Low-level I/O
These functions invoke the operating system directly for lower-level operation than that provided by stream I/O. Low-level input and output calls don't buffer or format data.
Low-level routines can access the standard streams opened at program startup using the following predefined file descriptors.
Stream | File Descriptor |
---|---|
stdin |
0 |
stdout |
1 |
stderr |
2 |
Low-level I/O routines set the errno
global variable when an error occurs. You must include STDIO.H
when you use low-level functions only if your program requires a constant that is defined in STDIO.H
, such as the end-of-file indicator (EOF
).
Low-level I/O functions
Function | Use |
---|---|
_close |
Close file |
_commit |
Flush file to disk |
_creat , _wcreat |
Create file |
_dup |
Return next available file descriptor for given file |
_dup2 |
Create second descriptor for given file |
_eof |
Test for end of file |
_lseek , _lseeki64 |
Reposition file pointer to given location |
_open , _wopen |
Open file |
_read |
Read data from file |
_sopen , _wsopen , _sopen_s , _wsopen_s |
Open file for file sharing |
_tell , _telli64 |
Get current file-pointer position |
_umask , _umask_s |
Set file-permission mask |
_write |
Write data to file |
_dup
and _dup2
are typically used to associate the predefined file descriptors with different files.
See also
Input and output
Universal C runtime routines by category
System calls
Σχόλια
https://aka.ms/ContentUserFeedback.
Σύντομα διαθέσιμα: Καθ' όλη τη διάρκεια του 2024 θα καταργήσουμε σταδιακά τα ζητήματα GitHub ως μηχανισμό ανάδρασης για το περιεχόμενο και θα το αντικαταστήσουμε με ένα νέο σύστημα ανάδρασης. Για περισσότερες πληροφορίες, ανατρέξτε στο θέμα:Υποβολή και προβολή σχολίων για