PCEP Practice Question: Data Types, Variables, Basic I/O and Operators
Which of the following is a valid Python variable name?
⚠ Common exam trap
Python Institute often tests the misconception that hyphens or special characters like '$' are allowed in variable names, or that digits can start a name, because candidates confuse Python's rules with those of other languages like JavaScript or PHP.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
_var
(_var) is correct because Python variable names must start with a letter or an underscore, and can contain letters, digits, or underscores. The underscore is a valid starting character, making _var a legal identifier.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
2var
Why it's wrong here
Python identifiers cannot begin with a digit, so 2var raises a SyntaxError at parse time. It is tempting because digits are permitted elsewhere in a name, such as var2, and the token looks like a label. A leading letter or underscore is required instead.
- ✓
_var
Why this is correct
Underscores are permitted as the first character in Python identifiers, so `_var` satisfies the naming rules. Unlike digits, which cannot start a name, and reserved keywords such as `class`, the underscore prefix is valid. This makes `_var` a legal variable name.
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my-var
Why it's wrong here
The hyphen is Python's subtraction operator, so my-var parses as the expression my minus var, not a single identifier. It is tempting because hyphens are common in filenames and URLs. Only letters, digits and underscores are permitted, so my_var would be valid.
- ✗
var$name
Why it's wrong here
The dollar sign is not a legal Python identifier character, so var$name raises a SyntaxError. It is tempting because $ is valid in shell, PHP and JavaScript identifiers. Python permits only letters, digits and underscores, so varname or var_name would be accepted.
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