16.1.1 构造字符串
程序清单16.1使用了string的7个构造函数。
程序清单16.1 str1.cpp
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// str1.cpp -- introducing the string class
#include <iostream>
#include <string>
// using string constructors
int main()
{
using namespace std;
string one("Lottery Winner!"); // ctor #1
cout << one << endl; // overloaded <<
string two(20, '$'); // ctor #2
cout << two << endl;
string three(one); // ctor #3
cout << three << endl;
one += " Oops!";
cout << one << endl;
two = "Sorry! That was ";
three[0] = 'P';
string four; // ctor #4
four = two + three; // overloaded +, =
cout << four << endl;
char alls[] = "All's well that ends well";
string five(alls, 20); // ctor #5
cout << five << "!
";
string six(alls+6, alls + 10); // ctor #6
cout << six << endl;
string seven(&five[6], &five[10]); // cotr #6
cout << seven << "...
";
string eight(four, 7, 16);
cout << eight << " in motion!" << endl;
return 0;
}
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效果：
Lottery Winner!
$$$$$$$$$$$$$$$$$$$$
Lottery Winner!
Lottery Winner! Oops!
Sorry! That was Pottery Winner!
All's well that ends!
well
well...
That was Pottery in motion!
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构造函数string(initializer_list<char> il)让您能够将列表初始化语法用于string类。也就是说，它使得下面这样的生命是合法的：
string piano_man = {'L', 'i', 's', 'z', 't'};
string comp_lang {'L', 'i', 's', 'p'};
16.1.2 string类输入
对于C-风格字符串，输入有3种方式：
char info[100];
cin >> info; // read a word
cin.getline(info, 100); // read a line, discard
cin.get(info, 100); // read a line, leave
in queue
对于string对象，有两种方式：
string stuff;
cin >> stuff; // read a word
getline(cin, stuff); // read a line, discard
两个版本的getline()都有一个可选参数，用于指定使用哪个字符来确定输入的边界：
cin.getline(info, 100, ':'); // read up to :, discard :
getline(stuff, ':'); // read up to :, discard :
在功能上，C-风格字符串和string的主要区别在于，string版本的getline()将自动调整目标string对象的大小，使之刚好能够存储输入的字符。
16.1.3 使用字符串
……
16.1.4 string还提供了哪些功能
……
16.1.5 字符串种类
本节将string类看作基于char类型的。事实上，正如前面指出的，string库实际上是基于一个模板类的：
template<class charT, class traits = char, traits<charT>,
class Allocator = allocator<charT> >
basic_string {...};
模板basic_string有4个具体化，每个具体化都有一个typedef名称：
typedef basic_string<char> string;
typedef basic_string<wchar_t> wstring;
typedef basic_string<char16_t> u16string; // C++11
typedef basic_string<char32_t> u32string; // C++11
这让您能够使用基于类型wchar_t、wchar16_t、char32_t和char的字符串。