What are the regular expression quantifiers?

Regular expression quantifiers include:, ,?,{n},{n,},{n,m},?, ,*, etc. Detailed introduction: 1.: Indicates matching the previous element 0 or more times. For example, ab can match a or ab or abbb, etc.; 2. : means matching the previous element one or more times. For example, ab can match ab or abbb, etc.; 3. ?: means matching the previous element 0 or 1 times. For example, ab? can match a or ab; 4. {n}: means matching the previous element exactly n times. For example, a{2} can match aa and so on.

Operating system for this tutorial: Windows 10 system, Dell G3 computer.

Regular expression quantifiers are special symbols used to specify the number of matches. The following are common regular expression quantifiers:

1. : Indicates matching the previous element 0 or more times. For example, ab can match a or ab or abbb, etc.

2. : Indicates matching the previous element one or more times. For example, ab can match ab or abbb, etc.

3. ?: Indicates matching the previous element 0 or 1 times. For example, ab? matches a or ab.

4. {n}: Indicates matching the previous element exactly n times. For example, a{2} matches aa.

5. {n,}: Indicates matching the previous element at least n times. For example, a{2,} can match strings such as aa, aaa, aaaa, etc.

6. {n,m}: Indicates matching the previous element at least n times, but not more than m times. For example, a{2,3} can match aa, aaa, but not aaaa.

7. ?: Indicates matching the previous element 0 or 1 times. For example, [0-9]? can match 0 or 1 number.

8. : Indicates matching the previous element one or more times. For example, [0-9] can match 1 or more numbers.

9. *: Indicates matching the previous element 0 or more times. For example, [0-9]* can match 0 or more numbers.

These quantifiers can be used to specify the number of repetitions of characters in a regular expression, allowing for more precise pattern matching. Note that different regular expression engines may support different quantifier syntax and functionality.

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