std::regex_search - cppreference.com (original) (raw)

Determines if there is a match between the regular expression e and some subsequence in the target character sequence. The detailed match result is stored in m (if present).

1,2) The target character sequence is represented by the range [first, last).

3,4) The target character sequence is represented by the range [str, str + std::char_traits<CharT>::length(str)).

5,6) The target character sequence is represented by the string s.

1. The target character sequence cannot be represented by a std::string rvalue.

If a match does not exist, the following expressions involving m (if exists) should yield the specified values:

If a match exists, given any integer in (​0, m.size()) as n, the following expressions involving m should yield the specified values for each overload listed below:

[edit] Parameters

[edit] Return value

Returns true if a match exists, false otherwise.

[edit] Notes

In order to examine all matches within the target sequence, std::regex_search may be called in a loop, restarting each time from m[0].second of the previous call. std::regex_iterator offers an easy interface to this iteration.

[edit] Example

#include #include #include #include   int main() { std::string lines[] = {"Roses are #ff0000", "violets are #0000ff", "all of my base are belong to you"};   std::regex color_regex("#([a-f0-9]{2})" "([a-f0-9]{2})" "([a-f0-9]{2})");   // simple match for (const auto& line : lines) std::cout << line << ": " << std::boolalpha << std::regex_search(line, color_regex) << '\n'; std::cout << '\n';   // show contents of marked subexpressions within each match std::smatch color_match; for (const auto& line : lines) if (std::regex_search(line, color_match, color_regex)) { std::cout << "matches for '" << line << "'\n"; std::cout << "Prefix: '" << color_match.prefix() << "'\n"; for (std::size_t i = 0; i < color_match.size(); ++i) std::cout << i << ": " << color_match[i] << '\n'; std::cout << "Suffix: '" << color_match.suffix() << "'\n\n"; }   // repeated search (see also std::regex_iterator) std::string log(R"( Speed: 366 Mass: 35 Speed: 378 Mass: 32 Speed: 400 Mass: 30)"); std::regex r(R"(Speed:\t\d*)"); for (std::smatch sm; regex_search(log, sm, r);) { std::cout << sm.str() << '\n'; log = sm.suffix(); }   // C-style string demo std::cmatch cm; if (std::regex_search("this is a test", cm, std::regex("test"))) std::cout << "\nFound " << cm[0] << " at position " << cm.prefix().length() << '\n'; }

Output:

Roses are #ff0000: true violets are #0000ff: true all of my base are belong to you: false   matches for 'Roses are #ff0000' Prefix: 'Roses are ' 0: #ff0000 1: ff 2: 00 3: 00 Suffix: ''   matches for 'violets are #0000ff' Prefix: 'violets are ' 0: #0000ff 1: 00 2: 00 3: ff Suffix: ''   Speed: 366 Speed: 378 Speed: 400   Found test at position 10

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[edit] See also

| | regular expression object (class template) [edit] | | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | | identifies one regular expression match, including all sub-expression matches (class template) [edit] | | | attempts to match a regular expression to an entire character sequence (function template) [edit] |