LFCS Question #798: Real Exam Question with Answer & Explanation

Question

What does the ? symbol within regular expressions represent?

Options

• AMatch the preceding qualifier one or more times.
• BMatch the preceding qualifier zero or more times.
• CMatch the preceding qualifier zero or one times.
• DMatch a literal ? character.

Explanation

In regular expressions, the ? symbol acts as a quantifier, matching the preceding element zero or one time, making it optional.

Common mistakes.

• A. Matching the preceding qualifier one or more times is represented by the + symbol in regular expressions.
• B. Matching the preceding qualifier zero or more times is represented by the * symbol in regular expressions.
• D. To match a literal ? character in a regular expression, it must be escaped with a backslash, i.e., \?.

Concept tested. Regular expression quantifiers (?)

Reference. https://www.gnu.org/software/grep/manual/grep.html#Regular-Expressions

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