| .\" Copyright 2001 Andries Brouwer <aeb@cwi.nl>. |
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| .TH FSEEKO 3 2021-03-22 "" "Linux Programmer's Manual" |
| .SH NAME |
| fseeko, ftello \- seek to or report file position |
| .SH SYNOPSIS |
| .nf |
| .B #include <stdio.h> |
| .PP |
| .BI "int fseeko(FILE *" stream ", off_t " offset ", int " whence ); |
| .BI "off_t ftello(FILE *" stream ); |
| .fi |
| .PP |
| .RS -4 |
| Feature Test Macro Requirements for glibc (see |
| .BR feature_test_macros (7)): |
| .RE |
| .PP |
| .BR fseeko (), |
| .BR ftello (): |
| .nf |
| _FILE_OFFSET_BITS == 64 || _POSIX_C_SOURCE >= 200112L |
| .fi |
| .SH DESCRIPTION |
| The |
| .BR fseeko () |
| and |
| .BR ftello () |
| functions are identical to |
| .BR fseek (3) |
| and |
| .BR ftell (3) |
| (see |
| .BR fseek (3)), |
| respectively, except that the |
| .I offset |
| argument of |
| .BR fseeko () |
| and the return value of |
| .BR ftello () |
| is of type |
| .I off_t |
| instead of |
| .IR long . |
| .PP |
| On some architectures, both |
| .IR off_t |
| and |
| .I long |
| are 32-bit types, but defining |
| .BR _FILE_OFFSET_BITS |
| with the value 64 (before including |
| .I any |
| header files) |
| will turn |
| .I off_t |
| into a 64-bit type. |
| .SH RETURN VALUE |
| On successful completion, |
| .BR fseeko () |
| returns 0, while |
| .BR ftello () |
| returns the current offset. |
| Otherwise, \-1 is returned and |
| .I errno |
| is set to indicate the error. |
| .SH ERRORS |
| See the ERRORS in |
| .BR fseek (3). |
| .SH VERSIONS |
| These functions are available under glibc since version 2.1. |
| .SH ATTRIBUTES |
| For an explanation of the terms used in this section, see |
| .BR attributes (7). |
| .ad l |
| .nh |
| .TS |
| allbox; |
| lbx lb lb |
| l l l. |
| Interface Attribute Value |
| T{ |
| .BR fseeko (), |
| .BR ftello () |
| T} Thread safety MT-Safe |
| .TE |
| .hy |
| .ad |
| .sp 1 |
| .SH CONFORMING TO |
| POSIX.1-2001, POSIX.1-2008, SUSv2. |
| .SH NOTES |
| The declarations of these functions can also be obtained by defining |
| the obsolete |
| .B _LARGEFILE_SOURCE |
| feature test macro. |
| .SH SEE ALSO |
| .BR fseek (3) |