NAME fseek, rewind, ftell - reposition a file pointer in a stream SYNTAX #include int fseek (stream, offset, ptrname) FILE *stream; long offset; int ptrname; void rewind (stream) FILE *stream; long ftell (stream) FILE *stream; DESCRIPTION Fseek sets the position of the next input or output operation on the stream. The new position is at the signed distance offset bytes from the beginning, from the current position, or from the end of the file, according as ptrname has the value 0, 1, or 2. Rewind(stream) is equivalent to fseek(stream, 0L, 0), except that no value is returned. Fseek and rewind undo any effects of ungetc(3S). After fseek or rewind, the next operation on a file opened for update may be either input or output. Ftell returns the offset of the current byte relative to the beginning of the file associated with the named stream. SEE ALSO lseek(2), fopen(3S), popen(3S), ungetc(3S). DIAGNOSTICS Fseek returns non-zero for improper seeks, otherwise zero. An improper seek can be, for example, an fseek done on a file that has not been opened via fopen; in particular, fseek may not be used on a terminal, or on a file opened via popen(3S). WARNING Although on the UNIX system an offset returned by ftell is measured in bytes, and it is permissible to seek to positions relative to that offset, portability to non-UNIX systems requires that an offset be used by fseek directly. Arithmetic may not meaningfully be performed on such an offset, which is not necessarily measured in bytes.