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Asked: 2026-05-30T01:28:02+00:00

I was asked by an interviewer that how would I implement tail (yes, the

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I was asked by an interviewer that how would I implement tail (yes, the one in linux shell). My answer was, first seek to the end of the file, then read characters one-by-one forward, if encounters a \n, means one line is down, blah blah blah. I assume my answer is correct.

Then I found this problem, which seek should I use to implement tail? I thought I can simply use seekg (C++ thing?), but I was told that I should use lseek (linux system call?).

So including fseek (ANSI C thing?), which one should I use to implement tail?
And is there any big difference between them?

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1 Answer

  1. Editorial Team

    Use seekg when using the C++ IOstreams library. seekp is no use here, since it sets the put pointer.

    Use fseek when using the C stdio library. Use lseek when using low-level POSIX file descriptor I/O.

    The difference between the various seek functions is just the kind of file/stream objects on which they operate. On Linux, seekg and fseek are probably implemented in terms of lseek.

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