C++中string类的七个构造函数用法用例

这是从C++primer plus这本书上整理出来的，很有用。

//测试string的七个构造函数string one("Lottery Winner");cout<<one<<endl;string two(20,'$');//20个元素的string对象，每个元素初始为$cout<<two<<endl;string three(one);//复制构造函数cout<<three<<endl;one+=" Oops!";//overload +=cout<<one<<endl;two="Sorry! That was ";three[0]='p';string four;four=two+three;//overload + =cout<<four<<endl;char alls[]="All`s well that ends well";string five(alls,20);//将five初始化为alls的前20个字符，即使超过了alls结尾也没事cout<<five<<endl;string six(alls+6,alls+10);//将six初始化alls的[6,10)之间的字符，6包含，10不包含。注：这是下标cout<<six<<", ";string seven(&five[6],&five[10]);//同sixcout<<seven<<"...\n";string eight(four,7,16); //将eight初始化为four中，从位置7(下标)开始的16个字符，或者结尾;cout<<eight<<" in motion!"<<endl;