| NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | CONFORMING TO | EXAMPLE | SEE ALSO | COLOPHON | The Linux Programming Interface |
GETLINE(3) Linux Programmer's Manual GETLINE(3)
getline, getdelim - delimited string input
#include <stdio.h>
ssize_t getline(char **lineptr, size_t *n, FILE *stream);
ssize_t getdelim(char **lineptr, size_t *n, int delim, FILE *stream);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
getline(), getdelim():
Since glibc 2.10:
_POSIX_C_SOURCE >= 200809L || _XOPEN_SOURCE >= 700
Before glibc 2.10:
_GNU_SOURCE
getline() reads an entire line from stream, storing the address of the buffer
containing the text into *lineptr. The buffer is null-terminated and includes
the newline character, if one was found.
If *lineptr is NULL, then getline() will allocate a buffer for storing the
line, which should be freed by the user program. (In this case, the value in
*n is ignored.)
Alternatively, before calling getline(), *lineptr can contain a pointer to a
malloc(3)-allocated buffer *n bytes in size. If the buffer is not large
enough to hold the line, getline() resizes it with realloc(3), updating
*lineptr and *n as necessary.
In either case, on a successful call, *lineptr and *n will be updated to
reflect the buffer address and allocated size respectively.
getdelim() works like getline(), except that a line delimiter other than
newline can be specified as the delimiter argument. As with getline(), a
delimiter character is not added if one was not present in the input before
end of file was reached.
On success, getline() and getdelim() return the number of characters read,
including the delimiter character, but not including the terminating null
byte. This value can be used to handle embedded null bytes in the line read.
Both functions return -1 on failure to read a line (including end-of-file
condition).
EINVAL Bad arguments (n or lineptr is NULL, or stream is not valid).
These functions are available since libc 4.6.27.
Both getline() and getdelim() were originally GNU extensions. They were
standardized in POSIX.1-2008.
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
int
main(void)
{
FILE *fp;
char *line = NULL;
size_t len = 0;
ssize_t read;
fp = fopen("/etc/motd", "r");
if (fp == NULL)
exit(EXIT_FAILURE);
while ((read = getline(&line, &len, fp)) != -1) {
printf("Retrieved line of length %zu :\n", read);
printf("%s", line);
}
free(line);
exit(EXIT_SUCCESS);
}
read(2), fgets(3), fopen(3), fread(3), gets(3), scanf(3)
This page is part of release 3.32 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can be found
at http://www.kernel.org/doc/man-pages/.
GNU 2010-06-12 GETLINE(3)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface