руководстве.

>>> len('hello') == 5
True

>>> fro i in range(10):
  File "<stdin>", line 1
    fro i in range(10):
        ^
SyntaxError: invalid syntax

>>> for i range(10):
  File "<stdin>", line 1
    for i range(10):
              ^
SyntaxError: invalid syntax

>>> names = ['pam', 'jim', 'michael']
>>> if 'jim' in names:
...     print('jim found')
...     break
...
  File "<stdin>", line 3
SyntaxError: 'break' outside loop

>>> if 'jim' in names:
...     print('jim found')
...     continue
...
  File "<stdin>", line 3
SyntaxError: 'continue' not properly in loop

>>> pass = True
  File "<stdin>", line 1
    pass = True
         ^
SyntaxError: invalid syntax

>>> def pass():
  File "<stdin>", line 1
    def pass():
           ^
SyntaxError: invalid syntax

import keyword
print(keyword.kwlist)

>>> import keyword; keyword.iskeyword('pass')
True

>>> message = 'don't'
  File "<stdin>", line 1
    message = 'don't'
                   ^
SyntaxError: invalid syntax

>>> message = "This is an unclosed string
  File "<stdin>", line 1
    message = "This is an unclosed string
                                        ^
SyntaxError: EOL while scanning string literal

 1 # theofficefacts.py
 2 ages = {
 3     'pam': 24,
 4     'jim': 24,
 5     'michael': 43
 6 }
 7 print(f'Michael is {ages["michael]} years old.')

$ python theofficefacts.py
  File "theofficefacts.py", line 7
    print(f'Michael is {ages["michael]} years old.')
         ^
SyntaxError: f-string: unterminated string

# missing.py
def foo():
    return [1, 2, 3

print(foo())

$ python missing.py
  File "missing.py", line 5
    print(foo())
        ^
SyntaxError: invalid syntax

# missing.py
def foo():
    return [1, 2, 3,

print(foo())

$ python missing.py
  File "missing.py", line 6

                ^
SyntaxError: unexpected EOF while parsing

>>> ages = {'pam'=24}
  File "<stdin>", line 1
    ages = {'pam'=24}
                 ^
SyntaxError: invalid syntax

>>> ages = dict(pam=24)
>>> ages
{'pam': 24}

 1 # indentation.py
 2 def foo():
 3     for i in range(10):
 4         print(i)
 5   print('done')
 6
 7 foo()

$ python indentation.py
  File "indentation.py", line 5
    print('done')
                ^
IndentationError: unindent does not match any outer indentation level

 1 # indentation.py
 2 def foo():
 3     for i in range(10):
 4         print(i)
 5     print('done')
 6
 7 foo()

$ tabs 4 # Sets the shell tab width to 4 spaces
$ cat -n indentation.py
     1   # indentation.py
     2   def foo():
     3       for i in range(10)
     4           print(i)
     5       print('done')
     6
     7   foo()

$ tabs 8 # Sets the shell tab width to 8 spaces (standard)
$ cat -n indentation.py
     1   # indentation.py
     2   def foo():
     3       for i in range(10)
     4           print(i)
     5           print('done')
     6
     7   foo()

$ tabs 3 # Sets the shell tab width to 3 spaces
$ cat -n indentation.py
     1   # indentation.py
     2   def foo():
     3       for i in range(10)
     4           print(i)
     5      print('done')
     6
     7   foo()

$ python indentation.py
  File "indentation.py", line 5
    print('done')
                ^
TabError: inconsistent use of tabs and spaces in indentation

>>> def fun();
  File "<stdin>", line 1
    def fun();
             ^
SyntaxError: invalid syntax

>>> def fun(a, b):
...     print(a, b)
...
>>> fun(a=1, 2)
  File "<stdin>", line 1
SyntaxError: positional argument follows keyword argument

>>> # Valid Python 2 syntax that fails in Python 3
>>> print 'hello'
  File "<stdin>", line 1
    print 'hello'
                ^
SyntaxError: Missing parentheses in call to 'print'. Did you mean print('hello')?

>>> # Any version of python before 3.6 including 2.7
>>> w ='world'
>>> print(f'hello, {w}')
  File "<stdin>", line 1
    print(f'hello, {w}')
                      ^
SyntaxError: invalid syntax

>>> [(1,2)(2,3)]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'tuple' object is not callable

>>> [(1,2)(2,3)]
<stdin>:1: SyntaxWarning: 'tuple' object is not callable; perhaps you missed a comma?
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'tuple' object is not callable

Заключение

В этом руководстве вы увидели, какую информацию предоставляет обратная связь + SyntaxError +. Вы также видели много распространенных примеров неправильного синтаксиса в Python и каковы решения этих проблем. Это не только ускорит ваш рабочий процесс, но и сделает вас более полезным рецензентом кода!

Когда вы пишете код, попробуйте использовать IDE, который понимает синтаксис Python и предоставляет обратную связь. Если вы поместите многие из недопустимых примеров кода Python из этого руководства в хорошую IDE, то они должны выделить проблемные строки, прежде чем вы даже сможете выполнить свой код.

Получение + SyntaxError + во время изучения Python может быть неприятным, но теперь вы знаете, как понимать сообщения трассировки и с какими формами недопустимого синтаксиса в Python вы можете столкнуться. В следующий раз, когда вы получите + SyntaxError +, у вас будет больше возможностей быстро решить проблему!

Asked by: Jarod Larkin

Score: 4.8/5
(63 votes)

The “SyntaxError: can’t assign to literal” error occurs when you try to assign a value to a literal value such as a boolean, a string, a list, or a number. To solve this error, ensure your variable names are names rather than values.

How do you assign a literal?

How do you fix SyntaxError Cannot assign to operator?

The SyntaxError: cannot assign to operator error is raised when you try to evaluate a mathematical statement before an assignment operator. To fix this error, make sure all your variable names appear on the left hand side of an assignment operator and all your mathematical statements appear on the right.

Can’t assign to function call pandas?

The “SyntaxError: can’t assign to function call” error is raised when you try to assign a function call to a variable. This happens if you assign the value of a function call to a variable in reverse order. To solve this error, make sure you use the correct syntax to declare a variable.

What is Python literal?

Generally, literals are a notation for representing a fixed value in source code. They can also be defined as raw value or data given in variables or constants. Example: Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.

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