FTELL(3)                   POSIX Programmer's Manual                  FTELL(3)



PPRROOLLOOGG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

NNAAMMEE
       ftell, ftello -- return a file offset in a stream

SSYYNNOOPPSSIISS
       #include <stdio.h>

       long ftell(FILE *_s_t_r_e_a_m);
       off_t ftello(FILE *_s_t_r_e_a_m);

DDEESSCCRRIIPPTTIIOONN
       The functionality described on this reference page is aligned with the
       ISO C standard. Any conflict between the requirements described here
       and the ISO C standard is unintentional. This volume of POSIX.1-2017
       defers to the ISO C standard.

       The _f_t_e_l_l() function shall obtain the current value of the file-
       position indicator for the stream pointed to by _s_t_r_e_a_m.

       The _f_t_e_l_l() function shall not change the setting of _e_r_r_n_o if
       successful.

       The _f_t_e_l_l_o() function shall be equivalent to _f_t_e_l_l(), except that the
       return value is of type ooffff__tt and the _f_t_e_l_l_o() function may change the
       setting of _e_r_r_n_o if successful.

RREETTUURRNN VVAALLUUEE
       Upon successful completion, _f_t_e_l_l() and _f_t_e_l_l_o() shall return the
       current value of the file-position indicator for the stream measured in
       bytes from the beginning of the file.

       Otherwise, _f_t_e_l_l() and _f_t_e_l_l_o() shall return -1, and set _e_r_r_n_o to
       indicate the error.

EERRRROORRSS
       The _f_t_e_l_l() and _f_t_e_l_l_o() functions shall fail if:

       EEBBAADDFF  The file descriptor underlying _s_t_r_e_a_m is not an open file
              descriptor.

       EEOOVVEERRFFLLOOWW
              For _f_t_e_l_l(), the current file offset cannot be represented
              correctly in an object of type lloonngg.

       EEOOVVEERRFFLLOOWW
              For _f_t_e_l_l_o(), the current file offset cannot be represented
              correctly in an object of type ooffff__tt.

       EESSPPIIPPEE The file descriptor underlying _s_t_r_e_a_m is associated with a pipe,
              FIFO, or socket.

       _T_h_e _f_o_l_l_o_w_i_n_g _s_e_c_t_i_o_n_s _a_r_e _i_n_f_o_r_m_a_t_i_v_e_.

EEXXAAMMPPLLEESS
       None.

AAPPPPLLIICCAATTIIOONN UUSSAAGGEE
       None.

RRAATTIIOONNAALLEE
       None.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _S_e_c_t_i_o_n _2_._5, _S_t_a_n_d_a_r_d _I_/_O _S_t_r_e_a_m_s, _f_g_e_t_p_o_s(), _f_o_p_e_n(), _f_s_e_e_k(), _l_s_e_e_k()

       The Base Definitions volume of POSIX.1-2017, <<ssttddiioo..hh>>

CCOOPPYYRRIIGGHHTT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  In the event of any discrepancy between this version and the
       original IEEE and The Open Group Standard, the original IEEE and The
       Open Group Standard is the referee document. The original Standard can
       be obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017                             FTELL(3)
