string末尾有'\0'吗?

#include <iostream>
#include <string>
using namespace std;
int main()
{
string s = "abc";
/*for (int i=0;i!=s.size();++i)
{
cout << s[i];
}*/
/*for (int i=0;i<s.size();++i)
{
cout << s[i];
}*/
/*for (int i=0;s[i]!='\0';++i)
{
cout << s[i];
}*/
for (auto x:s)
{
cout << x;
}
return 0;
}

 //以上程序运行结果一致