#include <stdio.h>
ssize_t getline(char **restrict lineptr, size_t *restrict n,
FILE *restrict stream);
ssize_t getdelim(char **restrict lineptr, size_t *restrict n,
int delim, FILE *restrict 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
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.
Both functions return -1 on failure to read a line (including end-of-file condition). In the event of a failure, errno is set to indicate the error.
| Interface | Attribute | Value |
| getline(), getdelim() | Thread safety | MT-Safe |
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 %zd:\n", nread);
fwrite(line, nread, 1, stdout);
}
free(line);
fclose(stream);
exit(EXIT_SUCCESS);
}