C++ Regex Library - regex_search

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Description

It returns whether some sub-sequence in the target sequence (the subject) matches the regular expression rgx (the pattern). The target sequence is either s or the character sequence between first and last, depending on the version used.

Declaration

Following is the declaration for std::regex_search.

 template <class charT, class traits> bool regex_search (const charT* s, const basic_regex<charT,traits>& rgx, regex_constants::match_flag_type flags = regex_constants::match_default); 

C++11

 template <class charT, class traits> bool regex_search (const charT* s, const basic_regex<charT,traits>& rgx, regex_constants::match_flag_type flags = regex_constants::match_default); 

C++14

 template <class charT, class traits> bool regex_search (const charT* s, const basic_regex<charT,traits>& rgx, regex_constants::match_flag_type flags = regex_constants::match_default); 

Parameters

• s − It is a string with the target sequence.

• rgx − It is a basic_regex object to match.

• flags − It is used to control how rgx is matched.

• m − It is an object of a match_results type.

Return Value

It returns true if rgx matches against a sub-sequence in the target sequence. false otherwise.

Exceptions

No-noexcept − this member function never throws exceptions.

Example

In below example for std::regex_search.

 #include <iostream> #include <string> #include <regex> int main () { std::string s ("this subject has a submarine as a subsequence"); std::smatch m; std::regex e ("\\b(sub)([^ ]*)"); std::cout << "Target sequence: " << s << std::endl; std::cout << "Regular expression: /\\b(sub)([^ ]*)/" << std::endl; std::cout << "The following matches and submatches were found:" << std::endl; while (std::regex_search (s,m,e)) { for (auto x:m) std::cout << x << " "; std::cout << std::endl; s = m.suffix().str(); } return 0; } 

The output should be like this −

 Target sequence: this subject has a submarine as a subsequence Regular expression: /\b(sub)([^ ]*)/ The following matches and submatches were found: subject sub ject submarine sub marine subsequence sub sequence