/*
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/*
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FUNCTION
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FUNCTION
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<<fgetpos>>---record position in a stream or file
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<<fgetpos>>---record position in a stream or file
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INDEX
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INDEX
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fgetpos
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fgetpos
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ANSI_SYNOPSIS
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ANSI_SYNOPSIS
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#include <stdio.h>
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#include <stdio.h>
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int fgetpos(FILE *<[fp]>, fpos_t *<[pos]>);
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int fgetpos(FILE *<[fp]>, fpos_t *<[pos]>);
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TRAD_SYNOPSIS
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TRAD_SYNOPSIS
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#include <stdio.h>
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#include <stdio.h>
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int fgetpos(<[fp]>, <[pos]>)
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int fgetpos(<[fp]>, <[pos]>)
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FILE *<[fp]>;
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FILE *<[fp]>;
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fpos_t *<[pos]>;
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fpos_t *<[pos]>;
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DESCRIPTION
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DESCRIPTION
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Objects of type <<FILE>> can have a ``position'' that records how much
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Objects of type <<FILE>> can have a ``position'' that records how much
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of the file your program has already read. Many of the <<stdio>> functions
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of the file your program has already read. Many of the <<stdio>> functions
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depend on this position, and many change it as a side effect.
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depend on this position, and many change it as a side effect.
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You can use <<fgetpos>> to report on the current position for a file
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You can use <<fgetpos>> to report on the current position for a file
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identified by <[fp]>; <<fgetpos>> will write a value
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identified by <[fp]>; <<fgetpos>> will write a value
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representing that position at <<*<[pos]>>>. Later, you can
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representing that position at <<*<[pos]>>>. Later, you can
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use this value with <<fsetpos>> to return the file to this
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use this value with <<fsetpos>> to return the file to this
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position.
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position.
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In the current implementation, <<fgetpos>> simply uses a character
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In the current implementation, <<fgetpos>> simply uses a character
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count to represent the file position; this is the same number that
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count to represent the file position; this is the same number that
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would be returned by <<ftell>>.
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would be returned by <<ftell>>.
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RETURNS
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RETURNS
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<<fgetpos>> returns <<0>> when successful. If <<fgetpos>> fails, the
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<<fgetpos>> returns <<0>> when successful. If <<fgetpos>> fails, the
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result is <<1>>. Failure occurs on streams that do not support
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result is <<1>>. Failure occurs on streams that do not support
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positioning; the global <<errno>> indicates this condition with the
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positioning; the global <<errno>> indicates this condition with the
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value <<ESPIPE>>.
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value <<ESPIPE>>.
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PORTABILITY
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PORTABILITY
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<<fgetpos>> is required by the ANSI C standard, but the meaning of the
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<<fgetpos>> is required by the ANSI C standard, but the meaning of the
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value it records is not specified beyond requiring that it be
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value it records is not specified beyond requiring that it be
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acceptable as an argument to <<fsetpos>>. In particular, other
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acceptable as an argument to <<fsetpos>>. In particular, other
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conforming C implementations may return a different result from
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conforming C implementations may return a different result from
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<<ftell>> than what <<fgetpos>> writes at <<*<[pos]>>>.
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<<ftell>> than what <<fgetpos>> writes at <<*<[pos]>>>.
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No supporting OS subroutines are required.
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No supporting OS subroutines are required.
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*/
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*/
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#include <stdio.h>
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#include <stdio.h>
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int
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int
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_DEFUN (fgetpos, (fp, pos),
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_DEFUN (fgetpos, (fp, pos),
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FILE * fp _AND
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FILE * fp _AND
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fpos_t * pos)
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fpos_t * pos)
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{
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{
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*pos = ftell (fp);
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*pos = ftell (fp);
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if (*pos != -1)
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if (*pos != -1)
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return 0;
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return 0;
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return 1;
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return 1;
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}
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}
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