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std::basic_...:basic_regex(3) C++ Standard Libarystd::basic_...:basic_regex(3) NAME std::basic_regex::basic_regex - std::basic_regex::basic_regex Synopsis basic_regex(); (1) (since C++11) explicit basic_regex( const CharT* s, flag_type f = (2) (since C++11) std::regex_constants::ECMAScript ); basic_regex( const CharT* s, std::size_t count, (3) (since C++11) flag_type f = std::regex_constants::ECMAScript ); basic_regex( const basic_regex& other ); (4) (since C++11) basic_regex( basic_regex&& other ) noexcept; (5) (since C++11) template< class ST, class SA > explicit basic_regex( const std::basic_string<CharT,ST,SA>& str, (6) (since C++11) flag_type f = std::regex_constants::ECMAScript ); template< class ForwardIt > basic_regex( ForwardIt first, ForwardIt last, (7) (since C++11) flag_type f = std::regex_constants::ECMAScript ); basic_regex( std::initializer_list<CharT> init, (8) (since C++11) flag_type f = std::regex_constants::ECMAScript ); Constructs a new regular expression from a sequence of characters interpreted according to the flags f. 1) Default constructor. Constructs an empty regular expression which will match nothing. 2) Constructs a regex from a null-terminated string s. 3) Constructs a regex from a sequence of count characters, pointed to by s. 4) Copy constructor. Constructs a regex by copying other. 5) Move constructor. Constructs a regex with the contents of other using move semantics. 6) Constructs a regex from a string str. 7) Range constructor. Constructs the string with the contents of the range [first, last). 8) Initializer list constructor. Constructs the string with the con- tents of the initializer list init. Parameters s - pointer to a null-terminated string count - length of a character sequence used to initialize the regex first, last - range of a character sequence used to initialize the regex str - a basic_string used as a source used to initialize the regex other - another regex to use as source to initialize the regex init - initializer list used to initialize the regex f - flags used to guide the interpretation of the charac- ter sequence as a regular expression Type requirements - ForwardIt must meet the requirements of LegacyForwardIterator. Exceptions 1) May throw implementation-defined exceptions. 2,3) std::regex_error if the supplied regular expression is not valid. 4) May throw implementation-defined exceptions. 6-8) std::regex_error if the supplied regular expression is not valid. Example // Run this code #include <iomanip> #include <iostream> #include <regex> #include <string> void match_and_print(const std::string& text, const std::regex& pat- tern) { std::sregex_iterator it(text.begin(), text.end(), pattern), it_end; int count = 0; for (; it != it_end; ++it) { const std::smatch& match = *it; std::cout << ++count << ". " << std::quoted(match.str()) << '\n'; } std::cout << (count ? "\n" : "no match found\n\n"); } int main() { const std::string text = "Hello, World! 12345"; // Matches one or more digits std::string pattern_text = "\\d+"; std::cout << "digits (" << pattern_text << "):\n"; auto pattern = std::regex(pattern_text); match_and_print(text, pattern); // Matches one or more characters split by space pattern_text = "[^\\s]+"; std::cout << "words (" << pattern_text << "):\n"; pattern = std::regex(pattern_text); match_and_print(text, pattern); // Matches one or more characters split by space pattern_text = "[a-zA-Z]+"; std::cout << "words without symbols and digits (" << pattern_text << "):\n"; pattern = std::regex(pattern_text); match_and_print(text, pattern); // Matches one non digits, non alphabet pattern_text = "[^0-9A-Za-z]"; std::cout << "symbol (" << pattern_text << "):\n"; pattern = std::regex(pattern_text); match_and_print(text, pattern); // Matches one or more lowercase pattern_text = "[a-z]+"; std::cout << "lowercase (" << pattern_text << "):\n"; pattern = std::regex(pattern_text); match_and_print(text, pattern); // Matches one or more lowercase with std::regex::icase flag pattern_text = "[a-z]+"; std::cout << "lowercase with ignore case flag (" << pattern_text << "):\n"; pattern = std::regex(pattern_text, std::regex::icase); match_and_print(text, pattern); // Matches basic POSIX regular expression pattern_text = "[[:digit:]]+"; std::cout << "basic POSIX regex (" << pattern_text << "):\n"; pattern = std::regex(pattern_text, std::regex::basic); match_and_print(text, pattern); // Matches extended POSIX regular expression pattern_text = "[[:digit:]]+"; std::cout << "extended POSIX regex (" << pattern_text << "):\n"; pattern = std::regex(pattern_text, std::regex::extended); match_and_print(text, pattern); } Output: digits (\d+): 1. "12345" words ([^\s]+): 1. "Hello," 2. "World!" 3. "12345" words without symbols and digits ([a-zA-Z]+): 1. "Hello" 2. "World" symbol ([^0-9A-Za-z]): 1. "," 2. " " 3. "!" 4. " " lowercase ([a-z]+): 1. "ello" 2. "orld" lowercase with ignore case flag ([a-z]+): 1. "Hello" 2. "World" basic POSIX regex ([[:digit:]]+): no match found extended POSIX regex ([[:digit:]]+): 1. "12345" http://cppreference.com 2024.06.10 std::basic_...:basic_regex(3)
NAME | Synopsis | Parameters | Type requirements | Exceptions | Example | Output:
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