fgets, fgets_unlocked—get character string from a file or stream #include <stdio.h>
char *fgets(char *restrict buf, int n, FILE *restrict fp);
#define _GNU_SOURCE
#include <stdio.h>
char *fgets_unlocked(char *restrict buf, int n, FILE *restrict fp);
#include <stdio.h>
char *_fgets_r(struct _reent *ptr, char *restrict buf, int n, FILE *restrict fp);
#include <stdio.h>
char *_fgets_unlocked_r(struct _reent *ptr, char *restrict buf, int n, FILE *restrict fp);
Description
Reads at most n-1 characters from fp until a newline
is found. The characters including to the newline are stored
in buf. The buffer is terminated with a 0.
fgets_unlocked is a non-thread-safe version of fgets.
fgets_unlocked may only safely be used within a scope
protected by flockfile() (or ftrylockfile()) and funlockfile(). This
function may safely be used in a multi-threaded program if and only
if they are called while the invoking thread owns the (FILE *)
object, as is the case after a successful call to the flockfile() or
ftrylockfile() functions. If threads are disabled, then
fgets_unlocked is equivalent to fgets.
The functions _fgets_r and _fgets_unlocked_r are simply
reentrant versions that are passed the additional reentrant structure
pointer argument: ptr.
Returns
fgets returns the buffer passed to it, with the data
filled in. If end of file occurs with some data already
accumulated, the data is returned with no other indication. If
no data are read, NULL is returned instead.
Portability
fgets should replace all uses of gets. Note however
that fgets returns all of the data, while gets removes
the trailing newline (with no indication that it has done so.)
fgets_unlocked is a GNU extension.
Supporting OS subroutines required: close, fstat, isatty,
lseek, read, sbrk, write.