For convenience (and historical compatibility) the three most common quantifiers have single-character abbreviations: * is equivalent to {0,} + is equivalent to {1,}? is equivalent to {0,1} It is possible to construct infinite loops by following a subpattern that can match no characters with a quantifier that has no upper limit, for example: (a ?)* Earlier versions of Perl and PCRE used to give an error atFor convenience (and historical compatibility) the three most common quantifiers have single-character abbreviations: * is equivalent to {0,} + is equivalent to {1,}? is equivalent to {0,1} It is possible to construct infinite loops by following a subpattern that can match no characters with a quantifier that has no upper limit, for example: (a? )* Earlier versions of Perl and PCRE used to give an error at compile time for such patterns.
équivalent à {0,1}