What's the Difference Between ' ' and '*' Quantifiers in Regular Expressions?

Understanding the Difference Between ' ' and '*' Quantifiers in Regular Expressions

In PHP's preg_match regular expression, the operators and * are used as quantifiers to specify the number of occurrences of a preceding character or pattern. Here's a breakdown of their differences:

' ' Quantifier

The ' ' quantifier represents "one or more" occurrences of the preceding expression. It matches at least one instance of the pattern, but it can match more if present.

Example:

(.+?)

This regex matches a non-empty string of characters.

'*' Quantifier

The '*' quantifier represents "zero or more" occurrences of the preceding expression. It matches any number of times, including none.

Example:

(.*?)

This regex matches any number (including zero) of characters.

Greedy vs. Ungreedy Quantifiers

By default, quantifiers are greedy, meaning they match as much as possible. However, adding a '?' after the quantifier makes it ungreedy, causing it to match as little as possible.

Example:

a.*?b

In this case, the .*? matches the fewest number of characters possible to find the first 'b' after the 'a'.

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