Ifn>0 andn< size(), returns a reference to thestd::sub_match representing the part of the target sequence that was matched by then^th capturedmarked subexpression).

Ifn==0, returns a reference to thestd::sub_match representing the part of the target sequence matched by the entire matched regular expression.

ifn>= size(), returns a reference to astd::sub_match representing an unmatched sub-expression (an empty subrange of the target sequence).

ready() must betrue. Otherwise, the behavior is undefined.

[edit]Parameters

[edit]Return value

Reference to thestd::sub_match representing the specified matched subrange within the target sequence.

[edit]Example

#include <iostream>#include <regex>#include <string> int main(){std::string target("baaaby");std::smatch sm; std::regex re1("a(a)*b");std::regex_search(target, sm, re1);std::cout<<"entire match: "<< sm[0]<<'\n'<<"submatch #1: "<< sm[1]<<'\n'; std::regex re2("a(a*)b");std::regex_search(target, sm, re2);std::cout<<"entire match: "<< sm[0]<<'\n'<<"submatch #1: "<< sm[1]<<'\n';}

entire match: aaabsubmatch #1: aentire match: aaabsubmatch #1: aa

[edit]See also

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