length.md

length

• regex[meta header]
• std[meta namespace]
• sub_match[meta class]
• function[meta id-type]
• cpp11[meta cpp]

difference_type length() const;

概要

マッチした文字列の長さを返す。

戻り値

matched ? distance(first, second) : 0

例

#include <iostream>
#include <regex>
#include <string>

int main()
{
  const std::string s("123");
  const std::regex re(R"(\d+)");
  std::smatch m;
  if (std::regex_search(s, m, re)) {
    std::ssub_match sub = m[0];
    if (sub.matched) {
      std::cout << sub.length() << std::endl;
      sub.matched = false;
      std::cout << sub.length() << std::endl;
    } else {
      std::cout << "not participate" << std::endl;
    }
  } else {
    std::cout << "not match" << std::endl;
  }
}

• length()[color ff0000]
• std::regex[link ../basic_regex.md]
• std::smatch[link ../match_results.md]
• std::regex_search[link ../regex_search.md]
• std::ssub_match[link ../sub_match.md]

出力

3
0

バージョン

言語

• C++11

処理系

• Clang: 3.0 [mark verified], 3.1 [mark verified], 3.2 [mark verified], 3.3 [mark verified], 3.4 [mark verified], 3.5 [mark verified], 3.6 [mark verified]
• GCC: 4.9.0 [mark verified], 4.9.1 [mark verified], 5.0.0 [mark verified]
• ICC: ??
• Visual C++: ??