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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | CONFORMING TO | EXAMPLE | SEE ALSO | COLOPHON |
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
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 set to NULL and *n is set 0 before the call, then
getline() will allocate a buffer for storing the line. This buffer
should be freed by the user program even if getline() failed.
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 ('\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.
EINVAL Bad arguments (n or lineptr is NULL, or stream is not valid).
ENOMEM Allocation or reallocation of the line buffer failed.
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├──────────────────────┼───────────────┼─────────┤
│getline(), getdelim() │ Thread safety │ MT-Safe │
└──────────────────────┴───────────────┴─────────┘
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(int argc, char *argv[])
{
FILE *stream;
char *line = NULL;
size_t len = 0;
ssize_t nread;
if (argc != 2) {
fprintf(stderr, "Usage: %s <file>\n", argv[0]);
exit(EXIT_FAILURE);
}
stream = fopen(argv[1], "r");
if (stream == NULL) {
perror("fopen");
exit(EXIT_FAILURE);
}
while ((nread = getline(&line, &len, stream)) != -1) {
printf("Retrieved line of length %zu:\n", nread);
fwrite(line, nread, 1, stdout);
}
free(line);
fclose(stream);
exit(EXIT_SUCCESS);
}
read(2), fgets(3), fopen(3), fread(3), scanf(3)
This page is part of release 4.12 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
GNU 2017-03-13 GETLINE(3)
Pages that refer to this page: fgetc(3), gets(3), rpmatch(3)