For streams opened in text mode, fseek and _fseeki64 have limited use, because carriage return-linefeed translations can cause fseek and _fseeki64 to produce unexpected results. The only fseek and _fseeki64 operations guaranteed to work on streams opened in text mode are:
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Seeking with an offset of 0 relative to any of the origin values.
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Seeking from the beginning of the file with an offset value returned from a call to ftell when using fseek or _ftelli64 when using _fseeki64.
https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/fseek-fseeki64?view=vs-2017