Python Error: NameError: name 'X' is not defined - Solved

Python Error: 'NameError: name 'X' is not defined' - Solved

This error message indicates that you are trying to access a variable called 'X' in your code, but Python cannot find it. This often happens due to a simple typographical error.

Example of the Error:

x = 11
str(x)
y = type(X)
print(y)

Error Output:

NameError: name 'X' is not defined

Explanation:

In the code above, the variable 'x' is declared as lowercase in the first line but then mistakenly used as uppercase 'X' in the third line. Python is case-sensitive, meaning that 'x' and 'X' are considered different variables.

Solution:

The fix is simply to use the correct variable name consistently. Change 'X' to 'x' in the third line:

x = 11
str(x)
y = type(x)
print(y)

Output:

<class 'int'>

Key Concepts:

• Case Sensitivity: Python treats variables with different capitalization as distinct entities.
• Variable Assignment: The 'x = 11' statement assigns the value 11 to the variable 'x'.
• Type Checking: The type(x) function returns the data type of the variable 'x', which in this case is an integer ('int').

Remember: Double-check your variable names for consistency and pay attention to capitalization! This will help you avoid common Python errors like this one.