← Errors
A NameError is raised in Python when you try to use a variable or function name that has not been defined in the current scope. Python looks up the name in local, enclosing, global, and built-in scopes and cannot find it.
Why it happens
- •Using a variable before assigning a value to it.
- •Typo in the variable or function name.
- •Trying to use a name that is only defined inside a function from outside it.
- •Forgetting to import a module before using its contents.
Examples
Python
Code that triggers the error
def greet():
print(message)
greet()Error output
Traceback (most recent call last):
File "app.py", line 4, in <module>
greet()
File "app.py", line 2, in greet
print(message)
NameError: name 'message' is not definedHow to fix it
Define the variable before using it. Double-check the spelling of every name. If a variable is defined inside a function, pass it as an argument or return it rather than accessing it from the outer scope. Use an IDE or linter to catch undefined names early.
Fixed code
message = "Hello, world!"
def greet():
print(message)
greet() # Hello, world!Related errors
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