像下面这样改就行了

程序代码:
string fn = "ReadMe.txt";
ifstream fin(fn.c_str(), ios_base::in);
if(!fin.is_open())
{
cerr<<"can't open "<<fn<<endl;
exit(EXIT_FAILURE);
}
char buf[1024];
int readSize = 0;
while (!fin.eof())
{
memset(buf, 0, sizeof(buf));
fin.getline(buf, sizeof(buf));
cout << buf << endl;
}
fin.close();