How to read previous line of file?

Ok, so I was wondering how would I read a previous line of a file I already read with getline(ifstream_object, buffer_str)?
I figured seekg(-1, ios_base::cur) might work to step to the position of the previous line, but since I don't have much experience using seekg() and the reference that I read on it didn't mention how the first parameter "streampos off" is calculated (i.e. if its relative to the line read or if its relative to the character position), I figured I would ask here.

The easiest way would be to store the previous line as you step through, i.e. read in the current line, and at the end of your loop store curr -> last

Obviously it's relative to the current character position, not line.

Saving the line as Epy suggests is the simplest thing.

Or you could do -> istream::tellg - C++ Reference

Code:

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streampos pos = fs.tellg();
// read a line
...
fs.seekg(pos, ios::beg);
// read a line again.

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