【C++】string类的使用③（修改器Modifiers || 非成员函数重载Non-member function overloads）

🔥个人主页： Forcible Bug Maker

🔥专栏： STL || C++

目录

• 前言
• 🔥修改器（Modifiers）
• • ==**operator+=**==
  • ==append==
  • ==push_back和pop_back==
  • ==assign==
  • ==insert==
  • ==erase==
  • ==replace==
  • ==swap==
  • 🔥非成员函数重载（Non-member function overloads）
  • • ==operator+==
    • ==relation operators(string)==
    • ==swap(string)==
    • ==流插入和流提取重载==
    • ==getline==
    • 结语

      前言

      本篇博客主要内容：STL库中string的修改器（Modifiers）和非成员函数重载（Non-member function overloads）。

      来到string类的使用第三篇，继续我们的内容，本篇博客将介绍如何使用STL库中string的成员函数修改串，以及重载给string的几个非成员函数。

      🔥修改器（Modifiers）

      

      顾名思义，就是一批能改动string串中内容的成员函数。

      operator+=

      这是一个成员函数的运算符重载。

      

      简单说就是在串的末尾追加字符或字符串。

      (1) string string对象

      string& operator+= (const string& str);

      (2) c-string 字符串指针

      string& operator+= (const char* s);

      (3) character 字符

      string& operator+= (char c);

      以上三个重载的功能用一句话概括：在当前string串的末尾追加字符或字符串。

      共同的返回值：当前对象的引用（string&）。

      使用样例：

      // string::operator+=
      #include 
      #include 
      using namespace std;
      int main()
      {
      	string name("John");
      	string family("Smith");
      	name += " K. ";         // c-string
      	name += family;         // string
      	name += '\n';           // character
      	cout 
      	string str;
      	string str2 = "Writing ";
      	string str3 = "print 10 and then 5 more";
      	// used in the same order as described above:
      	str.append(str2);                       // "Writing "
      	str.append(str3, 6, 3);                   // "10 "
      	str.append("dots are cool", 5);          // "dots "
      	str.append("here: ");                   // "here: "
      	str.append(10, '.');                    // ".........."
      	str.append(str3.begin() + 8, str3.end());  // " and then 5 more"
      	cout 
      	string str("Hello World");
      	str.push_back('!');
      	cout 
      	string str;
      	string base = "The quick brown fox jumps over a lazy dog.";
      	// used in the same order as described above:
      	str.assign(base);
      	cout 
      	string str = "to be question";
      	string str2 = "the ";
      	string str3 = "or not to be";
      	string::iterator it;
      	// used in the same order as described above:
      	str.insert(6, str2);                 // to be (the )question
      	str.insert(6, str3, 3, 4);             // to be (not )the question
      	str.insert(10, "that is cool", 8);    // to be not (that is )the question
      	str.insert(10, "to be ");            // to be not (to be )that is the question
      	str.insert(15, 1, ':');               // to be not to be(:) that is the question
      	it = str.insert(str.begin() + 5, ','); // to be(,) not to be: that is the question
      	str.insert(str.end(), 3, '.');       // to be, not to be: that is the question(...)
      	str.insert(it + 2, str3.begin(), str3.begin() + 3); // (or )
      	cout 
          std::string str("This is an example sentence.");
          cout 
      	string base = "this is a test string.";
      	string str2 = "n example";
      	string str3 = "sample phrase";
      	string str4 = "useful.";
      	// replace signatures used in the same order as described above:
      	// Using positions:                 0123456789*123456789*12345
      	string str = base;           // "this is a test string."
      	str.replace(9, 5, str2);          // "this is an example string." (1)
      	str.replace(19, 6, str3, 7, 6);     // "this is an example phrase." (2)
      	str.replace(8, 10, "just a");     // "this is just a phrase."     (3)
      	str.replace(8, 6, "a shorty", 7);  // "this is a short phrase."    (4)
      	str.replace(22, 1, 3, '!');        // "this is a short phrase!!!"  (5)
      	// Using iterators:0123456789*123456789*
      	str.replace(str.begin(), str.end() - 3, str3);                    // "sample phrase!!!"      (1)
      	str.replace(str.begin(), str.begin() + 6, "replace");             // "replace phrase!!!"     (3)
      	str.replace(str.begin() + 8, str.begin() + 14, "is coolness", 7);    // "replace is cool!!!"    (4)
      	str.replace(str.begin() + 12, str.end() - 4, 4, 'o');                // "replace is cooool!!!"  (5)
      	str.replace(str.begin() + 11, str.end(), str4.begin(), str4.end());// "replace is useful."    (6)
      	cout 
      	string str1("hello");
      	string str2("world");
      	cout 
      	string firstlevel("com");
      	string secondlevel("cplusplus");
      	string scheme("http://");
      	string hostname;
      	string url;
      	hostname = "www." + secondlevel + '.' + firstlevel;
      	url = scheme + hostname;
      	cout 
      	string foo = "alpha";
      	string bar = "beta";
      	if (foo == bar) cout 
      	string str1("hello");
      	string str2("world");
      	cout 
      	string str;
      	cin  str;
      	cout 
      	string name;
      	cout