In regular expressions, what does the + quantifier indicate?

• A. The preceding item is optional
• B. The preceding item is matched one or more times
• C. One character is matched
• D. Indicates a non-greedy operator

Answer: (B)

One or more occurrences of the preceding element is indicated by the plus quantifier. It requires at least one instance of what comes before it, and it will include as many repetitions as the input allows. For example, a+ matches a, aa, aaa, and so on. In a pattern like ab+c, the plus attaches to the b, so you must have at least one b: it matches abc, abbc, abbbbc, etc. By default, this repetition is greedy, meaning it will consume as many of the preceding characters as possible given the rest of the pattern. If you need a smaller match, you can make it non-greedy by adding a ? after the quantifier, as in a+?.