NAME
fgets — get a
string from a stream
SYNOPSIS
#include
<stdio.h>
char *fgets(char *restrict s, int n, FILE *restrict stream);
DESCRIPTION
[CX] 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.1-2008 defers to the ISO C standard.
The fgets () function shall read
bytes from stream into the array pointed to by
s, until
n -1 bytes are read, or
a <newline> is read and transferred to s, or an
end-of-file condition is encountered. The string is then terminated with a
null byte.
[CX] The fgets ()
function may mark the last data access timestamp of the file associated with
stream for update. The last data access timestamp shall be
marked for update by the first successful execution of
fgetc(3), fgets (),
fread(3), fscanf(3),
getc(3), getchar(3),
getdelim(3), getline(3),
gets(3), or scanf(3) using
stream that returns data not supplied by a prior call to
ungetc(3).
RETURN VALUE
Upon successful completion, fgets () shall
return s. If the stream is at end-of-file, the end-of-file
indicator for the stream shall be set and fgets ()
shall return a null pointer. If a read error occurs, the error indicator for
the stream shall be set, fgets () shall return a
null pointer, [CX] and shall set
errno to
indicate the error.
ERRORS
Refer to fgetc(3) .
EXAMPLES
Reading Input
The following example uses fgets () to
read each line of input. {LINE_MAX}, which defines the maximum size of the
input line, is defined in the <limits.h>
header.
#include <stdio.h>
...
char line[LINE_MAX];
...
while (fgets(line, LINE_MAX, fp) != NULL) {
...
}
...
APPLICATION USAGE
None.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
fgetc(3) , fopen(3) , fread(3) , fscanf(3) , getc(3) , getchar(3) , getdelim(3) , gets(3) , ungetc(3)
XBD <stdio.h>
CHANGE HISTORY
First released in Issue 1. Derived from Issue 1 of the SVID.
Issue 6
Extensions beyond the ISO C standard are marked.
The prototype for fgets () is changed for
alignment with the ISO/IEC 9899:1999
(“ISO C99”) standard.
Issue 7
Austin Group Interpretation 1003.1-2001 #051 is applied, updating the list of functions that mark the last data access timestamp for update.