GETLINE(3) Linux Programmer's Manual GETLINE(3)NAME
getline, getdelim - delimited string input
SYNOPSIS
#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
DESCRIPTIONgetline() reads an entire line from stream, storing the address of the
buffer containing the text into *lineptr. The buffer is null-termi‐
nated 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 get‐
line(), a delimiter character is not added if one was not present in
the input before end of file was reached.
RETURN VALUE
On success, getline() and getdelim() return the number of characters
read, including the delimiter character, but not including the termi‐
nating null byte ('\0'). 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). In the event of an error, errno is set to indicate
the cause.
ERRORS
EINVAL Bad arguments (n or lineptr is NULL, or stream is not valid).
VERSIONS
These functions are available since libc 4.6.27.
CONFORMING TO
Both getline() and getdelim() were originally GNU extensions. They
were standardized in POSIX.1-2008.
EXAMPLE
#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);
}
SEE ALSOread(2), fgets(3), fopen(3), fread(3), gets(3), scanf(3)COLOPHON
This page is part of release 3.54 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 2013-04-19 GETLINE(3)
