✋ 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 expression here. Maybe you meant ‘==’ instead of ‘=’?” when you assign a value to an expression. On the other hand, this error occurs if an expression is the left-hand side operand in an assignment statement.
a = 12
b = 2
# 🚫 SyntaxError
a * b = c
Additionally, Python provides you a hint, assuming you meant to use the equality operator (==):
File /dwd/sandbox/test.py, line 5
a * b = c
^^^^^
SyntaxError: cannot assign to expression here. Maybe you meant '==' instead of '='?
But what's an expression? You may ask.
The term "expression" refers to values or combination of values (operands) and operators that result in a value. That said, all the following items are expressions:
'someValue'12 * 24 * (5 + 2)'someText' + 'anotherText'
Most of the time, the cause of the "SyntaxError: cannot assign to expression here" error is a typo in your code - usually a missing = or invalid identifiers in assignment statements.
How to fix "SyntaxError: cannot assign to expression here"
The long error "SyntaxError: cannot assign to expression here. Maybe you meant '==' instead of '='?" occurs under various scenarios:
- Using an invalid name (identifier) in an assignment statement
- Using
=instead of==in a comparison statement
Let's see some examples.
Using an invalid name (identifier) in an assignment statement: Assignment statements bind names to values. (e.g., total_price = 49.99)
Based on Python syntax and semantics, the left-hand side of the assignment operator (=) should always be an identifier, not an expression or a literal.
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 only use alphanumeric characters and underscores for names. Otherwise, you'll get a SyntaxError. For instance, 2 + 2 = a is a syntax error because the left-hand side operator isn't a valid identifier - it's a Python expression.
A common mistake which results in this syntax error is using hyphens (-) in your variable names.
Hyphens are only valid in expressions like 45.54 - 12.12. If you have a '-' in your variable name, Python's interpreter would assume it's an expression:
# 🚫 SyntaxError
total-price = 49.45
In the above code, Python's interpreter assumes you're trying to subtract a variable name price from another variable named total.
And since you can't have an expression as a left-hand side operand in an assignment statement, you'll get this SyntaxError.
So if your code looks like the above, you need to replace the hyphen (-) with an underscore (_):
# ✅ a valid identifier contains alphanumeric characters and underscores
total_price = 49.45
That's much better!
Invalid comparison statement : Another cause of "SyntaxError: cannot assign to expression 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 test if a number is an even number. As you probably know, if we divide a number by 2, and the remainder is 0, that number is even.
In Python, we use the modulo operator (%) to get the remainder of a division:
x = 45
# Checking if x is an even number
# But Python raises:
# 🚫 SyntaxError: cannot assign to literal here. Maybe you meant '==' instead of '='?
if x % 2 = 0:
print('x is even!')
In the above code, once Python encounters the assignment operator (=), it assumes we're trying to assign 0 to x % 2! No wonder the response is "SyntaxError: cannot assign to expression here. Maybe you meant '==' instead of '='?".
But once we use the equality operator (==), the misconception goes away:
x = 34
# Checking if x is an even number
if x % 2 == 0:
print('x is even!')
# Output: x is even!
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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