Which of the literals below is not a valid function name?

Question

Options

• AFunction_1
• BFunction1
• C_function1
• D1function
• EFunc_1_tion

• A
  3% (2)
• B
  3% (2)
• C
  2% (1)
• D
  84% (51)
• E
  8% (5)

Explanation

Option D (1function) is invalid because identifiers in most programming languages cannot begin with a digit - names must start with a letter or underscore. Options A (Function_1), B (Function1), C (_function1), and E (Func_1_tion) are all valid because they each start with either a letter or an underscore, and contain only letters, digits, and underscores thereafter. The key rule is about the first character: digits are allowed anywhere in a name except the very beginning.

Memory tip: Think "letters and underscores lead, digits follow" - if a name starts with a number, it's dead on arrival.

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