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  1. #include <iostream>
  2. #include <string>
  3. #include <regex>
  4.  
  5. int main()
  6. {
  7.     // Simple regular expression matching
  8.     std::string fnames[] = {"foo.txt", "bar.txt", "baz.dat", "zoidberg"};
  9.     std::regex txt_regex("[a-z]+\\.txt");
  10.  
  11.     for (const auto &fname : fnames) {
  12.         std::cout << fname << ": " << std::regex_match(fname, txt_regex) << '\n';
  13.     }   
  14.  
  15.     // Extraction of a sub-match
  16.     std::regex base_regex("([a-z]+)\\.txt");
  17.     std::smatch base_match;
  18.  
  19.     for (const auto &fname : fnames) {
  20.         if (std::regex_match(fname, base_match, base_regex)) {
  21.             // The first sub_match is the whole string; the next
  22.             // sub_match is the first parenthesized expression.
  23.             if (base_match.size() == 2) {
  24.                 std::ssub_match base_sub_match = base_match[1];
  25.                 std::string base = base_sub_match.str();
  26.                 std::cout << fname << " has a base of " << base << '\n';
  27.             }
  28.         }
  29.     }
  30.  
  31.     // Extraction of several sub-matches
  32.     std::regex pieces_regex("([a-z]+)\\.([a-z]+)");
  33.     std::smatch pieces_match;
  34.  
  35.     for (const auto &fname : fnames) {
  36.         if (std::regex_match(fname, pieces_match, pieces_regex)) {
  37.             std::cout << fname << '\n';
  38.             for (size_t i = 0; i < pieces_match.size(); ++i) {
  39.                 std::ssub_match sub_match = pieces_match[i];
  40.                 std::string piece = sub_match.str();
  41.                 std::cout << "  submatch " << i << ": " << piece << '\n';
  42.             }   
  43.         }   
  44.     }   
  45. }
Runtime error #stdin #stdout #stderr 0s 3020KB
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stdin
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Standard input is empty
stdout
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Standard output is empty
stderr
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terminate called after throwing an instance of 'std::regex_error'
  what():  regex_error
https://ideone.com/Pq9XUj
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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