# 30 Regular expressions library [re]

## 30.10 Regular expression algorithms [re.alg]

### 30.10.3regex_­search[re.alg.search]

Table 146: Effects of regex_­search algorithm [tab:re.alg.search]
 ðŸ”— Element Value ðŸ”— m.size() 1 + e.mark_­count() ðŸ”— m.empty() false ðŸ”— m.prefix().first first ðŸ”— m.prefix().second m[0].first ðŸ”— m.prefix().matched m.prefix().first != m.prefix().second ðŸ”— m.suffix().first m[0].second ðŸ”— m.suffix().second last ðŸ”— m.suffix().matched m.suffix().first != m.suffix().second ðŸ”— m[0].first The start of the sequence of characters that matched the regular expression ðŸ”— m[0].second The end of the sequence of characters that matched the regular expression ðŸ”— m[0].matched true ðŸ”— m[n].first For all integers 0 < n < m.size(), the start of the sequence that matched sub-expression n. Alternatively, if sub-expression n did not participate in the match, then last. ðŸ”— m[n].second For all integers 0 < n < m.size(), the end of the sequence that matched sub-expression n. Alternatively, if sub-expression n did not participate in the match, then last. ðŸ”— m[n].matched For all integers 0 < n < m.size(), true if sub-expression n participated in the match, false otherwise.