怎样重新回到文件的开头？解决办法

怎样重新回到文件的开头？
有以下代码:
string   iName;
cin   > >   iName;
fstream   file   (   iName.c_str()   );  
if   (   !file   )
{
cout   < <   "open   infile   failed! ";
exit   (   -1   );
}


当文件读取到一定位置，怎样重新回到文件的开头呢？

------解决方案--------------------
// basic_istream_seekg.cpp
// compile with: /EHsc
#include <iostream>
#include <fstream>

int main ( )
{
using namespace std;
ifstream file;
char c, c1;

file.open( "basic_istream_seekg.txt " );
file.seekg(2); // chars to skip
file > > c;
cout < < c < < endl;

file.seekg( 0, ios_base::beg );
file > > c;
cout < < c < < endl;

file.seekg( -1, ios_base::end );
file > > c1;
cout < < c1 < < endl;
}
------解决方案--------------------
ifstream ifs( "test.cpp " );
string str;
getline( ifs , str);
cout < <str < <endl;
ifs.seekg(0);//这样就可以了
getline( ifs , str);
cout < <str < <endl;