Resetting ifstream

[hopesfall]

I'm reading lines of text from a file and I need to loop through the entire file twice but I can't figure out how to do it...I have this so far:

int main(){
   ifstream dictFile(filename.c_str());
   HashDictionary websta(dictFile);
}

HashDictionary::HashDictionary(istream &sin){
	while(!sin.eof()){
		//... do stuff with the lines being read
	}

        // now I want to loop through the file again here but sin.eof() 
        // is already false by this point from the previous loop
	while(!sin.eof()){
		// do stuff
	}

[shacktar]

while(!sin.eof()){
     //... do stuff with the lines being read
}

sin.clear(); //clear error flags
sin.seekg(0, std::ios::beg); //set the file get pointer back to the beginning

while(!sin.eof()){
     // do stuff
}

[JLBorges]

HashDictionary::HashDictionary(istream &sin){
	while(!sin.eof()){
		//... do stuff with the lines being read
	}

        // now I want to loop through the file again here but sin.eof() 
        // is already false by this point from the previous loop

        sin.clear() ; // clear the failed eof state **** 
        sin.seekg(0) ; // rewind the stream to the beginning ****

	while(!sin.eof()){
		// do stuff
	}

This is a construct that can introduce a subtle logical error:

while(!sin.eof()){
		// do stuff
	}

Instead prefer doing something like:

while( sin >> key >> data ){
		// do stuff
	}