How can I take data from fstream and then take it again?

Question

I'm a begginer at c++, so I wanted to ask, how can I take data from fstream after I already took all the data from it?

I have done something like this

fstream file;
string data, key, key2;
while(file>>data)
{
    key += data;
}

Now I want to do it again with the same file but without re-open it:

while(file>>data)
{
    key2 += data;
}

How can I do that with fstream?

Answer 1

Rewind the stream:

file.clear();
file.seekg(0);