op_plus.md

operator+

• string[meta header]
• std[meta namespace]
• function template[meta id-type]

template <class charT, class traits, class Allocator>
basic_string<charT, traits, Allocator>
  operator+(const basic_string<charT, traits, Allocator>& lhs,
            const basic_string<charT, traits, Allocator>& rhs); // (1)

template <class charT, class traits, class Allocator>
basic_string<charT, traits, Allocator>
  operator+(basic_string<charT, traits, Allocator>&& lhs,
            const basic_string<charT, traits, Allocator>& rhs); // (2) C++11 から

template <class charT, class traits, class Allocator>
basic_string<charT, traits, Allocator>
  operator+(const basic_string<charT, traits, Allocator>& lhs,
            basic_string<charT, traits, Allocator>&& rhs);      // (3) C++11 から

template <class charT, class traits, class Allocator>
basic_string<charT, traits, Allocator>
  operator+(basic_string<charT, traits, Allocator>&& lhs,
            basic_string<charT, traits, Allocator>&& rhs);      // (4) C++11 から

template <class charT, class traits, class Allocator>
basic_string<charT, traits, Allocator>
  operator+(const charT* lhs,
            const basic_string<charT, traits, Allocator>& rhs); // (5)

template <class charT, class traits, class Allocator>
basic_string<charT, traits, Allocator>
  operator+(const charT* lhs,
            basic_string<charT, traits, Allocator>&& rhs);      // (6) C++11 から

template <class charT, class traits, class Allocator>
basic_string<charT, traits, Allocator>
  operator+(charT lhs,
            const basic_string<charT, traits, Allocator>& rhs); // (7)

template <class charT, class traits, class Allocator>
basic_string<charT, traits, Allocator>
  operator+(charT lhs,
            basic_string<charT, traits, Allocator>&& rhs);      // (8) C++11 から

template <class charT, class traits, class Allocator>
basic_string<charT, traits, Allocator>
  operator+(const basic_string<charT, traits, Allocator>& rhs,
            const charT* lhs);                                  // (9)

template <class charT, class traits, class Allocator>
basic_string<charT, traits, Allocator>
  operator+(basic_string<charT, traits, Allocator>&& rhs,
            const charT* lhs);                                  // (10) C++11 から

template <class charT, class traits, class Allocator>
basic_string<charT, traits, Allocator>
  operator+(const basic_string<charT, traits, Allocator>& rhs,
            charT lhs);                                         // (11)

template <class charT, class traits, class Allocator>
basic_string<charT, traits, Allocator>
  operator+(basic_string<charT, traits, Allocator>&& rhs,
            charT lhs);                                         // (12) C++11 から

概要

basic_string オブジェクトの連結を行う。

戻り値

• (1) basic_string<charT, traits, Allocator>(lhs).append(rhs)

• (2) std::move(lhs.append(rhs))

• (3) std::move(rhs.insert(0, lhs))

• (4) std::move(lhs.append(rhs))
  (std::move(rhs.insert(0, lhs)) とも等価)

• (5) basic_string<charT, traits, Allocator>(lhs) + rhs

• (6) std::move(rhs.insert(0, lhs))

• (7) basic_string<charT, traits, Allocator>(1, lhs) + rhs

• (8) std::move(rhs.insert(0, 1, lhs))

• (9) lhs + basic_string<charT, traits, Allocator>(rhs)

• (10) std::move(lhs.append(rhs))

• (11) lhs + basic_string<charT, traits, Allocator>(1, rhs)

• (12) std::move(lhs.append(1, rhs))

備考

(5)、(6) の形式の lhs、および、(9)、(10) の形式の rhs の文字列長算出のために traits::length() が使用される

例

#include <iostream>
#include <string>

int main()
{
  std::string s1("Hell");
  std::string s2("world");

  std::string s3 = s1 + 'o' + ", " + s2 + '!';

  std::cout << s3 << '\n';
}

• +[color ff0000]

出力

Hello, world!

関連項目

名前	説明
append	文字／文字列を追加する
push_back	文字を追加する
insert	文字／文字列を挿入する