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Difference between revisions of "Regular Expressions"
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→Quantifiers: Typo fixes
(→Metacharacters: Added lookahead and look behind) |
m (→Quantifiers: Typo fixes) |
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| <code><nowiki>|</nowiki></code> || Or, alternation || <code>d<nowiki>|</nowiki>fog</code> matches <code>dog</code> or <code>fog</code> | | <code><nowiki>|</nowiki></code> || Or, alternation || <code>d<nowiki>|</nowiki>fog</code> matches <code>dog</code> or <code>fog</code> | ||
|- | |- | ||
| <code>?=</code> || Lookahead || <code>dog(?=,)</code> matches the <code>dog</ | | <code>?=</code> || Lookahead || <code>dog(?=,)</code> matches the <code>dog</code> in <code>dog,</code> but won't find a match in <code>dog</code> | ||
|- | |- | ||
| <code>?<=</code> || Look behind || <code>(?<=big )dog</code> matches the <code>dog</ | | <code>?<=</code> || Look behind || <code>(?<=big )dog</code> matches the <code>dog</code> in <code>big dog</code> but won't find a match in <code>dog</code> | ||
|} | |} | ||
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| <code>?</code> || Match 0 or 1 times only || <code>dog?</code> matches <code>do</code> or <code>dog</code> only | | <code>?</code> || Match 0 or 1 times only || <code>dog?</code> matches <code>do</code> or <code>dog</code> only | ||
|- | |- | ||
| <code>{n}</code> || Match exactly <code>n<code> times || <code>dog{2}</code> matches <code>dogg</code> only | | <code>{n}</code> || Match exactly <code>n</code> times || <code>dog{2}</code> matches <code>dogg</code> only | ||
|- | |- | ||
| <code>{n,}</code> || Match <code>n<code> or more times || <code>dog{2,}</code> matches <code>dogg</code>, or <code>doggg</code>, and so on | | <code>{n,}</code> || Match <code>n</code> or more times || <code>dog{2,}</code> matches <code>dogg</code>, or <code>doggg</code>, and so on | ||
|- | |- | ||
| <code>{n,m}</code> || Match <code>n<code> up to <code>m</code> times || <code>dog{2,4}</code> matches <code>dogg</code>, <code>doggg</code>, or <code>dogggg</code> only | | <code>{n,m}</code> || Match <code>n</code> up to <code>m</code> times || <code>dog{2,4}</code> matches <code>dogg</code>, <code>doggg</code>, or <code>dogggg</code> only | ||
|} | |} | ||