#include <iostream>
using namespace std;void test01 ()
{string s1;  //默认构造const char * str = "hello world!";string s2(str);cout << "s2 = " << s2 << endl;string s3(s2);cout << "s3 = " << s3 << endl;string s4(10, 'a');cout << "s4 = " << s4 << endl;
}int main ()
{test01();
}

总结：

string的多种构造方式没有可比性，灵活使用即可。