1.clear()与str("")
测试代码
string s1("333.444.555");
string s2("666.777.888");
stringstream ss;
string w1, w2;
ss << s1;
getline(ss, w1, '.');
cout << w1 << " " << ss.str() << endl;
ss.clear(); // ss.str("");
ss << s2;
getline(ss, w2, '.');
cout << w2 << " " << ss.str() << endl;
测试截图
clear()并没有清空string buff
将上述代码中ss.clear()替换为ss.str("");
测试截图
可见string buff被清空了
原因：
str("")的原型和作用
void str (const string& s);
sets s as the contents of the stream, discarding any previous contents. The object preserves its open mode: if this includes ios_base::ate, the writing position is moved to the end of the new sequence.
clear()的原型和作用
void clear (iostate state = goodbit);
Set error state flags
Sets a new value for the stream's internal error state flags.
其实这段代码也是存在问题的，在别的编译器上可能会报错。在【关于stringstream重复使用时的问题2】中。