Solve Python error: NameError: name 'xxx' is not defined

Solution to Python error: NameError: name 'xxx' is not defined

In the process of writing code in Python, we often encounter various Report an error. One of them is NameError: name 'xxx' is not defined, which means that Python cannot find the referenced variable or function name. This error is usually caused by the following reasons: the variable or function name is misspelled, the variable or function is not defined in the correct scope, or the variable or function is not assigned or defined before use.

So, how do we solve this problem? Below I will give some common solutions and attach code examples to help you better understand and deal with this error.

1. Check whether the spelling of the variable or function name is correct
When we use an undefined variable or function in the code, Python will throw a NameError. First, we should check to see if it could be caused by a misspelling of a variable or function name. Especially in the case of long names, it is easy to make spelling errors, so check them very carefully.

Code example:

# 错误的写法：变量名拼写错误
name = "Alice"
print(nmae)  # 正确的应该是print(name)

2. Check whether the variable or function is defined in the correct scope
The variable scope in Python has global scope and local scope. If we reference a variable or function defined outside the local scope in the local scope, a NameError will occur. At this point, we need to ensure that the variable or function is defined and used in the correct scope.

Code example:

# 错误的写法：变量在函数外定义，但在函数内使用
def print_name():
    print(name)  # 正确的应该是在函数内定义并使用name变量

name = "Bob"
print_name()

3. Check whether the variable or function is assigned or defined before use
When we use an unassigned or undefined variable or function in the code , Python will throw NameError. At this point, we need to make sure we assign or define the variable or function before using it.

Code example:

# 错误的写法：变量在使用之前没有赋值
age = age + 1  # 正确的应该是先给变量age赋一个初始值

age = 18
age = age + 1
print(age)

The above are some common solutions. I hope they can help you solve the error NameError: name 'xxx' is not defined. Of course, in the actual development process, we must also pay attention to writing standardized code to avoid spelling errors, scope problems and variable assignment problems. In addition, for more complex error reports, we can find the problem more accurately by viewing Python's error message.

In general, the key to solving the Python error NameError: name 'xxx' is not defined is to carefully check spelling, scope, assignment and other issues. As long as we pay attention to these details, I believe we can easily solve this problem and improve our code quality and development efficiency.

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